doc-to-help standard template1 introduction to the model 258 about this manual this manual...

Model 258

User Manual Part No. ED48618 - Revision A

User Manual

Copyright © 2006

IRD Balancing, LLC Headquarters for IRD Balancing USA: 4740 Allmond Avenue, Louisville, KY, 40209,Tel:1(502)366-0916, Fax: 1(502)238-1001 Sales and Suport for IRD Balancing USA: 651-A Lakeview Plaza Blvd.,Worthington, OH 43085, Tel:1(614)431-5256, Fax:1(614)238-1001 For technical support, contact:[email protected]: Unit 4J, Brymau Three Estates, River Lane, Saltney, Chester, CH4 8RQ, England, Tel: +44 (0) 1244-682222, Fax: +44 (0) 1244-677977 Mexico: Miguel G. Kramer #29, Col. Atlantida, Mexico, D.F., MX 04370, Tel: +52-55-5689-8325, Fax: +52-55-5689-8160 Visit us at our website www.irdbalancing.com

mailto:[email protected]

IRD Balancing Limited Warranty LIMITED WARRANTY This product is guaranteed for 12 months from the date of shipment against defects in material and workmanship. IRD Balancing LLC will at its option, either replace or repair defective products during this warranty period. The product must be returned to IRD Balancing service centre for warranty repair or service. The customer shall pay shipping charges to IRD Balancing, return shipping charges shall be covered by IRD Balancing. The above mentioned warranty does not apply to defects due to customer misuse, operation outside of the environmental specification, unauthorised modification or repair, customer interfacing wotwith published specifications, improper or inadequate maintenance. This warranty is exclusive and no other warranty is expressed or implied. IRD

Balancing shall not be responsible for any consequential loss. SERVICE Any non authorised repair will invalidate this warranty. If service is required the product should be returned using the return procedure below. A repair quotation will be provided before any repair or servicing is carried out, free of charge. Contact our customer service department before returning the unit as the problem may be corrected on site or over the telephone. RETURN PROCEDURE To return a product to IRD Balancing please contact our customer service department, they will issue a RMA (return material authorisation) number to you, and fax a fault report form for you to fill in. To ensure efficient service, please ensure this form is filled in completely and returned with the product to our service department.

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Table of Contents

Introduction to the Model 258 1-1 About This Manual............................................ 1-1 The Model 258 Handheld ................................ 1-2 How to Set System “Control Panel” Settings 1-16

Machinery Balancing Module 2-1 Model 258 Balancing Overview ..................... 2-1 Single-Plane Balancing Overview.................. 2-1 How to Set Up the Model 258 for a Single-Plane Procedure ........................................................... 2-3 How to Perform a Single-Plane Procedure .. 2-8 Two-Plane Balancing Procedure Overview.. 2-21 How to Set Up a Two-Plane Procedure ........ 2-23 How to Perform a Two-Plane Procedure..... 2-25 Static-Couple Balancing Procedure Overview 2-38 How to Set Up a Static-Couple Procedure .. 2-39 How to Perform a Static-Couple Procedure 2-39

Analyzer Module 3-1 Overview ............................................................ 3-1 How to Set Up and Perform an Analyzer Measurement..................................................... 3-1 Saving Analyzer Spectra................................. 3-6

Bump Test Module 4-1 Overview ............................................................ 4-1 How to Set Up and Perform a Bump Test .. 4-1 Saving Bump Test Data .................................. 4-5

Glossary of Terms Glossary

Model 258 TOC - 1 User Manual

1 Introduction to the Model 258

About This Manual

This manual introduces you to IRD’s modular Model 258. It offers complete and detailed reference to both the Model 258’s hardware and its conformance check / vibration analyzer modules, including each module’s setup screens, data collection displays, and data review options.

The Model 258’s modular system consists of a base model Model 258 Windows CE® handheld device, and a range of available application modules for specific analysis needs. Available modules include:

• Analyzer Module – quickly set up a spectral measurement and immediately collect the measurement’s data for in-the-field FFT spectrum and phase analysis purposes.

• Bump Test Module – determine the natural frequencies of a machine or a structure.

• Balancing Module – resolve single-plane, two-plane, static-couple, and dynamic couple machinery balances with high precision.

• Config Module - provides options that determine various Microlog measurement setting defaults and system preferences.

In this manual, the Model 258 handheld device and each application module are described in individual chapters.

User Manual Conventions

As you use this manual, you'll discover certain conventions used:

Bold type is used to indicate text that appears in a Model 258 menu or data screen.

Italics are used to emphasize important information.

- are used to indicate notes to the reader.

Step-by-step procedures are sequenced using bullets, •.

Chapter Overview

Chapter 1, Introduction – Describes this User Manual, and describes the Model 258 handheld device. Important hardware information is detailed including battery operations, how to get around using the buttons and menus, and how to utilize the Model 258s’ connectors. Also describes Config mode options that

Model 258 1 - 1 User Manual

Introduction to the Model 258

determine various Model 258 measurement setting defaults and system preferences.

Chapter 2, Balancing Module – Describes how to set up and perform machinery balancing procedures using the Model 258.

Chapter 3, Analyzer Module - Describes how to set up and perform FFT analysis and phase measurements on the Model 258.

Chapter 4, Bump Test Module – Describes how to set up and perform bump tests (also known as hammer tests) using the Model 258.

The Model 258 Handheld

The Model 258 is a rugged, lightweight, handheld machinery vibration measurement device. Capable of use in a harsh industrial environment, it records machinery vibration measurements and processes measurement results in a variety of useful ways, depending upon installed application modules.

Figure 1 - 1. The Model 258 Displaying the Home Screen.

LED Indicators

During data collection, the three LED indicators, located above the display to the right, show the measurement’s status as data collection occurs. Data collection LED display is described below:

1 - 2 Model 258 User Manual

Introduction to the Model 258 The Model 258 Handheld

Amber only – Data collection is occurring.

Green only – Data collection is complete.

Red and green / Red and Amber – Error / ICP Error.

The Model 258 Home Screen

The Model 258 has a high resolution, supertwist, color graphic liquid crystal display (LCD).

When you first turn on the Model 258, the IRDtitle screen initially displays, showing your device’s firmware version number. After a few seconds, the Model 258 automatically displays its Home screen showing the available operating modes.

battery status /current time

application modules

Figure 1 - 2. The Model 258 Home Screen.

Available operating modes are selected with icons on the Home screen’s display area.

Model 258 1- 3 User Manual


Help Mode

On the Home screen, select the Help icon (?) to access the Model 258’s help feature, or, from other screens, press the Help function button to access the Model 258’s context sensitive help. The help screen displays and the help topic associated with your current Model 258 activity highlights.

• Use arrow keys to highlight the help topic for which you require help, and press the Goto function button to access the highlighted help topic, or use the arrow keys to access help on other topics.

The About Dialog

• From the Help screen, highlight the About help topic and press Goto to view the About dialog.

The About dialog lists all installed modules and displays your Model 258’s Firmware Version number and Unit ID number. Identify these numbers if you call customer support. The internal and PC card (if applicable) memory status levels are available by scrolling down.

If you call customer support, you will also be asked for your Model 258’s serial number located on the back of the instrument.

Model 258 Buttons and Keypad

Function Buttons

On most displays, the bottom of the screen displays command words that describe the current functions of the Model 258’s four function buttons. Each command word describes the current use of the function button beneath it. The functions of these buttons change as you operate in various Model 258 modes and displays.

How to Use the Buttons and Keypad

The graphic below locates and identifies important Model 258 buttons and keys.



2 Enter (Fire) buttons

4 function buttons

alpha / numeric keypad

arrow buttons

power button

shift button

PC card slot

Figure 1 - 3. Model 258 Buttons and Keys.

Enter (Fire) Buttons

The two Enter buttons, also known as Fire buttons, are located on either side of the LCD display. In any screen, press one of the Enter/Fire buttons to select the highlighted option, or to progress through data collection screens.

Function Buttons

The bottom of the Home screen displays up to four command words that describe the current functions of the Model 258’s four function buttons. Each command word on the display represents the function of the button beneath it. The functions of these buttons change as you operate in various Model 258 modes and displays, to allow quick access to often used features.

In all non-setup displays, the 0 / up arrow (shift) button provides alternate functions for the four function buttons.

• Press and hold the 0 / up arrow button, alternate functions display.

Arrow Buttons

The four buttons in the center of the Model 258 are identified as the up, down, left, and right arrow buttons. Use of these buttons depends on your activity:

Home Screen – On the Home screen, use all four arrow buttons to highlight the desired Model 258 operating mode, then press an Enter button to initiate the mode.



battery status

current time

Figure 1 - 4. The Home Screen.

Setup Screens – In a setup screen, use the up/down arrow buttons to highlight the field whose setting you wish to change. With the desired field highlighted, use the right/left arrow buttons to open/close the field, displaying its available settings. Then use the up/down arrow buttons to highlight the field’s new setting and press Enter.

In setup screens, when not in an input field, the 0 / up arrow (shift) button jumps the highlight to the screen’s first setting.



message area

prompt area

Figure 1 - 5. The Analyzer Module’s Setup Screen.

Beneath setup fields, setup and data display screens provide a message area and a prompt area that display messages/prompts relative to the current activity.

Data Display Screens – In a Conformance check data display screen, use the left/right arrow buttons to toggle between measurement conformance grades and measurement values. Use the up/down arrow buttons to locate a specific measurement.

Figure 1 - 6. Example of a Conformance Survey Screen Showing Measurement Grades.



Figure 1 - 7. Same Survey Showing Measurement Values.

The Alpha/Numeric Keypad

Use the alpha/numeric keypad to input both numbers and letters on the Model 258.

• To input numbers, simply press the specific number key(s), and/or the decimal key.

Numeric keys 2-9 also represent three or four alphabetical letters.

• To input letters, repeatedly press the number key representing the specific letter 2, 3, or 4 times. For example, for B, press the 2 key three times. This works in a similar manner to a cellular phone’s text entry capability.

