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Automatic Transfer Switch: Model ATS-NWInterruptor de transferencia automática, modelo ATS-NWInterrupteur de transfert automatique,modèle ATS-NWClass / Clase / Classe 2700

Instruction BulletinBoletín de instruccionesDirectives d'utilisation

80332-001-03Retain for Future Use. / Conservar para uso futuro. / À conserver pour usage ultérieur.

Instruction Bulletin

80332-001-03Retain for future use.

Automatic Transfer Switch: Model ATS-NWClass 2700

HAZARD CATEGORIES AND SPECIAL SYMBOLS

Read these instructions carefully and look at the equipment to become familiar with the device before trying to install, operate, service or maintain it. The following special messages may appear throughout this bulletin or on the equipment to warn of potential hazards or to call attention to information that clarifies or simplifies a procedure.

The addition of either symbol to a “Danger” or “Warning” safety label indicates that an electrical hazard exists which will result in personal injury if the instructions are not followed.

This is the safety alert symbol. It is used to alert you to potential personal injury hazards. Obey all safety messages that follow this symbol to avoid possible injury or death.

PLEASE NOTE Electrical equipment should be installed, operated, serviced, and maintained only by qualified personnel. No responsibility is assumed by Schneider Electric for any consequences arising out of the use of this material.

DANGERDANGER indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.

WARNINGWARNING indicates a potentially hazardous situation which, if not avoided, can result in death or serious injury.

CAUTIONCAUTION indicates a potentially hazardous situation which, if not avoided, can result in minor or moderate injury.

CAUTIONCAUTION, used without the safety alert symbol, indicates a potentially hazardous situation which, if not avoided, can result in property damage.

Provides additional information to clarify or simplify a procedure.

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80332-001-03 Automatic Transfer Switch: Model ATS-NW07/2007 Table of Contents

© 2003–2007 Schneider Electric All Rights Reserved 3

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TABLE OF CONTENTSIntroduction ................................................................................................ 7

Safety Precautions..................................................................................... 8

Receiving, Handling, and Storage............................................................ 8

Applications and Specifications............................................................... 8

Main-Main ................................................................................................... 8Main-Generator ........................................................................................... 9Operator Door Assembly .......................................................................... 10

Operating Mode Group: Main-Main ..................................................... 10Indicator Lights .............................................................................. 11Preferred Source Selector (PSS) (Optional).................................. 11Auto/Manual Keyed Switch............................................................ 11Auto Retransfer (Optional)............................................................. 11

Operating Mode Group: Main-Generator ............................................ 12Indicator Lights .............................................................................. 12Exercise with Load (Optional)........................................................ 12Auto/Manual Keyed Switch............................................................ 12Generator Start/Stop ..................................................................... 12

Source and UPS Status Group ........................................................... 13Indicator Lights .............................................................................. 13Test Transfer Switch...................................................................... 13Push-To-Test Button (Optional)..................................................... 13

Circuit Breaker Control and Status Group ........................................... 14Indicator Lights .............................................................................. 14Pushbuttons................................................................................... 14

Control Power and Power Monitor Assembly ........................................... 14Control Power Subassembly ............................................................... 14Power Quality Monitor Subassembly .................................................. 14

Generator Relay Subassembly ................................................................. 15Sync-Check Relay Assembly .................................................................... 15UPS Assembly .......................................................................................... 16

Control Power Source Contactor ......................................................... 16UPS Bypass Relay .............................................................................. 16UPS Unit .............................................................................................. 17

Programmable Logic Controller (PLC) assembly ...................................... 17Disconnects and Fuses ....................................................................... 18Interposing Relays ............................................................................... 18Remote Status Relay Subassembly .................................................... 19Generator Start Relay ......................................................................... 19

Touch Screen Control Option ................................................................... 20General Information ............................................................................. 20Touch Screens .................................................................................... 20Main Screen ........................................................................................ 20Settings Screen ................................................................................... 21PLC I/O Map ........................................................................................ 21Alarm Log (Optional) ........................................................................... 21Event Log (Optional) ........................................................................... 22Password Access ................................................................................ 22Control Operation ................................................................................ 23Control Settings ................................................................................... 23Alarm and Event Logs (Optional) ........................................................ 23

