eet 3136 electrical drives - foe.mmu.edu.myfoe.mmu.edu.my/lab/lab sheet/lab sheet sem 3...
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EET 3136
Electrical Drives
Experiment # 1
LOAD CHARACTERISTICS OF INVERTER FED
INDUCTION MOTOR
Experiment # 2
PARAMETER SETTING OF AN INDUSTRIAL VARIABLE
SPEED DRIVES
Note: On-the-spot evaluation is carried out during or at the end of the experiment. Students
are advised to read through this lab sheet before doing experiment. Your performance,
teamwork effort, and learning attitude will count towards the marks.
Caution 1. This experiment deals with voltage supply of 415V,50Hz
2. Students will be provided with a technical manual of the system.
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Experiment # 1
LOAD CHARACTERISTICS OF INVERTER FED
INDUCTION MOTOR
Part A: (10.71.2) Setting Parameters to the Frequency Range
Part B: (10.71.4) Load Characteristic of Inverter Fed Induction Motor
Reference
ELWE – GB 51 10 062 49/99
Setting Parameters to the Frequency Range: 10.71.2
OBJECTIVE The frequency of the frequency inverter should be adjustable between 10 Hz and 80 Hz.
The acceleration and deceleration should be as immediate as possible when the rotational
frequency setting is changed. The other parameters should conform to the standard settings
of the manufacturer. The settings required for this are to be on the frequency inverter and
checked.
REQUIREMENT EQUIPMENT
Experimental panel system
Unit description 1000 W
Frequency inverter control unit 10 10 076
Frequency inverter power unit 10 10 072
Connection cable LT/ST 15 10 015
Connection cable 55 00 307
Interface operator 15 10 013
Shaft-end cover 31 00 005
Three-phase squirrel-cage induction motor 30 27 600
Connection mask 31 25 601
PROCEDURE
1. Connecting the motor
1.1 For safety reasons, cover the motor shaft by attaching the safety guard.
1.2 Connect the motor to the frequency inverter, incl. PE.
1.3 How are the coils of the motor with a rated voltage 230/400 V to be connected to
ensure that the motor can be operated at its rated values on the frequency inverter with
one phase input to 230V mains?
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2. Commissioning the frequency inverter
2.1 Make the basic settings described above. Connect the frequency inverter to the
mains and move the mains switch to "“on"”
Describe the behavior of the motor on changing the set point value.
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2.2 Describe briefly what basic settings are to be made on the frequency inverter before
commissioning.
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3. Assigning parameters to the frequency inverter
3.1 The settings which are required on the frequency inverter in order to be able
complete the parameter assignment:
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3.2 Enter the necessary steps in the table which will allow you to assign parameters to
the frequency inverter in order to complete the task.
Settings Display Function
noP
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- Connect control inputs for controller enabling (! Enabling direction of
rotation, internal set point)
4. Check parameter assignment
4.1 Describe the results of the check.
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4.2 Disconnect the control inputs controller enabling, setting of the standard values
specified by the manufacturer.
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Part B: (10.71.4) Load Characteristic of Inverter Fed Induction Motor
OBJECTIVE The dependence of the rotational frequency of a three-phase squirrel-cage induction
monitor on the torque at various frequencies of the output voltage of the frequency inverter
is to be examined.
REQUIRED EQUIPMENT
Experimental panel
system
Unit description 1000 W
Frequency inverter control unit 10 10 076
Frequency inverter power unit 10 10 072
Connection cable LT/ST 15 10 015
Connection cable 55 00 307
Interface operator 15 10 013
Pendulum machine 30 27 000
Brake control unit 67 10 611
Three-phase squirrel-cage induction motor 30 27 600
Connection mask 31 25 601
Coupling collar 31 00 000
Coupling cover 31 00 003
Shaft-end cover 31 00 005
Arrange the instruments according to the illusion.
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PROCEDURE
1. Putting into operation
1.1 Connect the pendulum machine and the motor with help of the coupling collar.
Positioning the safety guards.
1.2 Connect the brake control unit including the temperature sensor for the motor and
make the following basic settings:
- Rotational frequency range 1500/ 3000 rpm
- Torque range
- Function off
1.3 Switch on the brake control unit using the mains switch. Press the reset button. If the
red LED is still alight now, there must be a fault in the set-up, e.g.
- the coupling safety guard is missing
- the safety guard for the shaft-end cover is missing
- the jack plug for the temperature control of the motor has not been inserted
- the motor is too hot
1.4 Connect the motor according to its rated voltage to the frequency inverter with the
frequency inverter being switched off, including PE.