0 / Up Arrow (Shift Key)

On the numeric keypad, the 0 / up arrow button also acts as a “shift” button that has multiple uses depending on the current Model 258 operation:

• In a setup screen numeric input field, this button acts as a zero (0) button.

• In setup screens, when not in an input field, this button jumps the highlight to the screen’s first setting.

• In all other displays, this button provides alternate functions for the four function buttons. In this use, press and hold the Shift button, alternate functions display.

Printing Model 258 Screens Using the Keypad

The Model 258 enables you to print the current display screen using its RS232 connector, its IrDA port (for printers with IrDA support), or to save display screens as graphic files to its internal disk for printing or use on a host computer.



To print using the RS232 or IrDA:

• Press the and hold the shift key (zero / up arrow) then press the P alphanumeric key. The Print Setup dialog displays. Options include:

Printer – Specify either a PCL or PocketJet 200 printer.

Baud Rate – Specify the baud rate for RS232 connection, or IrDA if applicable.

Size – Specify the size of the screen print-out. Medium is approximately one-to-one with the MX screen size.

• After setting up print options, press the OK function button to print the current display.

To save screens to the Model 258’s internal disk:

• Press the shift key (zero / up arrow) then the P alphanumeric key. The Print Setup dialog displays.

• Set the Printer option to BMP, disregard the Baud rate and Size settings, and press the OK function button. A bitmap (.bmp) file is saved to the unit’s internal disk folder, and a confirmation dialog displays. Note the filename assigned to the bitmap for further use.

Battery Operations

Power Adapter/Battery Charger

The Model 258's Power Adapter/Battery Charger (PSU-8) converts AC power to DC power required by the Model 258. The Power Adapter/Battery Charger kit includes a USB/Power Splitter Cable (CA-38) that provides connections between the Model 258, the Power Adapter/Battery Charger, and an external device’s USB communications port.

You can connect the Power Adapter/Battery Charger with your Model 258 turned on or off. The Power Adapter/Battery Charger works with AC power sources worldwide. However, verify that you have a power cable designed for use in your country.

If you are running your instrument on AC power with a battery installed, the AC Power Adapter/Battery Charger charges the battery (if needed), then maintains the battery's charge.

WARNING: The Power Adapter/Battery Charger should be placed in a ventilated area (i.e., on a desktop) when used to power the Model 258 or charge the battery. Do not use the Power Adapter/Battery Charger in a poorly ventilated area, as overheating may occur.

Install and Charge the Model 258 Battery

Prior to using the Model 258 for the first time, place the Lithium-Ion battery pack (BP-8) in the device and charge the battery for a



minimum of six hours. The Model 258's battery charges when the instrument is connected to its AC power adapter/battery charger.

You can operate the Model 258 from the external power adapter/battery charger while waiting for the battery to charge.

Once the battery is fully charged (or the Model 258 is connected to the Power Adapter/Battery Charger), it is ready for operation.

Battery Life

Primary power for the Model 258 is provided by battery packs. The battery packs operate for 6-8 hours in typical operating environments, although the actual per-charge life can vary depending on conditions, equipment options, and usage patterns.

The battery status displays in icon form in the top right corner of the title bar.

IMPORTANT: Connect the Model 258 to its Power Supply/Battery Charger whenever you do not intend to resume operations in the immediate future.

How to Install the Battery Pack

WARNING: To ensure proper operation, ONLY use the supplied battery pack.

To install the Lithium-Ion battery pack in your Model 258:

• Rotate the two screws ninety degrees on the battery cover located on the underside of your device and lift the battery cover away from the device.

• The main battery is removed by sliding the cell to the left and lifting it out of the device.

• Insert the replacement lithium-ion battery in the battery compartment and slide to the right to fit into place.

• Replace the battery cover and press down firmly on the cover while re-securing the latches.

WARNING:

Do not expose the battery pack to temperatures in excess of 140°F (60°C). Do not disassemble, incinerate, or short-circuit the battery pack.

Danger of explosion if battery is incorrectly replaced.

Replace the battery only with the same or equivalent type recommended by the manufacturer. Dispose of used batteries according to the manufacturer’s instructions.

Do not open battery compartment in a hazardous area.



Replacing the Battery in an Active Model 258

If the instrument is running from battery power only, removing the battery causes the Model 258 to shut off power to the LCD display and to PC cards. The Model 258 may lose any data stored in RAM.

To avoid these problems, use the following procedure to replace the battery pack in an active Model 258 running on battery power:

• Press the Power button to suspend the Model 258.

• Unlatch the battery and remove the pack.

• Replace with a fully charged battery pack and re-latch.

• Press the Power button.

How to Charge the Battery Pack

The Model 258's Lithium-Ion battery packs (BP-8) charge fully in 3-5 hours in the instrument. To prevent overcharging, an internal monitoring circuit shuts power off to the battery once it reaches full capacity.

IMPORTANT - Charge the battery fully before using the Model 258. Do not use the instrument during this initial charge period.

The battery is charged using the power supply. After the initial charge, you may use the Model 258 during subsequent chargings.

To charge a battery pack in the Model 258:

• Ensure the power source is plugged into a wall outlet.

• Insert the power source into the POWER connector at the top of the Model 258.

Model 258 System Connections

IrDA port

power / USB / trigger connector

RS232 port

channel 1 / 2connectors

Figure 1 - 8. Connectors on Top of the Model 258.

CH1, CH2, and Power/Trigger/USB Connectors

Sensor input signals are connected through CHannel 1 and CHannel 2 Fischer connectors at the top of the Model 258. It can accept signals from a variety of sensors; including accelerometers, velocity and displacement sensors, process inputs, etc.

Trigger input signals may also be input through CH1 and CH2, or from the Power/Trigger/USB connector when external power is not



being supplied to the unit. The standard trigger cable supplied (part no. CA-32) is for the Power/Trigger/USB connector.

CH1 provides input capabilities for X, Y, and Z signal input channels, and for a trigger input.

Not all application modules support the Y and Z inputs, or the trigger input.

CH2 provides input capabilities for Y signal input channel, and for a trigger input.

Not all application modules support the Y input or the trigger input.

Power/Trigger/USB Connector

To charge your Model 258’s batteries, connect the Power Adapter/Battery Charger to the unit’s Power connector. When power is being supplied to the unit, this connector is available for USB communications with the host computer using the supplied the splitter cable.

The maximum measurement range is +/- 40 V, while the minimum full-scale range voltage available is 10 mV (peak). Inputs are protected against higher voltage transients, however, sustained over-voltage input levels must be avoided.

The Control Panel module’s ICP setting determines whether ICP power is supplied to the transducer. Reference the How to Set System Control Panel Settings section at the end of this chapter for details.

The ICP supply is 24 Vdc (open circuit), 2.4 mA constant current.



Mating Connector Details

• CH 1/CH2: Fischer: Part No. SE103A056-130

• Power/Trigger/USB: Fischer: Part No. SE103A057-130

Pin-out CH1

Pin-out CH2

Pin-out POWER

Pin-out RS232

1 CHANNEL X 1 CHANNEL Y 1 EXT-DC-IN 1 Not Connected

2 CHANNEL Y 2 Not Connected

2 USB Client + 2 TXD-OUT

3 FIRE 3 Digital Gnd 3 USB Client- 3 RXD-IN

4 EXT-TRIG-IN

4 EXT-TRIG-IN

4 Digital Gnd 4 DTR-OUT

5 Analog Gnd 5 Analog Gnd 5 EXT-TRIG-IN 5 Digital Gnd

6 CHANNEL Z 6 +5V-Tacho Out

6 USB Client 6 Not Connected

7 +5V-TACHO-OUT

7 CTS-IN

8 RTS-OUT

9 +5v (On or Off (OC))

Microsoft® ActiveSync Communications

New modules and operating system upgrades may be installed on the Model 258 using Microsoft ActiveSync synchronization software and the USB or IrDA connectors, or by using a PC card. In addition, the Conformance Check module’s test templates are copied to the Model 258 using ActiveSync, and Conformance Check surveys along with Analyzer, Bump Test, and Recorder analysis data stored on the Model 258 may be copied (backed up) to a host computer using ActiveSync.

To download a free version of Microsoft ActiveSync, and for details on how to use ActiveSync, contact the Microsoft Corporation via their website at www.microsoft.com. Run the ActiveSync installation program and follow the on-screen instructions.

Serial Communications

To connect your Model 258 to the host computer or printer using the RS232 serial connector:

• Using a serial communications cable, connect the Model 258’s 9 PIN RS232 port to your external device’s RS232 serial port.

• Proceed with data transfer operations using ActiveSync / Windows Explorer operations.

The Model 258’s serial baud rate is fixed at 115 k.


http://www.microsoft.com/


PC Memory Card Operation

IMPORTANT – The PC / CF / SD card should not be disconnected in hazardous areas, it must be connected / disconnected in safe areas only. For hazardous areas, you must use a card manufactured by Simple Technology, model numbers STI-ATAFL/8A to STI-ATAFL/512.

The Model 258 is configured to accept any standard PCMCIA compact flash (via adapter) or digital memory card that is supported with a Microsoft Windows® CE driver. PC cards may be inserted when the instrument is powered on or off. If any memory card is not formatted to the correct standard, the instrument automatically opens a dialog prompting you to format the card. In this dialog, press either of the Enter buttons (on either side of the LCD display) to format the card for use with the Model 258.

How to Perform a Hard Reset

To hard reset your Model 258:

• With the Model 258 OFF, unscrew the battery cover on the back of the unit.

• Using a 1/16th inch pin or a straightened paper clip, press the reset button located in the lower left corner of the battery compartment, below the battery.

• The LCD screen loads the IRD Balancing title screen, then the Home screen.

How to Perform a Soft Reset

To soft reset your Model 258:

• With the instrument on, simultaneously hold down the 2, 7, 8, and 9 keys

The LCD screen will load the IRD Balancing title screen, then the Home screen. mal.