Mechanical Interlocking Cable Assembly ................................................. 24Open Transition ................................................................................... 24closed transition .................................................................................. 24

Automatic Transfer Switch: Model ATS-NW 80332-001-03Table of Contents 07/2007

© 2003–2007 Schneider Electric All Rights Reserved4

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Operation .................................................................................................. 24

Main-Main System .................................................................................... 24Initial (Default) Setting ......................................................................... 24Normal Source Lost ............................................................................. 24Normal Source Returns—PSS Off/ No PSS Option ............................ 24Normal Source Returns—PSS On ...................................................... 24Alternate Source Lost .......................................................................... 24Auto Retransfer (Optional) ................................................................... 24

Main-Generator System ............................................................................ 24Initial (Default) Setting ......................................................................... 25Normal Source Lost ............................................................................. 25Normal Source Returns—Open Transition .......................................... 25Normal Source Returns—closed transition ......................................... 25Generator Source Lost While Normal Source Is Out ........................... 25Exercise Period ................................................................................... 25

Conditions That Prevent Transfer of Source ............................................. 25Downstream Fault ............................................................................... 25Other Conditions .................................................................................. 25

Installation ................................................................................................ 26

Preparation for Receiving Equipment ....................................................... 26Location and Interconnection of Assemblies ............................................. 26Final Wiring Connections .......................................................................... 26Installing the Equipment ............................................................................ 26Checkout Before Energizing ..................................................................... 26Performance Checkout ............................................................................. 27Placing Into Service .................................................................................. 27Test Procedures ........................................................................................ 28

Main-Main Base System ...................................................................... 28Manual Mode ................................................................................. 28Automatic Mode............................................................................. 29

Main-Main Standard Options ............................................................... 30Manual Mode ................................................................................. 30Automatic Mode............................................................................. 31

Main-Generator Base System ............................................................. 32Manual Mode ................................................................................. 32Automatic Mode............................................................................. 33

Main-Generator Standard Options ...................................................... 34Manual Mode ................................................................................. 34Automatic Mode............................................................................. 35

Troubleshooting and Maintenance ........................................................... 36

Changing Fuses ........................................................................................ 36Checking Light Bulbs ................................................................................ 36

With Push-To-Test Option ................................................................... 36With No Push-To-Test Option ............................................................. 36

Troubleshooting Chart ............................................................................... 37List of Standard Values and Arrangements .............................................. 38

All Systems .......................................................................................... 38Generator Systems ................................................................................... 38Connection to Circuit Breakers ................................................................. 39

Connection to Circuit Breakers ............................................................ 39References ................................................................................................ 39

Maintenance Log ...................................................................................... 40

80332-001-03 Automatic Transfer Switch: Model ATS-NW07/2007 List of Figures


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LIST OF FIGURES Figure 1: PLC Shown on Power-Style® QED Switchboard .................. 7Figure 2: Main-Main Configuration ....................................................... 9Figure 3: Main-Generator Configuration ............................................... 9Figure 4: Operator Door—Basic Main-Generator Configuration ........ 10Figure 5: Operating Mode Group: Main-Main ..................................... 10Figure 6: Operating Mode Group: Main-Generator ............................ 12Figure 7: Source and UPS Status Group ........................................... 13Figure 8: Circuit Breaker Control and Status Group ........................... 14Figure 9: Generator Relay Subassembly ........................................... 15Figure 10: Sync-Check Relay Assembly .............................................. 15Figure 11: UPS Assembly .................................................................... 16Figure 12: Control Power Source Contactor ......................................... 16Figure 13: UPS Bypass Relay .............................................................. 16Figure 14: UPS Unit .............................................................................. 17Figure 15: PLC Assembly ..................................................................... 17Figure 16: Disconnects and Fuses ....................................................... 18Figure 17: Interposing Relays ............................................................... 18Figure 18: Remote status relay ............................................................ 19Figure 19: Generator Start Relay ......................................................... 19Figure 20: Main Screen ........................................................................ 20Figure 21: Settings Screen ................................................................... 21Figure 22: PLC I/O Map Screen ........................................................... 21Figure 23: Alarm Log Screen ................................................................ 21Figure 24: Event Log Screen ................................................................ 22Figure 25: Password Access ................................................................ 22