1.5 Switch on the frequency inverter and make the following basic settings:
- CP. 5 Rated frequency 50 Hz
- CP. 6 Boost 0%
- CP. 7 Acceleration time 0.1 seconds
- CP. 8 Deceleration time 0.1 seconds
- CP. 9 Minimal frequency 0 Hz
- CP. 10 Maximal frequency 100 Hz
- CP. 18 Slip compensation off off
- CP. 19 Auto boost off
- CP. 1 Actual frequency display
2. Load capacity of the motor
2.1 How does the power given off to the shaft of the motor increase with the rotational
frequency whilst the load torque remains constant?
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2.2 Why may a self-ventilated motor not be loaded with its rated torque permanently at
low rotational frequency?
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3. M = f ( n ) Characteristic curves of a three-phase squirrel-cage induction motor
with two pairs of poles
3.1 Find the rotational frequency of the motor at the prescribed frequencies of the
frequency inverter (parameters) dependent on the motor’s load. Connect controller
enabling. (Release of direction of rotation F!, internal setpoint)
Set “man., nconst.” On the brake with “down” (“up”) the torque values. Enter your
findings in the table.
At the end of the test series set to “off” mode and disconnect the controller release.
Boost: 0%
M
Nm
F
Hz
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
10
20
30
40
50
60
70
80
90
100
Rotational frequency in rpm
3.2 Repeat the series of measurements outlined in 3.1.
Boost: 25%
M
Nm
F
Hz
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
10
20
30
40
50
60
70
80
90
100
Rotational frequency in rpm
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3.3 Draw the M = f ( n ) characteristic curves on the basis of your findings.
3.4 Compare the change in slip with the motor under load in the armature range and in
the field attenuation and field control range.
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3.5 Compare the change in the breakdown torque in the armature range and in the field
attenuation and field control range when the frequency is changed.
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3.6 Why does to achievable torque of the monitor below the rated frequency without
boost decrease at lower frequencies?
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3.7 Why does achievable torque of the motor remains constant up to the rated frequency
when a “boost” is set appropriately?
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3.8 What causes the reduction of the achievable torque when the frequency is increased
above the rated frequency?
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Experiment # 2
PARAMETER SETTING OF AN INDUSTRIAL VARIABLE
SPEED DRIVES
1.0 THEORY
1.1 Variable Speed Drives Variable Speed Drive (VSD), in its simplest form, is a block, which can supply varying
power at the terminals of a motor. When used with an AC induction motor, VSD operates
based on the principle that the synchronous speed on the motor is given by
p
f120NS = (1)
Where NS is the speed in revolutions per minute (rpm), f is the frequency in Hz and p the
number of electrical poles of the motor. The VSD varies the frequency in (1) to vary the
speed of the motor. A range of VSDs is available commercially for use in the industry and
listed below are some of the applications, which may seem cumbersome without the use of
VSDs.
Schneider Electric’s VSDs series, the ATV18 series, includes among other useful functions
the 4 Preset Speeds function. This function makes use of two of the logic inputs (LI) of the
ATV18 to easily select any of the four speeds combinations at which the motor may be
operated. Figure 1 illustrates one of many 4 Preset Speed configurations.
HSP
SP4
SP3
LSP
0
ACC DEC
Four Preset Speeds settings
LSP and HSP are low speed and high speed respectively, which are the two basic control
speeds of the ATV18; SP3 and SP4 are the additional 3rd
and 4th
preset speeds.
1.2 Conveyor Belt Conveyor belts are used to move a continuous mass from one place to another within a
compound. Conveyor belts are a necessity in many industries where use of human labor
would result in degraded efficiency. The movement of the conveyor belt is driven by a
motor, which in most cases allows a certain degree of control to add flexibility to the flow
of the mass being transported. In mining industry conveyor belts are used to transport
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rocks from underground, in automobile industry parts are conveyed using belts and in food
industry these belts are used to pass food through washers and driers.
1.3 Ventilation Ventilation is an air exchanging process that brings air into a building and exhausting
contaminated air. Contaminated air can be hot air, cold air or even intoxicated air
depending on the application. There are quite a few types of ventilation systems out there
and each of these systems is composed of three main components, which are inlets, fans
and controllers. The motors running as fans in these systems should, among other things,
have the capability to run at different speeds and have optimum performance when
operated at low speeds.