Model 258 Specifications

Environmental

CSA and FM: Class I, Division 2, Groups A, B, C, D CE Rated IP Rating: IP 65

Temperature Range Storage: -20°C to +60°C (-4°F to +140°F) Temperature Range Operating: -10°C to +50°C (+14°F to +122°F) Humidity: 95% non-condensing

Communications

Communication: 115,200 baud rates for RS-232 data transfer USB Port, Infrared Port

Printing

Pentax PocketJet or PCL compatible printers through interface. Screens can be saved to PC Card or internal memory as a windows bitmap.



How to Set System “Control Panel” Settings

Overview

This section describes Control Panel mode options that determine various Model 258 measurement setting defaults and system preferences.

To access the Control Panel screen:

• From the Home screen, use the left, right, up, and/or down arrows to select the Control Panel option.

• Press an Enter button. The Control Panel screen displays.

Figure 1 - 9. Control Panel Settings.

The Control Panel Screen

Function Buttons

OK - Press the OK function button to save all changes to Control Panel screen fields and return to the Home screen.

Cancel – Cancels any changes to setup fields and returns you the Home screen.

The following system preferences are configured from the Control Panel screen:

Press an Enter or left arrow button to accept the highlighted selection in all drop-down lists.

Date Format –Both European date (Day/Month/Year) and American date (Month/Day/Year) conventions are available. Select the appropriate format: DD/MM/YY; MM/DD/YY; YY/MM/DD


Introduction to the Model 258 How to Set System “Control Panel” Settings

Date/Time –Set the current date and time from the appropriate areas.

• Use the right and left arrow buttons to scroll between fields.

• Use the up and down arrow buttons or the numeric keypad to adjust the setting in each field.

• Press Enter or the left arrow to accept your Date/Time changes.

Time Zone – For use with Microsoft® Activesync operations. Select your time zone from the drop down list. When ActiveSync synchronizes data between the Model 258 and PC, it synchronizes the date / time on the Model 258 to the PC’s date / time. To prevent the date / time being set incorrectly, ensure the Model 258’s Time Zone setting match that of the PC.

Auto Power Off – (Off / On) Select to have the Model 258 shut down to conserve battery life after the 10 minute inactivity time period, or disable this feature.

Comms – (RS232, USB, IrDA) Specify which communication port to use for Model 258 communications.

RS232 – Select if printing to a serial printer.

RS232 / USB / IrDA– Select if communicating to a PC / printer with USB / IrDA port.

Select IrDA if using the docking station.

Printer – (PCL, PJ200, Bitmap) Specify the default printer type.

PCL – Specifies a PCL compatible printer (via RS232 port).

PJ200 – Specifies a Pentax Pocketjet 200 printer (via RS232 port).

Bitmap – Specifies to save the screen image as a bitmap file to the Model 258’s Mobile Device / Internal Disk folder.

Reference this chapter’s Printing Model 258 Screens Using the Keypad section for more information on printing.

Battery – (Good, OK, Critical, Charging) Displays battery status in text format. Battery status is also displayed on the screen’s title bar in icon form.

Good – Approximately 45% or more of battery life remains (i.e., approximately 4 hours of normal usage).

OK - Less than 45% of battery life remaining, charge the battery as soon as possible.

Critical – Very limited battery life remaining (less than 30 minutes). Charge the battery immediately, it is not recommended to continue work when the battery status is Critical.

Charging – The battery is connected to the AC Power supply and recharging.



These times apply to BP-8 battery packs. Other battery packs may give different results.

Contrast – (Increase / Decrease) Set the display contrast. Select to increase or decrease display contrast one increment. Repeat as necessary.

Tip - On most screens, press the Shift button (0, up arrow button) to utilize ”contrast” function buttons, Contr – and Contr +.

Sensor – Specify the default sensor type for Model 258 measurements.

Sensitivity – Use numeric keypad to enter the default sensor’s sensitivity in mV / EU. To correct typos, press the left arrow button to exit the field, then the right arrow to reenter the correct sensitivity.

ICP – (Automatic, On, Off) Specify default transducer coupling and power options.

Automatic – Applies settings as specified in and copied from the Conformance Check Setup Generator software.

On – Enables ICP, overiding other settings.

Off – Disables ICP, enables AC coupling, overides other settings.

If ICP power is supplied, but no transducer is connected, or there is a break in the transducer cable, an error indication is given.

Currently, the Balancing module does not use the Control Panel’s ICP setting. Balancing measurements are set up from the Balancing Setup / Options screen.

Language – Use the drop down list to select the language for Model 258 displays. After entering your selection, press OK to return to the Home screen, all display text appears in the specified language.

After specifying changes to Control Panel screen settings, press the OK function button to store your new settings in the Mod el 258. The Home screen re-display.


2 Machinery Balancing Module

Model 258 Balancing Overview

The easy to use Balancing application resolves single-plane, two-plane, and static-couple balances with high precision. Clear, comprehensive setup menus and easy-to-follow display screens with graphical data representations ensure easy operation.

The Model 258 is designed to interface with off-the-shelf laser tachometers, optical tachometers, or stroboscopes for balancing phase measurements.

For focus and ease of use, this chapter overviews and details Model 258 procedures for single-plane, two-plane, and static-couple balancing in separate sections.

Measurement Trigger Requirements

Machine balancing requires a shaft 1X signal either to the external trigger BNC input or to the phase adapter connector. The trigger signal is normally obtained from the ± TTL output of one these triggers:

• Buffered Outputs

• Laser tachometer

However, if a TTL trigger is not available, the Model 258 allows for an external analog trigger, with an appropriate trigger threshold.

Single-Plane Balancing Overview

Regardless of whether you are performing a single or two-plane balancing procedure, all balancing procedures progress through basic “runs” as you start (spin) and stop the rotor.

For two-plane procedures, you perform some of the runs twice, once with weights on correction plane one and again with weights on correction plane two. For simplicity, the following example describes a single-plane procedure.

1 - Set Up Balancing Equipment and Measurement Parameters

Stop - First, with the machine stopped, set up the balancing equipment and mark your tachometer reference point on the rotor or shaft. Use Setup menu options to configure balancing measurement parameters for the balancing run sequence.


Machinery Balancing Module

2 - Perform the Reference Run

Spin - Start the machine and perform a reference run. The reference run simply provides a “starting place” for balancing computations. It records the machine's initial imbalance (1X vibration magnitude and phase angle). Later in the procedure, reference run data is automatically compared with trial (weight) run data to calibrate the machine's imbalance.

3 - Attach a Trial Weight

Stop - After collecting reference run data, stop the machine and add a trial weight. A trial weight is a temporary weight attached to produce a change from the original unbalance readings (reference run readings). Input the trial weight amount and placement angle into the Model 258.

4 - Perform the Trial Run

Spin - With the trial weight securely attached, start the machine again, and perform a trial run with the trial weight. The trial run calibrates the machine's unbalance and allows the instrument to calculate the influence coefficient and permanent correction weight amount and placement.

To allow for accurate balancing computations, the trail weight should pass the 30/30 rule. The trial weight should:

• A - Increase or decrease the 1X vibration amplitude by at least 30%, or

• B - Change the phase angle by at least 30 degrees, or

• C - A combination of A and B.

5 - Attach the Permanent Correction Weight

Stop - Stop the machine, remove the trial weight, then attach the specified correction weight at the specified angle.

6 - Perform a Correction Weight Run

Spin - Start the machine again, and perform a correction weight run. The correction weight run performs two functions:

• It calculates the amount of residual imbalance with the correction weight in place to confirm that the machine is now balanced within tolerances.

• If further balancing is necessary, it automatically applies the influence coefficient to calculate additional “trim” weights that can be added to further balance the machine.

7 - If Necessary, Attach a Trim Weight

Stop - If additional trim weights are necessary to balance the machine within tolerances, stop the machine and attach the specified trim weights.


Machinery Balancing Module How to Set Up the Model 258 for a Single-Plane Procedure

8 - Perform a Trim Run

Spin - Start the machine and perform a trim run to verify the machine is balanced within tolerances. If not, additional trim runs may be performed.

How to Set Up the Model 258 for a Single-Plane Procedure

All balancing measurement parameters are set up from Balance Setup screens, which display immediately upon entering the balancing application.

To initiate the Balancing application:

• From the Home screen, use arrow keys to highlight the Balancing icon, and press an Enter button. The Balance Setup screen displays.

If you have performed a previous balancing job, you are automatically prompted whether you wish to re-load it. Answer No, and the Balance Setup screen displays. Answer Yes, and the previous job’s runs list on the Go to screen, allowing you to resume the previous job from any point in the procedure. Reference the Go to section later in this appendix for more information.

To exit the Balancing application:

• Press the Esc button from a balancing screen. The prompt below appears.

Figure 2 - 1. The “Quit Balancing?” Prompt.

Yes – Immediately exits the Balancing application, returning you to the Home screen.

No – Returns you to the balancing screen from which you pressed Esc.

Restart – Exits you back to the Balance Setup screen, allowing you to quickly restart your balancing procedure.

Memory – Displays the Memory – Internal screen, allowing you to save your balance job, or load other saved balance jobs.



The Balance Setup Screen

After setting up your balance measuring equipment and marking your tachometer reference point, the next step is to configure balancing measurement parameters for the balancing run sequence.

• On the Model 258, select Balancing from the Home screen. The Balance Setup screen displays.

Figure 2 - 2. The Balance Setup Screen.

Function Buttons

Function buttons at the bottom of the screen include:

Help – Press the Help function button to quickly view context sensitive on-line help.

Options – Displays the Advanced Setup screen, allowing you to enter additional setup information.

Memory – Displays the Memory – Internal screen, allowing you to save or load balancing settings and results.

Escape – Exits the balancing application, returning you to the Home screen.

Balance Setup Screen Fields

• Enter appropriate single-plane balancing setup information in the following fields:

No. of Planes – Enter 1 to specify a single-plane balancing procedure. Note that other setup fields may adjust to only display options specific to single-plane balancing.



Vib Measm’t Type – The type of vibration measurement depends on the type of sensor used (accelerometer, velocity pickup, or proximity probe) and is required to establish integration requirements for the FFT calculation. Typically, accelerometers are used to perform velocity measurements for field balancing procedures (A->V (IPS) or A->V (mm/s).