Automatic Transfer Switch: Model ATS-NW 80332-001-03List of Tables 07/2007


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LIST OF TABLES Table 1: Manual Mode Test Procedures for Basic Main-Main........... 28Table 2: Automatic Mode Test Procedures for Basic Main-Main....... 29Table 3: Manual Mode Test Procedures for Main-Main

with Options......................................................................... 30Table 4: Automatic Mode Test Procedures for Main-Main

with Options......................................................................... 31Table 5: Manual Mode Test Procedures for Basic Main-Generator .... 32Table 6: Automatic Mode Test Procedures for Basic Main-Generator .. 33Table 7: Manual Mode Test Procedures for Main-Generator

with Options......................................................................... 34Table 8: Automatic Mode Test Procedures for Main-Generator

with Options......................................................................... 35Table 9: Troubleshooting................................................................... 37Table 10: System Settings................................................................... 38Table 11: System Configuration .......................................................... 38Table 12: Generator System Settings.................................................. 38Table 13: Maintenance Log Table ....................................................... 40

80332-001-03 Automatic Transfer Switch: Model ATS-NW07/2007 Introduction


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Introduction This instruction bulletin describes Main-Main and Main-Generator Square D® brand automatic transfer switches for low voltage switchboards/switchgear. It is for use by installers and specifiers and describes standard systems. For installations that deviate from these standards, this bulletin provides basic information only. Standard systems always include an uninterruptible power supply (UPS).

Options available are a preferred source selector switch, closed transition, and push-to-test lights. Refer to documentation supplied by the factory for any deviations to the standard system.

This bulletin also describes a standard sequence of operation for the programmable logic controller (PLC) system. The standard sequence follows one of the topics in “Operation” on page 24 of this manual. The system is checked for proper sequence using one of the “Test Procedures” starting on page 28 of this instruction bulletin. Any changes to the standard sequence are documented in separate instructional materials provided by the factory.

Square D brand automatic transfer switches from Schneider Electric are designed to meet Underwriters Laboratories® (UL®) 1008 and to be applied on National Electrical Code® (NEC®) 700, “Emergency Systems.” They are also applicable to NEC 701 “Legally-Required Standby Systems” and 702 “Optional Standby Systems.”

This transfer switch is suitable for control of motors, electric discharge lamps, tungsten filament lamps, and electric heating equipment where the sum of motor full-load ampere ratings and the ampere ratings of other loads do not exceed the ampere rating of the switch, and the tungsten load does not exceed 30 percent of the switch rating.

Figure 1: PLC Shown on Power-Style® QED Switchboard

Automatic Transfer Switch: Model ATS-NW 80332-001-03Safety Precautions 07/2007


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Safety Precautions

Receiving, Handling, and Storage

The automatic transfer switch is included as part of already-assembled equipment. Refer to the general equipment instruction bulletin for complete receiving, handling, and storage instructions for the equipment. Also refer to the programmable controller’s user guide for additional environmental restrictions.

Applications and Specifications

Automatic transfer switch systems minimize power interruption by transferring the load from the normal source to an alternate source when the normal source is temporarily unavailable. The system uses multiple connections to power sources (at least one of which is a utility) and a control system to achieve this transfer.

This transfer system may be supplied with mounted or drawout circuit breakers, and is controlled by a Modicon® programmable logic controller. These systems also feature redundant supplies of control power.

Main-Main Each main circuit breaker connects to a utility source. Either supply may be the emergency or alternate source. When the normal source becomes unavailable, the system transfers to the alternate source. If the system is equipped with a PSS option, the system reverts to the preferred source automatically once it is available. Without the selector, automatic retransfer does not occur. See Figure 2.

DANGERHAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

• Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E.

• This equipment must only be installed and serviced by qualified electrical personnel.

• Turn off all power supplying this equipment before working on orinside equipment.

• Always use a properly rated voltage sensing device to confirm power is off.

• Replace all devices, doors and covers before turning on power to this equipment.

Failure to follow these instructions will result in death or serious injury.

CAUTIONHAZARD OF BODILY INJURY OR EQUIPMENT DAMAGE

• This manual contains general information about a standard design. It does not contain information about modifications to the standard design.

• Thoroughly review all documentation supplied by the factory for any deviations to the standard design.

• Contact your local Schneider Electric representative if you have any questions concerning the automatic transfer switch.