1.4 Textile Machine A textile machine transforms many single threads into a cloth. The threads, which may be
of different colors and textures, are held on rods called spindles. The spinning motion of
the spindles is driven by a motor, which can run at high speeds in both directions. The
spindle would rotate at low speed with high load torque when it is full; and high speed with
low load torque when it is almost empty. Synchronization of speed and tension between
spindles is critical. Thread breakage may happen as a result of poor synchronization.
2.0 APPARATUS - ATV18-MMU
- 1.5kW Squirrel Cage Induction Motor
- Stroboscope
- Connecting Cables
2.1 General Procedure To carry out this experiment, a connection of ATV18-MMU to Power Supply and motor
must be made. Please refer to the manual provided to make these connections.
1) Put all the logic input switches (SLIs) at OFF (0) position. This is necessary to
prevent the motor from running unexpectedly.
2) Depress the start button(SW1) and hold for 3 seconds until the red light vanishes. If
there is fault the red light will continue to glow and a fault message will be shown
on the Display on the ATV18, please refer on the ATV18-MMU [page 15-16] on
how to remedy the fault.
3) To RETURN all parameters to their Factory Preset Value. Go to FCS (second level
parameter) and set to YES and follow by ENT. This will initialize all parameters as
given in ALTIVAR 18 manual [Page 57-62]. Repeat Step 2.
4) Proceed with the experiment (Lab A-D)
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2.4.1 Lab A: 4 PRESET SPEEDS
Note: To set the parameters, use down and up arrow, and press data button at
respective parameters, use the down, and up arrow again to change the values/setting.
Save the changes by pressing ENT.
1. Using the Keypad and Display terminal, go to LI3 and set it to PS2. Note: Since LI3 is
a second level parameter, it may not appear in the menu; please refer to ATV18-MMU
manual to see how to enable level 2 parameters.
2. Go to LI4 and set it to PS4
3. Go to the following parameters and set the values as stated:
ACC = 5
DEC = 13
LSP = 6
HSP = 60 SP3 = 15
SP4 = 30
4. Close SLI1, the logic input 1. (The motor will rotate at the set frequency in the forward
direction). To monitor the frequency of rotation of the motor on the Display, go to rFr
using the Keypad and press DATA.
5. Use logic input switches SLI3 and SLI4 to select different motor speeds and record
their logic combinations in the table A1.
Table A1
SLI3
(1/0) SLI4 (1/0)
Assignment
on motor
Speed (Hz) Measured Speed*
(RPM)
• Set the analog setpoint to 0 (the ref. potentiometer)
• Using Stroboscope (Only for speed more than 10Hz)
2.4.2 LAB B: APPLICATION 1- CONVEYOR BELT
During this lab you will be introduced to most commonly used function parameters in
conveyor belt system such as those that convey bottles in a factory.
In this experiment we shall look at
1) Application functions
Acceleration and decelerations ramp
Preset Speeds
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2) Common problems
Resonant frequency
Fault Clearance by logic input
Procedures 1. Reset the VSD setting to factory presets by ENTering YES to FCS.
You will have to power up the VSD using the Start button after resetting the system to
factory presets
2. Switch ON SLI1 and observe the rotation of the motor. You need to increase the ref
(potentiometer if necessary)
3. Observe the acceleration (ACC) of the motor. It should accelerate in 3s since it’s a
factory preset.
4. Start the motor again by setting SLI1 to 1 (ON), then observe the acceleration, after
a while, set the L1 to 0 (OFF) then observe the deceleration. Your instructor will probably
show you a simulation of what is happening.
In the bottling industry, bottles on the conveyor belt often have to temporarily stop to be
filled up and then take off again. The acceleration and deceleration of the motor will
determine how steady will be the bottles on the belt during those starts and stops. The
factory presets are definitely not suitable for bottling application.
5. Increase both ACC and DEC to 6s and observe the difference from factory preset
settings
Extremely high values of ACC and DEC lengthen the bottling cycle time
Bottles may have to run at different speeds in between the stops in order to optimize the
bottling process. For ATV18, values set for ACC and DEC determine how well the four
preset speeds are coordinated to smoothly run the process.
6. Factory preset setting assigns logic input LI3 and LI4 to control of preset speed.
The value of these speeds of factory setting can be changed using parameters SP3 and SP4.
In this case, set SP3 to 10Hz and SP4 to 35Hz.
7. With ACC and DEC still set at 6s, use logic switches SLI3 and SLI4 to select
among the LSP, HSP, SP3 and SP4.