Weight Units – Select the units of measurement used for your trial, correction, and trim weights. Either g, kg, oz, lb, or EU.

Length Units – Select the units of measurement used for measuring the radius of the weight placement (from the shaft center to the position of the weight). Either mm, cm, m, inch, feet, EU. This information is used if you wish the Model 258 to estimate your trial weight for you.

Movement – Specify your weight angle placement convention, either With Rotation or Against Rotation. During a balancing procedure, when weight angle placements are specified, this setting determines their direction from the zero reference point. Against rotation is the “norm” as all other Model 258 versions use the Against Rotation convention.

Trigger Type – Select the type of phase reference trigger, either external analog or external TTL. The default setting is ext. TTL.

Trigger Slope - Select +ve (plus) or –ve (minus) to determine whether the trigger occurs on a rising or descending signal.

Trigger Level – Enter the number of volts to eliminate noise, which may cause false triggering (applicable only for external analog trigger type measurements). The default setting is two Volts.



The Advanced Setup Screen (Single-Plane Balancing)

• From the Balance Setup screen, press the Options function button. The Advanced Setup screen displays.

Figure 2 - 3. The Advanced Setup Screen.

Function Buttons


Help – Press the Help function button to quickly view context sensitive on-line help.

Apply – Applies your entered settings and returns you to the Balance Setup screen.

Escape – Exits you to the Balance Setup screen, without applying your settings.

“Advanced” Balance Setup Fields

• Enter appropriate single-plane balancing setup information in the following fields:

Filter – Select the appropriate high pass filter to filter out very low frequency noise, Off, 2 Hz, 10 Hz, 70 Hz, or User Defined. A typical setting is 2 Hz.

Detection – Determines signal detection and scaling. Acceleration, velocity, and displacement values obtained from an accelerometer or velocity pickup are always scaled from RMS detection. This replicates the measurement method used with older instruments, allowing newer Model 258 recorded values to remain equivalent.



Detection options include Peak, Pk-Pk, and RMS.

The default setting is Peak for acceleration and velocity, and Peak-to-Peak (Pk-Pk) for displacement.

Number of Averages – Specify the number of spectral averages to be included in the measurement. The default setting is 4 averages.

<Plane> – For single-plane balancing, select 1. Specifies that you are using one sensor to measure magnitude and phase for the single balancing plane, and that the settings for the following fields apply to the one sensor (Input Channel, Coupling, Sensitivity, Type, Number of Positions, and Position 1 Offset).

For two-plane balancing, you might select either 1, 2, or All, depending on your balancing equipment setup. Reference the two-plane section for specifics.

Input Channel – Select CH1 or CH2. For single-plane balancing, with the sensor connected to the Model 258’s CH1 connector.

For two-plane balancing with two sensors, you set one plane’s sensor as CH1, the other plane’s sensor as CH2 Reference the two-plane section for specifics.

Coupling – Determines the type of signal acquired for the measurement. Options are:

AC – Acquires the input signal from a buffered output (external) device.

ICP – Applies DC to the charge amplified sensor signal, and couples the dynamic signal to the input channel.

Sensitivity – Use the keypad to enter the transducer sensitivity in millivolts (mv) per Engineering Unit (EU). 100 mV/EU is used for most acceleration sensors, 200 mV/EU for most non-contact displacement sensors, and 1000 mV/EU if the input is volts and the scales is to be read directly. The default setting is 100 mV/EU.

Type – Select the appropriate weight position type,

Continuous – Specifies that weights may be placed at any placement position on the balance plane.

Fixed – (Works with Number of Positions and Position 1 Offset fields.) Specifies that weights may be placed only at designated positions (e.g., rotors having a specific weight hole pattern, or with a specific number of fan blades, etc.).

Number of Positions – (Applies to Fixed weight position measurements only.) Enter the number of weight positions, from three to 360.

The first position is assumed to be at zero degrees, subsequent positions are evenly spaced.

Position 1 Offset – (Applies to Fixed weight position measurements only.) Enter the fixed position 1 offset, from zero to 360 degrees (relative to the trigger reference).



• Press the Apply function button to save your settings and return to the Balance Setup screen.

• From the Balance Setup screen, press an Enter button to begin the single-plane balancing procedure.

How to Perform a Single-Plane Procedure

After setting up your balance measuring equipment, and setting the Model 258’s balancing measurement parameters, you are ready to perform the single-plane balancing procedure.

Perform the Reference Run

To begin the single-plane balancing procedure:

• Start the machine and bring it up to its nominal, steady running speed.

• At the Balance Setup screen, press an Enter button to begin taking reference run data. The Model 258 initiates the reference run measurements for RPM, magnitude, and phase. The Initial Run – Plane 1 screen displays the measurement results.

Figure 2 - 4. The Initial Run (Reference Run) Screen.

Important - Note the speed reading at the top of the display. For accurate balancing results, it is important to maintain the same speed across all balancing runs.


Machinery Balancing Module How to Perform a Single-Plane Procedure

Add a Trial Weight

• From the Initial Run screen, press an Enter button. The Add Trial Weight – Plane 1 screen displays.

Figure 2 - 5. The Add Trial Weight Screen.

• Stop the machine.

• On the Model 258, enter the Mass, Angle and Radius for the trial weight you are attaching to the machine.

A negative number can be entered if trial weight is removed, instead of added.

Trial weights are typically attached at zero degrees (the trigger reference).

Unless you wish the Model 258 to estimate a trial weight, the Radius entry is not necessary, so long as you position the trial, correction, and trim weights at the same radius.

• On the machine, carefully attach the precise weight at the precise angle and radius specified. Balancing results depend greatly on the precision of your measurements and actions.

If desired, the Model 258 will estimate a trial weight for you. The Summary and Estimate function buttons are discussed later in this appendix.

Perform the Trial Run

• With the trial weight securely attached to the machine, start the machine and bring it back up to the same speed used with the reference run (initial run).



• Press an Enter button. The Trial Run 1 – Plane 1 screen displays.

Figure 2 - 6. The Trial Run Screen.

The Trial Run 1 screen shows vibration magnitude and phase readings with the trial weight attached. For accurate balancing efforts, these readings should satisfy the 30/30 rule (from the reference run, the trial weight causes a 30% change in magnitude, or a 30 degree change in phase, or both).

With the 30/30 rule satisfied, the Model 258 uses differences between the reference run readings and trial run readings to compute the influence coefficient, which it uses to compute the permanent correction weight solution.

• From the Trial Run 1 screen, press an Enter button to proceed. Before computing the correction weight solution, you are prompted to indicate whether the trial weight is to remain attached or be removed.

Trial weights are normally temporary, and removed before one final correction weight is attached. However, sometimes the trial weight must be permanently attached for safety purposes, and is therefore left on the machine.



Figure 2 - 7. The “Trial Weight Left Attached?” Prompt.

• Typically, select No, as you typically plan to remove the temporary trial weight (or select Yes if you plan to leave the trial weight attached). The Correction Weight – Solution screen displays.

Add the Correction Weight

Figure 2 - 8. The Correction Weight - Solution Screen.



The Correction Weight – Solution screen displays fields at the top of the screen, and the permanent correction weight mass, angle, and radius balance solution for the field settings.

• Stop the machine, remove the temporary trial weight, and securely attach the permanent correction weight at the precise angle and radius specified.

Split Mass? - Sometimes a weight cannot conveniently be placed at the angle specified by balancing computations. The Split Mass? option automatically splits the specified weight into two weights positioned at two placement angles around the original angle.

Weight Add/Subtract – Specify whether you are adding or subtracting the correction weight. Mass and Angle settings automatically adjust per your selection. Defaults to Add.

Radius – Allows you to specify a new weight placement radius. Mass and Angle settings automatically adjust for the new radius. If you split weights, a radius setting is available for each weight.

Angle (1) / Angle (2) – Applicable only if you split weights. Allows you to specify the placement angle for the two weights. Both angles must be specified for weight recalculation. The Model 258 recalculates the weight for each position based on the relative phase between the correction weight and the split weight locations.

Perform a Correction Weight Run

• Start the machine.

• From the Correction Weight – Solution screen, press an Enter button to begin the correction run. The Correction Run screen displays, showing the amount of residual unbalance with the correction weight attached.



Figure 2 - 9. The Correction Run Screen Displaying Residual Unbalance.

• Verify whether the amount of residual unbalance is within specifications for the machine.

If the amount of residual imbalance is within specifications, you can end the balance job, if not, you should proceed with a trim run.

• From the Correction Run screen, press an Enter button to proceed. You are prompted whether you wish to perform a trim run.



Figure 2 - 10. The “Perform a Trim Run?” Prompt.

• If necessary, select Yes to proceed with a trim run. The Trim 1 Weight - Solution screen displays the trim weight data (or select No to end the balance job).

If Necessary, Attach a Trim Weight

Figure 2 - 11. The Trim 1 Weight - Solution Screen.



The Trim 1 Weight – Solution screen displays the trim weight mass, angle, and radius to help balance the residual.

• Stop the machine and securely attach the permanent trim weight at the precise angle and radius specified.

Perform a Trim Run

• With the trim weight securely attached, start the machine and press an Enter button to perform the trim run.

The Trim Run 1 screen displays the amount of residual unbalance with the trim weight attached.

• Verify whether the amount of residual unbalance is within specifications for the machine.

If the amount of residual unbalance is within specifications, you can end the balance job, if not, you should proceed with another trim run.

• Press an Enter button to proceed.

When you press No to the “Trim Residual?” prompt, the Vibration Summary screen automatically displays a summary of your job’s balancing data.

Balancing Data Summary Screens

The Summary function button is available from all balancing screens.

• Press the Summary function button to display your procedure’s Vibration Summary Table.

Figure 2 - 12. The Vibration Summary Table Screen.



The Vibration Summary Table screen displays all magnitude and phase values for each run performed during your balancing procedure.

• Press the Wts function button to display the Weights Summary Table screen.

indicatesweight has

been removed

Figure 2 - 13. The Weights Summary Table Screen.

The Weights Summary Table screen displays the mass, angle, and radius for your trial, correction, and trim weights.

If the correction or trim weights are split (in the continuous case) or fixed positions are chosen, then the two sets of correction weights display sequentially.

An asterisk next to a trial weight indicates that the weight has been removed.

How to Combine Weights

After your balancing runs, you may want to combine your correction and trim weights into a single weight.

To access the combine weights screen:

• From the Weights Summary Table, press the Comb Wt. function button. The Combine Weights screen displays.

All weights used in your balancing runs list with an adjacent check box.

To select the weights you wish to combine:

• Use the arrow keys to highlight the weights you wish to combine and press the Select function button to select (or



deselect) each weight. A check mark appears next to selected weights.

• After selecting all the weights you wish to combine into one, press the Accept button to compute your combined weight. You are prompted whether you wish to “remove all selected weights and combine with one weight?”

• Select Yes to proceed. You are prompted to enter the radius for the combined weight.

• Enter the combined weight’s placement radius and press the OK function button. The Combine Weights screen re-displays, showing the new combined weight’s mass, angle, and radius.

• Press the Esc button to return to previous screen(s). Remove the weights specified for removal, and attach the final combined weight at the precise angle and radius specified.

How to Estimate Trial Weights

At times, you may wish the Model 258 to calculate the trial weight for you.

The Trial Weight Estimate is based on the criteria that the trial run centrifugal force does not exceed 10% of the bearing shaft load.

To estimate the trial weight:

• From the Add Trial Weight screen, enter the trial weight’s Angle placement (typically zero) and Radius.

• Press the Estimate function button. You are prompted to enter the rotor’s mass support in this plane.

• Enter the rotor mass (in the Weight Units specified on the Balance Setup screen), and press the OK function button. You are returned to the Add Trial Weight screen where the estimated trial weight displays in both the Mass and Estimated Mass fields.



Figure 2 - 14. An Estimated Trial Weight.

• Reference previous sections to attach the estimated trial weight and proceed with the trial run.

How to Save your Balance Job

The Balancing application allows you to save your balance jobs for quick and easy re-balancing of the same machine at future dates. The job’s measurement settings and run data are stored with a filename for later retrieval.

You can save your balancing job at any time from the Balance Setup screen, or from the Correction and Trim Weight Solution screens. Only screens that have been accessed during the job are saved.

To save your balancing job:

• From any screen on which it is available, select the Memory function button. The Memory - Internal screen displays the names and dates of all previously saved balance jobs.



Figure 2 - 15. The Memory - Internal Screen.

• Press the Save function button. A Save As prompt displays a list that contains a <new> line item, along with all previously saved balance jobs listed by their filenames and dates.

• Highlight the <new> line to save a new job, and press the OK function button.

Alternatively, you can highlight an existing job’s filename to overwrite the existing job with the current job.

• A Save As prompt appears with a text box, allowing you to enter a filename. Type in your new job’s filename and press an Enter button. You are returned to the Memory – Internal screen, which displays the new job’s filename and date.

Loading a Saved Job, and the Go to ... Screen

You may load a previously saved balance job to resume its balancing procedure from any point, or simply to reference the job’s data.

To load a previously saved balance job:

• From the Memory – Internal screen, press the Load function button and specify the name of the job to load. The job’s screens list in the Go to ... screen.

• Alternatively, during a balancing job, hold down the (0) key, a Go to function button displays. Press the Go to function button to display the job’s Go to ... screen.



Figure 2 - 16. The Go to ... Screen.

Enabled check boxes next to screen names indicate screens that were accessed during the job. Only screens that you have already accessed are available.

• Highlight a screen with a check and press the Go to pt function button to display the screen.

• If necessary, resume the balancing procedure from this screen.

Alternatively, you may simply reference the balancing data and press the Esc function button to quit the Balancing application.


Machinery Balancing Module Two-Plane Balancing Procedure Overview

Two-Plane Balancing Procedure Overview

With two-plane balancing, the measurement sequence proceeds in the same order as with single-plane balancing, except two trial weights and two trial runs are required to calculate four influence coefficients (only one influence coefficient exists for single-plane).

sensor A sensor B

plane 1 plane 2

bearing block A

bearing block B

Figure 2 - 17. Example of a Two-plane Balancing Setup.

1 - Set Up Balancing Equipment and Measurement Parameters

Stop - First, with the machine stopped, set up the balancing equipment and mark your tachometer reference point on the rotor or shaft. Use Model 258 Setup menu options to configure balancing measurement parameters for the balancing run sequence.

2 - Perform the Reference Runs (Planes 1 and 2)

Spin - Start the machine and perform two reference runs (initial runs), one on each balancing plane. The reference runs provide a “starting place” for balancing computations. They record the machine's initial imbalance (1X vibration magnitude and phase angle) on each balancing plane. Later in the procedure, reference run data is automatically compared with trial (weight) run data to calibrate each planes unbalance.

3 - Attach Trial Weight to Plane 1

Stop - After collecting reference run data, stop the machine and add a trial weight to plane 1. A trial weight is a temporary weight attached to produce a change from the original unbalance readings (reference run readings). Input the trial weight amount and placement angle into the Model 258.

4A - Perform the Trial Run on Plane 1

Spin - With the trial weight securely attached, start the machine again, and perform a trial run on plane 1. The trial run calibrates the machine's unbalance and allows the Model 258 to calculate the



influence coefficient and permanent correction weight amount and placement.

To allow for accurate balancing computations, the trail weight should pass the 30/30 rule. The trial weight should:

• A - Increase or decrease the 1X vibration amplitude by at least 30%, or

• B - Change the phase angle by at least 30 degrees, or

• C - A combination of A and B.

4B - Perform the Trial Run on Plane 2

Spin – With the trial weight on Plane 1, perform a trial run on Plane 2.

5 – Attach the Trial Weight to Plane 2

Stop – Stop the machine, remove the trial weight from Plane 1 and attach it to Plane 2.

6A – Perform Trial Run on Plane 1

Spin - With the trial weight on Plane 2, perform a Trial Run on Plane 1.

6B – Perform Trial Run on Plane 2

Spin - With the trial weight on Plane 2, perform a Trial Run on Plane 2.

7 - Attach the Permanent Correction Weights

Stop - Stop the machine, remove the trial weight from Plane 2, then attach the specified correction weights at the specified angles on each balance plane (1 and 2).

8A - Perform a Correction Weight Run on Plane 1

Spin - Start the machine again, and perform a Correction Weight Run on Plane 1.

The correction weight run performs two functions:

• It calculates the amount of residual imbalance with the correction weights in place to confirm that the plane is now balanced within tolerances.

• If further balancing is necessary, it automatically applies the influence coefficient to calculate an additional “trim” weight that can be added to further balance the plane.

8B - Perform a Correction Weight Run on Plane 2

Spin - Perform a Correction Run on Plane 2.


Machinery Balancing Module How to Set Up a Two-Plane Procedure

9 - If Necessary, Attach the Trim Weights

Stop - If additional trim weights are necessary to balance the machine within tolerances, stop the machine, and attach the specified trim weights to their appropriate planes.

10A - Perform a Trim Run on Plane 1

Spin - Start the machine and perform a trim run on Plane 1 to verify it is balanced within tolerances. If not, additional trim runs may be performed.

10B - Perform a Trim Run on Plane 2

Spin - Perform a trim run on Plane 2 to verify it is balanced within tolerances. If not, additional trim runs may be performed.

How to Set Up a Two-Plane Procedure

Figure 2 - 18. The Balance Setup Screen with 2 Planes Selected.

Specific differences exist between single and two-plane balancing measurement field settings. Setup options specific to two-plane procedures are detailed below. Reference the How to Set Up the Model 258 for a Single-plane Procedure section for all other settings that apply to both single and two-plane balancing.



Setup Options Specific to Two-Plane Balancing

No. of Planes – Enter 2 to specify a two-plane balancing procedure. Note that other setup fields may adjust to display options specific to two-plane balancing.

Solution –Influence Coefficient or Quasi-Static. Select Influence Coefficient to compute two correction weight solutions for a two-plane balancing procedure.

A Quasi-Static option is available for situations where you wish to compute three correction weights, one to correct the static unbalance, and two to correct the couple unbalance (static-couple balancing). Reference the Static-Couple section later in this manual for details.

<Plane> – For two-plane balancing, works with the following Input Channel, Coupling, Sensitivity, Type, Number of Positions, and Position 1 Offset fields to set up each balancing plane’s sensor and weight placement settings for the following balancing setups:

• One Sensor / Two Identical Planes - When two-plane balancing with one sensor (where the balancing planes are identical) – select All. Then set the following Input Channel ( typically X), Coupling, Sensitivity, Type, Number of Positions, and Position 1 Offset fields as appropriate for the one sensor and the identical balancing planes.

• One Sensor / Two Differing Planes - When two-plane balancing with one sensor (where balancing plane weight pattern positions are different for each plane), first select 1, and set up the sensor (CH1) and balancing plane one’s weight pattern settings. Then return to the Plane field and select 2, to set up the same sensor (same sensor settings, also CH1) and balancing plane two’s differing weight pattern settings.

• Two Sensors - When two-plane balancing with two sensors (regardless of the type of sensor used for each plane, or whether the two balancing planes are identical), first select 1, and set up the first sensor (CH1) and balancing plane one’s weight pattern settings. Then return to the Plane field and select 2, to set up the second sensor (CH2) and the second balancing plane’s settings.

Each plane’s weight position radius is specified during the balancing procedure, at the Add Trial Weight screen.

Input Channel – (Reference the above <Plane> field description.) Select CH1or CH2. For two-plane balancing with one sensor, set the sensor as CH1. For two-plane balancing with two sensors, set one plane’s sensor as CH1, the other plane’s sensor as CH2.

Coupling – (Reference the above <Plane> field description.) Determines the type of signal acquired for the sensor(s). Options are:


Machinery Balancing Module How to Perform a Two-Plane Procedure

AC – Acquires the input signal from a buffered output (external) device.

ICP – Applies DC to the charge amplified sensor signal, and couples the dynamic signal to the input channel.