While observing the speed change, notice on the ATV18 display that the frequency
gradually changes to the selected value and it does so with increments/decrements of 0.1
Hz. The changing frequency, while trying to reach the selected value, it may interfere with
the resonant frequency of the surrounding system here degrading the conveyor’s operation.
For some conveyor belt systems, the critical frequency is 43 Hz (arbitrarily chosen).
Resonance frequency of conveyor system is usually determined by observing the conveyor
runs at various speeds. The conveyor tends to vibrates and run noisier when it resonate.
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8. Set JPF to 43Hz. Put both SLI3 and SLI4 at OFF positions while keeping SLI1 at
ON position.
9. With frequency of operation displayed on the ATV18, use the analog ref to
gradually vary the frequency from LSP to HSP.
Note: You can identify this frequency using parameter “ rFr ” during acceleration and
deceleration.
2.4.3 Lab C: APPLICATION 2- VENTILATION
During this lab you will be introduced to most commonly used function in ventilation
system
Application functions
Acceleration ramp
Low speed
Preset Speeds
Noise Reduction
Common problems
Catching a spinning load
Resonant Frequency
Procedures 1. Using the Keypad and Display terminal on the ATV18, find a second level
parameter LI3 in the parameter list and set it to PS2. Assign OFF to both LI2 and LI4
parameters.
(Note: If the logic inputs-LI2, LI3 and LI4-parameters are not available in the list you may
have to enable them, please refer to the manual provided).
2. Start the “Fan” (motor) using the logic inputs. (Recall the assignment of these logic
inputs).
Write down what happen when each of logic inputs activated (logic 1).
SLI1 (LI1)………………………………………………………………………..
SLI3 (LI3)………………………………………………………………………..
3. In order to start the fan as quickly as possible, you can reduce the acceleration
ramp. Depending to the fan inertia this may cause an erratic run up to speed. If this occurs
the acceleration ramp is not followed. You can resolve this problem by extending the ramp
time and modifying the gain FLG.
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To simulate a high inertia fan, start the motor and let it run at 50Hz. Go to ‘LCr’ and
monitor the current value while applying load to the shaft. Apply load till current value
indicated is 4A. Now Stop the motor.
Set the ACC to 1s run the motor (arbitrarily count how many second it takes to reach max
speed). Try to set ACC to 1s and set gain FLG to 20%. Observe the differences.
4. Fans are normally used for maintain good quality of the air. If the degree of
pollution is low the fan runs at low speed LSP. Low speed is always relatively high to
maintain efficiency.
Set the LSP to 25Hz and observe. Make sure the “ref” is set to 0.
5. When the degree of pollution increases (eg. Underground car park), the speed
controller automatically changes the high speed HSP to enable removal of polluted air.
This change the high speed is initiated by switching a logic input SLI3 (LI3) in this
example.
Start the fan (SLI1). Motor runs at Low speed (LSP). Activate LI3 and Observe. Normally
the LI3 will be controlled by a sensor e.g. CO2 sensor
6. Motor noise caused by switching frequency may be unacceptable particularly in
area where comfort is a priority, for example in air-conditioning system or hospital. You
have a possibility of reducing this noise level by selecting a high switching frequency
using parameter SFr.
By default the switching frequency is SFr = 4kHz. Change the switching frequency from
4kHz to 8kHz and then to 12kHz..
(Note: SFr can be configured on the fly, i.e. it can be configured while the motor is running
(SLI1 at logic 1)
7. During a short supply interruption, the fan changes the free wheel operation. When
the supply comes back ON, the speed controller stops the fan to restart. This causes jolting,
which may damage the machinery particularly when the inertia is high. To prevent this
phenomenon you can select catching spinning load. When the supply is switch back ON
the fan is restarted at the level of speed calculated by speed controller.
a. Using Keypad and Display terminal, set LSP and HSP to 0 and 50 Hz
respectively
b. Start the motor in a forward direction by activating SLI1.
c. Increase the ‘ref’ input until the speed of the motor is at set maximum
HSP.
d. While observing the rotational motion of the motor, depress STOP
button followed by START allowing 2s between the state transitions
e. Using Keypad and Display terminal, find SPr parameter and set YES to
it to activate the automatic spinning load catching function with speed
search
f. Repeat step 7(d)
2.4.4 Lab D: APPLICATION 3- TEXTILE MACHINE During this lab you will be introduced to some of the most commonly used function in
textile machines
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Application functions
2 directions of operation
JOG
Fast stop
Common problems
Stop on ramp on power failure
Catching a spinning load
Procedures Each of the functions in this section is activated or deactivated using a single Logic Input
of the ATV18. The first logic input (LI1), for instance, is assigned permanently to run the
motor in forward direction while other Logic Inputs can be assigned any of the other
functions supported by ATV18. Since some of its functions do the opposite of what other
functions do, ATV18 sets functions priority to maintain its operational integrity.