Sensitivity – (Reference the above <Plane> field description.) Use the keypad to enter the sensor(s) sensitivity in millivolts (mv) per Engineering Unit (EU). 100 mV/EU is used for most acceleration sensors, 200 mV/EU for most non-contact displacement sensors, and 1000 mV/EU if the input is volts and the scales is to be read directly. The default setting is 100 mV/EU.

Type – (Reference the above <Plane> field description.) Select the appropriate weight position type,

Continuous – Specifies that weights may be placed at any placement position on the balance plane.

Fixed – (Works with Number of Positions and Position 1 Offset fields.) Specifies that weights may be placed only at designated positions (e.g., rotors having a specific weight hole pattern, or with a specific number of fan blades, etc.).

Number of Positions – (Applies to Fixed weight position measurements only.) Enter the number of weight positions for the respective plane, from three to 360.

The first position is assumed to be at zero degrees, subsequent positions are evenly spaced.

Position 1 Offset – (Applies to Fixed weight position measurements only.) Enter the fixed position 1 offset for the respective plane, from zero to 360 degrees.

• Press the Apply function button to save your settings and return to the Balance Setup screen.

• From the Balance Setup screen, press an Enter button to begin the two-plane balancing procedure.

How to Perform a Two-Plane Procedure

After setting up your balance measuring equipment, and setting the Model 258’s balancing measurement parameters, you are ready to perform the two-plane balancing procedure.

Perform the Reference Runs

To begin the two-plane balancing procedure:

• Start the machine and bring it up to its steady running speed.

• At the Balance Setup screen, press an Enter button to begin taking reference run data. You are prompted to verify the sensor is attached to the bearing nearest Plane 1.



• Verify the sensor and press OK. The Model 258 initiates the reference run measurements for Plane 1. The Initial Run – Plane 1 screen displays the measurement results.

Figure 2 - 19. The Initial Run – Plane 1 Screen.

• Press an Enter key to proceed. You are prompted to verify the sensor is attached to the bearing nearest Plane 2.

• Verify the sensor and press OK. The Model 258 initiates the reference run measurements for Plane 2. The Initial Run – Plane 2 screen displays the measurement results.



Figure 2 - 20. The Initial Run – Plane 2 Screen.

Attach a Trial Weight to Plane 1

• From the Initial Run – Plane 2 screen, press an Enter button. The Add Trial Weight – Plane 1 screen displays.

Figure 2 - 21. The Add Trial Weight – Plane 1 Screen.




• On the Model 258, enter the Mass, Angle and Radius for the trial weight you are attaching to Plane 1.


Trial weights are typically attached at zero degrees.

Unless you wish the Model 258 to estimate a trial weight, the Radius entry is not necessary, so long as you position the trial, correction, and trim weights at the same radius.

• On the machine, carefully attach the precise weight at the precise angle and radius specified. Balancing results depend greatly on the precision of your measurements and actions.

Perform Trial Run 1 on both Planes

• With the trial weight securely attached to the machine, start the machine and bring it back up to the same speed used with the reference runs (initial runs).

• Press an Enter button. You are prompted to verify the sensor is attached to the bearing closest to Plane 1.

• Verify your sensor is attached and press the Yes function button. The Trial Run 1 – Plane 1 screen displays.

Figure 2 - 22. The Trial Run 1 – Plane 1 Screen.

The Trial Run 1 – Plane 1 screen shows vibration magnitude and phase readings for Plane 1 with the trial weight on Plane 1. For accurate balancing efforts, these readings should satisfy the 30/30 rule (from the reference run, the trial weight causes a 30% change in magnitude, or a 30 degree change in phase, or both).



• From the Trail Run 1 – Plane 1 screen, press an Enter button to proceed. You are prompted to verify the sensor is attached to the bearing nearest Plane 2.

• Verify the sensor and press OK. The Trial Run 1 – Plane 2 screen displays.


The Trial Run 1 – Plane 2 screen shows vibration magnitude and phase readings for Plane 2 with the trial weight on Plane 1.

• Press an Enter key to proceed. You are prompted whether the trial weight is to remain attached to Plane 1.

Trial weights are normally temporary, and removed before one final correction weight is attached. However, at times the trial weight must be permanently attached for safety purposes, and is therefore left on the machine.

• Typically, select No, as you typically plan to remove the temporary trial weight (or select Yes if you plan to leave the trial weight attached). The Add Trial Weight – Plane 2 screen displays.



Attach the Trial Weight to Plane 2

Figure 2 - 24. The Add Trial Weight – Plane 2 Screen.


• On the Model 258, enter the Mass, Angle and Radius for the trial weight you are attaching to Plane 2 (typically the same weight used on Plane 1).


Trial weights are typically attached at zero degrees.

• On Plane 2, carefully attach the precise weight at the precise angle and radius specified. Balancing results depend greatly on the precision of your measurements and actions.

Perform Trial Run 2 on both Planes

• With the trial weight securely attached to the Plane 2, start the machine and bring it back up to the same speed used with the reference runs (initial runs).

• Press an Enter button. You are prompted to verify the sensor is attached to the bearing closest to Plane 1.

• Verify your sensor is attached and press the Yes function button. The Trial Run 2 – Plane 1 screen displays.





• From the Trail Run 2 – Plane 1 screen, press an Enter button to proceed. You are prompted to verify the sensor is attached to the bearing nearest Plane 2.

• Verify the sensor and press OK. The Trial Run 2 – Plane 2 screen displays.





• Press an Enter key to proceed. Before computing the correction weight solution, you are prompted whether the trial weight is to remain attached to Plane 1.

• Typically, select No, as you typically plan to remove the temporary trial weight (or select Yes if you plan to leave the trial weight attached). The Correction Weight - Solution screen displays for Plane 1 of 2.



Add the Correction Weights

Figure 2 - 27. The Correction Weight - Solution Screens for both Planes.

The Correction Weight – Solution screen displays fields at the top of the screen, and the permanent correction weight mass, angle, and radius balance solution for the two-planes at the bottom of the screen.

• Use the Plane field to view each Plane’s correction weight data.



• Stop the machine, remove the temporary trial weight from Plane 2, and securely attach the permanent correction weights on Planes 1 and 2 (at the precise angles and radii specified).

Perform Correction Weight Runs on both Planes


• With your permanent correction weights in place on both planes, from the Correction Weight – Solution screen, press an Enter button to begin the correction runs. You are prompted to verify the sensor is attached to the bearing closest to balancing Plane 1.

• Verify the sensor and press Yes. The Correction Run – Plane 1 screen displays, showing the amount of residual unbalance on Plane 1 with the correction weights attached.

Figure 2 - 28. The Correction Run – Plane 1 Screen Displaying Residual Plane 1 Unbalance.

• Verify whether the amount of residual unbalance is within specifications.

• From the Correction Run – Plane 1 screen, press an Enter button. You are prompted to verify the sensor is attached to the bearing nearest Plane 2.

• Verify the sensor and press OK. The Correction Run – Plane 2 screen displays, , showing the amount of residual unbalance on Plane 2 with the correction weights attached.



Figure 2 - 29. The Correction Run – Plane 2 Screen Displaying Residual Plane 2 Unbalance.


• From the Correction Run – Plane 2 screen, press an Enter button. You are prompted whether you wish to trim the residual unbalance.

• If necessary, select Yes to proceed with trim runs. The Trim 1 Weight - Solution screen displays the trim weight data (or select No to end the balance job).



Attach the Trim Weights

Figure 2 - 30. The Trim 1 Weight - Solution Screen for Plane 1.

The Trim 1 Weight – Solution screen displays the trim weight mass, angle, and radius for both planes.

• Use the Plane field to view each Plane’s trim weight data. Write each field’s trim weight data on a piece of paper before proceeding.

• Stop the machine, and securely attach the trim weights on Planes 1 and 2 (at the precise angles and radii specified).

Perform Trim Runs on both Planes


• With your trim weights attached on both planes, from the Trim Weight – Solution screen, press an Enter button to begin the trim runs. You are prompted to verify the sensor is attached to the bearing closest to balancing Plane 1.

• Verify the sensor and press Yes. The Trim Run – Plane 1 screen displays, showing the amount of residual unbalance on Plane 1 with the trim weights attached.


• From the Trim Run – Plane 1 screen, press an Enter button. You are prompted to verify the sensor is attached to the bearing nearest Plane 2.



• Verify the sensor and press OK. The Trim Run 1 – Plane 2 screen displays, , showing the amount of residual unbalance on Plane 2 with the trim weights attached.


• From the Trim Run 1 – Plane 2 screen, press an Enter button. You are again prompted whether you wish to trim the residual unbalance.

If the amount of residual unbalance is within specifications, you can end the balance job, if not, you should proceed with another trim run.

When you press No to the “Trim Residual?” prompt, the Vibration Summary Table automatically displays a summary of your job’s balancing data.



Static-Couple Balancing Procedure Overview

Figure 2 - 31. A Narrow Rotor Showing Three Heavy Spots.

With stiffer rotors, a two-plane procedure may reduce the amount of imbalance to target tolerances. However, with narrow or flexible rotors, more often a static-couple (quasi-static) procedure works best.

The static-couple procedure first corrects the static unbalance with weights added to the center of gravity plane, then corrects the couple unbalance with weights added to the end planes.

In practice, a static-couple balancing procedure is almost identical to a two-plane balancing procedure, except that it provides three correction weight solutions instead of two. One correction weight for each plane, and an additional correction weight to correct the static unbalance.

Unless you are able to attach weights to the machine’s center of gravity plane, the “static” weight is typically split in half and applied to the end planes to correct the static unbalance.

In as such, on the Model 258, the static-couple procedure is identical to the two-plane procedure except Correction Weight and Trim Weight screens show three correction weights for the static-couple procedure:

• One weight for end plane 1.

• One weight for end plane 2.

• One weight for the center of gravity plane (static weight). Again, this weight may be split in half and applied to the two end planes if you are unable to attach weight to the center of gravity plane.

Except for attaching three correction and trim weights instead of two (or four if you split the static weight), all static-couple balancing run procedures are identical to the two-plane balancing procedures.


Machinery Balancing Module How to Set Up a Static-Couple Procedure

How to Set Up a Static-Couple Procedure

Except for the Solution field, all static-couple balancing settings are identical to two-plane balancing settings. Reference the previous How to Set Up a Two-Plane Procedure section for settings that apply to both two-plane and static-couple balancing.

Setup Options Specific to Static-couple Balancing

Figure 2 - 32. The Advanced Setup Screen with the Quasi-static Solution Selected.

Solution –Influence Coefficient or Quasi-Static. Select Quasi-Static to compute three correction weights for the static-couple procedure, as described above.

How to Perform a Static-Couple Procedure

Again, except for attaching three correction and trim weights instead of two (or four if you split the static weight), all static-couple balancing run procedures are identical to the two-plane balancing procedures. Reference this appendix’s How to Perform a Two-Plane Procedure section for details.


3 Analyzer Module

Overview

The Model 258’s Analyzer module allows you to quickly set up spectral / phase measurements and immediately collect the measurement’s data for in-the-field FFT spectrum and phase analysis purposes. After data collection, the measurement’s data may be stored in the Model 258 for future review, and can be transferred to the host computer in comma separated value format (.csv) for import and analysis into the Analysis and reporting module or spreadsheet applications such as Microsoft Excel.

Analyzer measurement setups can be stored in the Model 258 and quickly recalled for future use.

The Analyzer module is intended for steady state machinery analysis.

How to Set Up and Perform an Analyzer Measurement

Overview

As the Analyzer module is intended to measure machinery running in steady state conditions, some settings are pre-set to simplify user setup. Pre-set measurement parameters are:

• Autoranging - On

• Number of Averages – Five

• Average Type – Exponential

• FFT Window – Hanning

• Overlap – 50 %

• Trigger – Free Run

To set-up an Analyzer measurement:

• Attach the sensor to the test object (machine case or structure).

• From the Home screen, use arrow keys to highlight the Analyzer icon, and press an Enter button. The Analyzer menu displays.


Analyzer Module

Figure 3 - 1. The Analyzer Menu.

Analyzer menu options are:

Setup – Displays Analyzer setup fields and begins data collection.

Recall – If you have saved a previous Analyzer measurement’s settings, you may recall them to perform another measurement using the same settings.

Review Data – Initiates the Analyzer – Review Data screen allowing you to review saved measurement data.

• From the Analyzer menu, select Setup,. the Analyzer - Setup screen displays.


Analyzer Module How to Set Up and Perform an Analyzer Measurement

Figure 3 - 2. The Analyzer Setup Screen.

Function Buttons


Back – Returns you the Analyzer menu.

Save – Saves the current settings. Enter a filename to identify the measurement settings.

Start – Take Analyzer data using the current settings.

Analyzer Setup Fields

• Enter appropriate setup information in the following fields:

Sensor Type – Specifies the type of sensor used on CH1. (typically Accel G) Note that the specified sensor type determines available options and engineering units for subsequent setup fields.

For phase measurements, connect a similar sensor with the same sensitivity to the CH2 connector and set the following View Signal field to Spectrum and Phase. CH1’s sensor is the roving sensor, CH2’s sensor is the reference sensor. The roving sensor is placed around the machine to make comparative phase measurements relative to the reference sensor.

Sens. (mV/EU) – Use the alphanumeric keypad to enter transducer sensitivity in millivolts (mV) per Engineering Unit (EU).

Y-axis units – Derives the measurement type and units. Options include Accel G, Accel m/s2, Vel IPS, Vel mm/s, Disp µm, Disp mil, Disp thou, gE (enveloped acceleration), Time.


Analyzer Module

If Y-axis units is set to gE, then the following View Signal option should be set to Spectrum. If View Signal is set to Spectrum and Phase, invalid gE data occurs.

X – axis units (Default Units) – (Hz or CPM) Specify frequency units for graphic displays.

Detection – (RMS, Peak, Pk-Pk, True Pk, or True Pk-Pk). Select the method of dynamic signal detection from the list.

Filter – As determined by the Y-axis units setting. the drop-down list displays two types of filter settings, High-pass filter settings to remove low frequency interference for standard vibration measurements, and Enveloper Band pass filter settings to focus an enveloped acceleration (gE) measurement on the harmonic frequency range of interest.

Freq Range (Fmax)– Use the alphanumeric keypad to enter the FFT upper full-scale frequency, up to 40,000 Hz (2,400,000 CPM). (Typically 1000 Hz for normal machinery speeds).

Lines – Specify the spectrum’s lines of resolution. Note - increased resolution requires increased time for data collection and consumes more storage memory.

Samples – (Available only when Y-axis units is set to Time). From the drop down list, specify the number of samples to record on the time waveform. Together the number of Samples and the specified Freq Range determine the measurement’s acquisition time, which displays in the setup screen’s message area.

View Signal – Select from the drop down list whether to display the signal in Spectrum or in Spectrum and Phase format.

For phase measurements, connect a sensor similar to the one connected to CH1 to the CH2 connector.

Display Y-axis – (Linear or Logarithmic) Specify the type of y-axis scaling.

• After setting Analyzer setup fields, if desired, press the Save function button to name and save the current measurement settings for future recall.

Performing an Analyzer Measurement

• From the Setup screen, press the Start function button to begin data collection. The Analyzer – Taking Data screen displays the FFT spectrum and, if specified, the comparative phase reading.


Analyzer Module How to Set Up and Perform an Analyzer Measurement

cursor frequency / amplitude

overall reading

pause acquisition

Figure 3 - 3. Example of an Env. Acc. Measurement’s Analyzer Display.

With exponential averaging, the Model 258 continuously averages readings to minimize the noise level. Press the Pause function button to pause the acquisition process, then press Start to continue acquisition.

• Move the spectral cursor to identify spectral frequencies of interest.

Press P to jump the cursor to the next peak, or press H to display harmonic markers for the cursor position.

• For phase readings, move the cursor between peak amplitudes to observe the phase difference between the peak amplitude components of the roving sensor to the reference sensor.

Taking Phase Measurements

When using both channels to take phase measurements, channel one should be used as the phase reference (static sensor), the roaming sensor should be attached to channel two, this prevents negative results from being generated.

Phase readings do not shift by ninety degrees when integrating between acceleration, velocity, and displacement. Phase measurements are intended to be used in comparison to diagnostic charts.


Analyzer Module

cursor time / amplitude

overall reading

pause display

Example of a Time Waveform Analyzer Display.

Example of an Enveloped Acceleration (gE) Analyzer Display.

Saving Analyzer Spectra

• From the Analyzer – Taking Data screen, press the Save function button to name and save the current Analyzer measurement results for later review


Analyzer Module Saving Analyzer Spectra

Analyzer spectra are stored in comma separated value format (.csv) in the Model 258’s Mobile Device/Internal Disk/Analyzer folder. These .csv spectra files may be viewed with the Model 258’s Analyzer module, or may be copied to the host computer and viewed with Microsoft Excel or other analysis software.

Saving, Reviewing, Backing Up, and Deleting Measurements

Procedures for saving measurement setups, for saving measurement results, for backing up measurements, for viewing stored measurements, and for deleting stored measurements are similar between modules. Reference Chapter 2, Conformance Check Module sections on How to Save / Backup Measurements, How to View Stored Measurements, and How to Delete Stored Measurements for detailed information on these procedures.


4 Bump Test Module

Overview

A bump test (also called a hammer test) determines the natural frequencies of a machine or a structure. The idea behind the test is that when an object is impacted or “bumped,” the object's natural or resonant frequencies are excited. If a spectrum is taken while the object is vibrating due to the impact, spectral peaks result, pinpointing the object's natural frequencies. The Model 258 can be used to capture this vibration response and to display a spectrum showing the resonant or natural frequencies.

The bump test module is included as part of the FFT Analyzer module. However, it is displayed as a separate icon on the Home screen.

Why Do a Bump Test?

Vibration forces transmitted by rotating machines often excite natural resonance in attached structures. Whenever such structural resonances appear, vibration responses are amplified and can result in fatigue failures. Structural resonances can also mask the cause of a machine's vibration, making it difficult to implement corrective machine maintenance. Bump tests identify a structure's resonant modes and provide a maintenance engineer the opportunity to change the resonance frequency so as to reduce or eliminate damaging vibration.

How to Set Up and Perform a Bump Test

Overview

For a bump test, some vibration measurements settings are pre-set to simplify user setup. Pre-set measurement parameters are:

• FFT Window – Hanning

• Overlap – 50 %

To set-up a Bump Test measurement:

• Attach the sensor to the test object (machine case or structure).

• From the Home screen, use arrow keys to highlight the Bump Test icon, and press an Enter button. The Bump Test menu displays.


Bump Test Module

Figure 4 - 1. The Bump Test Menu.

Bump Test menu options are:

Setup – Displays bump test setup fields and begins data collection.

Recall – If you have saved a previous bump test’s settings, you may recall them to perform another bump test using the same settings.

Review Data – Initiates the Bump Test – Review Data screen allowing you to review saved bump test data.

• From the Bump Test menu, select Setup, the Bump Test - Setup screen displays.


Bump Test Module How to Set Up and Perform a Bump Test

Figure 4 - 2. The Bump Test Setup Screen.

Function Buttons


Back – Returns you the Bump Test menu.

Save – Saves the current bump test settings. Enter a filename to identify the bump test settings.

Start – Take bump test data using the current settings.

Bump Test Setup Fields

• Enter appropriate setup information in the following fields:

Sensor Type – Specifies the type of sensor used. (typically Accel G) Note that the specified sensor type determines available options and engineering units for subsequent setup fields.

Sens. (mV/EU) – Use the alphanumeric keypad to enter transducer sensitivity in millivolts (mv) per Engineering Unit (EU).

Range (EU) (Full Scale) – Enter a number to define the spectrum’s maximum amplitude value (full scale) (typically 20 G).

X – axis units (Default Units) – (Hz or CPM) Specify frequency units for graphic displays.