1. With SL1 to SLI4 at position 0, use the Keypad and Display terminal to set the HSP
parameter to 25 Hz and assign rrS to LI2 while making sure that OFF is assigned to
both LI3 and LI4.
2. Increase the analog reference to 10V (Maximum).
3. Start the motor by putting SLI1 at logic 1. (Notice the direction of rotation of the
motor).
a) With the motor still running, put SLI2 at logic 1. What happens to the
direction of torque of the motor?
b) Put SLI1 back to logic 0. Is the direction of rotation still the same?
c) Put SLI2 at logic 0 to stop the motor.
d) Set SLI2 to logic 1 and notice the direction of rotation.
e) With the motor still running, switch SLI1 to logic 1. Does the direction of
rotation change?
f) Put SLI2 back to logic 0. Does the direction of rotation change?
4. Using Keypad & Display terminal, set LI3 parameter to JOG.
A low speed adjustment function is commanded by logic input LI3. Also to enable starting
inputs LI1 and LI4 must be activated. If logic input LI4 is deactivated its commands the
machine to stop. This is positive safety feature, if the supply fails the machine stops.
5. JOG. This function enables the machine to be set up at low speed. The acceleration and
deceleration ramps are set at 0.1s if logic input LI3 is activated before LI1. If LI1 is
activated before LI3 it is ramp settings that are used.
Set the JOG function to 5Hz. Start the motor by activating LI3 and then LI1. Then try
to start the motor by LI1 and after LI3. Observe the differences.
6. On the power failure, it is necessary to keep the thread tense, hence to maintain a
deceleration ramp. Validate the stop on supply failure function STP = YES (stop on
ramp). Basically the energy stored in the speed controller enables deceleration take
place following the ramp in spite of power failure.
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Set STP = YES .Start the motor LI1 once it reaches maximum speed, switch off the
power supply by depressing stop button (SW2).
7. Catching a spinning load ;this function is used during short power interruption to
calculate the speed of rotation of the motor and take this into account on restarting.
Without this function restarting begins at zero speed.
Set the SPr = YES. On the motor (LI1) and try to create power supply interruption as
created in Lab C- Step 7.
Exercises
For Lab A Calculate Slip when the motor runs at these switches’ combinations.
a) SL3=1, SL4=1
b) SL3=0, SL4=1
For Lab B What is the range of frequencies that are skipped by ATV18-MMU in step 9?
For Lab C a. In Step 6, explain the differences found as switching frequency increased.
b. In Step 7, what are differences observed by enabling SPr. Explain what would happen
to the system if the feature is not available?
Lab D a. Referring to Step 3. What can you say about the priorities of forward and reverse
function?
Write in your own words, how does a variable speed drive help to save energy in industry?
Marking Scheme for experiment 1
Lab-1
(10
marks)
Assessment
Components
Details
Hands-On & Efforts
(2.5 marks)
Lab assessments are done based on the hands-on
capability of the students and their efforts during the lab
sessions.
On the Spot
Evaluation (2.5
marks)
On the spot evaluations based on the theory concerned
with the lab experiments and the observations are done
for students.
Lab Report
(5 marks)
Student should submit a hard copy lab-report after 3
days of performing the lab experiment. The lab-report
consists of introduction, recorded experiment data,
discussion, and conclusion. The experiment may be
done by the team working of 2-3 students, but the lab-
report preparation is done individually.
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Marking Scheme for experiment 2
Lab-2
(10
marks)
Assessment
Components
Details
Hands-On & Efforts
(2.5 marks)
Lab assessments are done based on the hands-on
capability of the students and their efforts during the lab
sessions.
On the Spot
Evaluation (2.5
marks)
On the spot evaluations based on the theory concerned
with the lab experiments and the observations are done
for students.
Lab Report
(5 marks)
Student should submit a hard copy lab-report after 3
days of performing the lab experiment. The lab-report
consists of introduction, recorded experiment data,
discussion, and conclusion. The lab-report preparation is
done individually.
An average total marks of Lab-1 and Lab-2 will be considered as 10% for final marks.