Filter – The drop-down list displays High-pass filter settings. (Typically 2 Hz)

Freq Range (Fmax)– Use the alphanumeric keypad to enter the FFT upper full-scale frequency, up to 40,000 Hz (2,400,000 CPM). (Typically 1000 Hz for normal machinery speeds)


Bump Test Module

Lines – Specify the spectrum’s lines of resolution. Note - increased resolution requires increased time for data collection and consumes more storage memory (typically 400 lines).

Avg. Type – (Pk Hold or Exponential) For bump tests, specify Peak Hold averaging. The Model 258 holds the highest spectral peak for each hammer hit. For exponential averaging, the Model 258 averages multiple hits to minimize the noise level, however, you must pause the averaging process after the last hit.

Display Y-axis – (Linear or Logarithmic) Specify the type of y-axis scaling. Typically set to Linear.

• After setting bump test setup fields, if desired, press the Save function button to name and save the current settings for future recall.

• Press the Start function button to begin data collection. The Bump Test – Taking Data screen displays.

Figure 4 - 3. The Bump Test Taking Data Screen.

• Commence bump test hammer hits to display natural frequency spectral peaks.

• Move the spectral cursor to identify natural frequencies.


Saving Bump Test Data

Saving Bump Test Data

• If desired, press the Save function button to name and save the current bump test display for later review.

Bump test spectra are stored in comma separated value format (.csv) in the Model 258’s Mobile Device/Internal Disk/Analyzer folder. These .csv spectra files may be viewed with the Model 258’s Bump Test or Analyzer modules, or may be copied to the host computer and viewed with Microsoft Excel or other host application.

Saving, Reviewing, Backing Up, and Deleting Measurements Procedures for saving measurement setups, for saving measurement results, for backing up measurements, for viewing stored measurements, and for deleting stored measurements are similar between modules.


Glossary of Terms Acceleration - The time rate of change of velocity. Acceleration measurements are usually made with accelerometers. Accelerometer - A sensor who’s output is directly proportional to acceleration. Alarm Setpoint - Any value beyond which is considered unacceptable or dangerous to machinery operation. Alignment - A condition whereby the axes of machine components are either coincident, parallel, or perpendicular, according to design requirements. Amplitude - The magnitude of dynamic motion or vibration. Expressed in terms of peak-to-peak, zero-to-peak, or RMS. Asynchronous - Vibration components that are not related to rotating speed. Averaging - In a dynamic signal Analyzer, digitally averaging several measurements to improve statistical accuracy or to reduce the level of random asynchronous components. Axial - In the same direction as the shaft centerline. Axial Vibration - Vibration that is in line with a shaft centerline. Axis - The reference plane used in plotting routines. The X-axis is the frequency plane. The Y-axis is the amplitude plane. Balancing - A procedure for adjusting the radial mass distribution of a rotor so that the centerline of the mass approaches the geometric centerline of the rotor. Band-Pass Filter - A filter with a single transmission band extending from lower to upper cutoff frequencies. The width of the band is determined by the separation of frequencies at which amplitude is attenuated by 3 dB (0.707). Bandwidth - The spacing between frequencies at which a band-pass filter attenuates the signal by 3 dB. Baseline Spectrum - A vibration spectrum taken when a machine is in good operating condition; used as a reference for monitoring and analysis. Baud Rate - Adjustable serial communication transfer rate. Measured in bits per second. Bit - Smallest unit of computer information storage. Equivalent to a choice of a one or a zero. Byte - A unit of computer information storage usually equal to eight bits or one character. Center Frequency - For a bandpass filter, the center of the transmission band. Centerline Position - The average location, relative to the radial bearing centerline, of the shaft dynamic motion. Channel - A sensor and the instrumentation hardware and related software required to display its output signal. Condition Monitoring - Determining the condition of a machine by interpretation of measurements taken either periodically or continuously while the machine is running. CPM - Cycles per minute. CPS - Cycles per second. Also referred to as Hertz (Hz).

Glossary Model 258 User Manual

Critical Speeds - In general, any rotating speed that is associated with high vibration amplitude. Often the rotor speeds that correspond to natural frequencies of the system. Cycle - One complete sequence of values of a periodic quantity. Displacement - The change in distance or position of an object relative to a reference. Download - Transferring information to the measurement device from the host computer. Enable - To activate. Engineering Units - Physical units in which a measurement is expressed, such as in/sec, micrometers, or mils. Selected by the user. EU - See ENGINEERING UNITS. External Sampling - In a DSA refers to control of data sampling by a multiplied tachometer signal. Provides a stationary display of vibration with changing speed. Fast Fourier Transform - A calculation method of converting a time waveform to a frequency display that shows the relationship of discrete frequencies and their amplitudes. Field - One data item. Examples of fields are POINT Type, Description, etc. Filter - An electronic device designed to pass or reject a specific frequency band. FFT - See Fast Fourier Transform. Flat Top Window - DSA window function that provides the best amplitude accuracy for measuring discrete frequency components. Frequency - The repetition rate of a periodic event, usually expressed in cycles per second (Hz), cycles per minute (CPM), revolutions per minute (RPM), or multiples of running speed (orders). Orders are commonly referred to as 1X for running speed, 2X for twice running speed, and so on. Frequency Domain - An FFT graph (amplitude vs. frequency). Free Running - A term used to describe the operation of an Analyzer or processor that operates continuously at a fixed rate, not in synchronism with some external reference event. Frequency Range - The frequency range (bandwidth) over which a measurement is considered valid. Usually refers to upper frequency limit of analysis, considering zero as the lower analysis limit. Gap - (See Probe Gap.) Global Bearing Defect - Relatively large damage on a bearing element. Hanning Window - DSA window function that provides better frequency resolution than the flat top window, but with reduced amplitude accuracy. Hertz (Hz) - Cycles per second. CPM/60. Hierarchy - A method of organizing equipment into logical groups or physical areas for ease of access in the PRISM4 database. This format consists of Main SETs, Sub-SETs, machines, and measurement POINTs. High Pass Filter - A filter with a transmission band starting at a lower cutoff frequency and extending to (theoretically) infinite frequency. Imbalance - A condition such that the mass of a shaft and its geometric centerlines do not coincide. Keyphasor Phase Reference Sensor - A signal used in rotating machinery measurements, generated by a sensor observing a once-per-revolution event. (Keyphasor is a Bently-Nevada trade name.) Linear Averaging - In a DSA, averaging of time records that results in reduction of asynchronous components.

Model 258 Glossary User Manual

Lines - Common term used to describe the filters of a DSA (e.g., 400 line Analyzer). Low Pass Filter - A filter whose transmission band extends from an upper cutoff frequency down to DC. Multi-Parameter Monitoring - A condition monitoring method that uses various monitoring technologies to best monitor machine condition. Natural Frequency - The frequency of free vibration of a system. The frequency at which an undamped system with a single degree of freedom will oscillate upon momentary displacement from its rest position. Orbit - The path of shaft centerline motion during rotation. Overlap Processing - The concept of performing a new analysis on a segment of data in which only a portion of the signal has been updated (some old data, some new data). Peak Spectra - A frequency domain measurement where, in a series of spectral measurements, the one spectrum with the highest magnitude at a specified frequency is retained. Phase - A measurement of the timing relationship between two signals, or between a specific vibration event and a keyphasor pulse. Phase Reference - A signal used in rotating machinery measurements, generated by a sensor observing a once-per-revolution event. Phase Response - The phase difference (in degrees) between the filter input and output signals as frequency varies; usually expressed as lead and lag referenced to the input. Phase Spectrum - Phase frequency diagram obtained as part of the results of a Fournier transform. POINT - Defines a machinery location at which measurement data is collected and the measurement type. Probe - An eddy-current sensor, although sometimes used to describe any vibration sensor. Probe Gap - The physical distance between the face of an eddy probe tip and the observed surface. The distance can be expressed in terms of displacement (mils, micrometers) or in terms of voltage (millivolts), which is the value of the (negative) dc output signal and is an electronic representation of the physical gap distance. Standard polarity convention dictates that a decreasing gap results in an increasing (less negative) output signal; increasing gap produces a decreasing (more negative) output signal. Radial - Direction perpendicular to the shaft centerline. Radial Position -The average location, relative to the radial bearing centerline, of the shaft dynamic motion. Radial Vibration - Vibration that is perpendicular to a shaft's centerline. Resonance - The condition of vibration amplitude and phase change response caused by a corresponding system sensitivity to a particular forcing frequency. A resonance is typically identified by a substantial amplitude increase, and related phase shift. RMS - The square root of the sum of a set of squared instantaneous values. ROUTE - A measurement POINT collection sequence. Run Up/Run Down - The monitoring of machinery conditions during a start up or shut down process. Sensitivity - The ratio of magnitude of an output to the magnitude of a quantity measured. Also the smallest input signal to which an instrument can respond. Sensor - A transducer that senses and converts a physical phenomenon to an analog electrical signal.

Glossary Model 258 User Manual

Setpoint - (See alarm setpoint.) Signal Analysis - Process of extracting information about a signal's behavior in the time domain and/or frequency domain. Describes the entire process of filtering, sampling, digitizing, computation, and display of results in a meaningful format. Spectrum - A display of discrete frequencies and their amplitudes. Spectrum Analyzer - An instrument that displays the frequency spectrum of an input signal. Thermocouple - A temperature sensing device comprised of two dissimilar metal wires which, when thermally affected (heated or cooled), produce a change in electrical potential. Time Domain - A dynamic amplitude vs. time graph. Time Waveform - (See Waveform.) Transducer - A device that translates a physical quantity into an electrical output. Trend - The measurement of a variable vs. time. Trigger - Any event, which can be used as a timing reference. Upload - Transferring data from the measuring device to the host computer. Vibration - The behavior of a machine's mechanical components as they react to internal or external forces. Magnitude of cyclic motion; may be expressed as acceleration, velocity, or displacement. Defined by frequency and timebased components. Waveform - A presentation or display of the instantaneous amplitude of a signal as a function of time.

Model 258 Glossary User Manual

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