Failure to follow these instructions can result in injury or equipment damage.

80332-001-03 Automatic Transfer Switch: Model ATS-NW07/2007 Applications and Specifications


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Main-Generator One main circuit breaker connects to a utility source. The other main circuit breaker connects to a standby generator. Either main can be the emergency source. When power from the utility source is lost, the generator starts. Once both frequency and voltage stabilize, the system will transfer to the generator. The system reverts to the utility source automatically when it becomes available, and the generator start signal is discontinued. See Figure 3.

Figure 2: Main-Main Configuration

Left main

Right main

Common load

PLC

Utility 1 Utility 2

Figure 3: Main-Generator Configuration

Left main

Right main

Common load

PLC

Utility 1 Generator

Automatic Transfer Switch: Model ATS-NW 80332-001-03Applications and Specifications 07/2007


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Operator Door Assembly The operator door features indicating lights, pushbuttons, and keyed switches used to interface with the control system. See Figure 4. The main-generator system features an additional generator switch. Except as noted, the keys may be removed in any position. The location of lights and switches may vary depending on equipment type and options included. The lights and switches will always be clearly labeled.

Operating Mode Group: Main-Main The upper left-hand corner of the operator door features a two-position auto/manual keyed switch and three indicator lights. Two other optional keyed switches may be present.

Figure 4: Operator Door—Basic Main-Generator Configuration

Figure 5: Operating Mode Group: Main-Main

1. White Indicator Light

2. Blue Indicator Light

3. Amber Auto Mode Fail Light

4. PSS Switch (Optional)

5. Auto/Manual Keyed Switch

6. Auto Retransfer Switch (Optional)

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Indicator Lights The white light (Figure 5, 1) indicates the system is in Automatic mode. The blue light (Figure 5, 2) indicates the system is in Manual mode. The auto/manual keyed switch determines the operating mode.

The amber auto mode fail light (Figure 5, 3) indicates a system irregularity. The amber auto mode fail light illuminates under any of the following circumstances:

• Either drawout main circuit breaker (but not all) has been racked to the test or disconnect positions

• Either main circuit breaker has tripped while the system was in Automatic mode for a reason (such as ground fault) that prevents transfer of source

• A mechanical Open pushbutton has been pressed

• The internal diagnostics have detected an error

Preferred Source Selector (PSS) (Optional) The optional PSS (Figure 5, 4) is a three-position keyed switch that determines whether the left or right source is the normal source. The center position is the Off position

Auto/Manual Keyed Switch The auto/manual keyed switch (Figure 5, 5) has two positions. Turn the key to:

• “Auto” for automatic operation.

• “Man” (manual) to use the pushbuttons on the operator door to control the system manually.

Auto Retransfer (Optional) The optional auto retransfer selector (Figure 5, 6) is a two-position keyed switch that determines the automatic retransfer mode. In the On position, retransfer occurs automatically after a source returns and becomes stable. In the Off position, the system remains in the transferred state after the source returns, allowing the user to manually initiate the retransfer at a more convenient time. Move the switch from the Off position to On to begin the transfer sequence. When transfer is complete, return the switch to the Off position, if automatic transfers are not desired.

If the auto retransfer switch is not supplied, all retransfers will be automatic.



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Operating Mode Group: Main-Generator The upper left-hand corner of the operator door features a two-position auto/manual keyed switch, a generator start/stop keyed switch, and three indicator lights. Optional keyed switches may be present.

Indicator Lights The white light (Figure 6, 1) indicates the system is in Automatic mode. The blue light (Figure 6, 2) indicates the system is in Manual mode. The auto/manual keyed switch determines the operating mode.

The amber auto mode fail light (Figure 6, 3) indicates a system irregularity. The amber auto mode fail light illuminates under any of the following circumstances:

• Either drawout main circuit breaker (but not all) has been racked to the test or disconnect positions.

• Either main circuit breaker has tripped while the system was in Automatic mode for a reason (such as ground fault) that prevents transfer of source.

• A mechanical Open pushbutton has been pressed.

• The internal diagnostics have detected an error.

Exercise with Load (Optional) The optional exercise with load selector (Figure 6, 4) is a two-position keyed switch that determines whether the generator exercise will occur with or without load.

Auto/Manual Keyed Switch The auto/manual keyed switch (Figure 6, 5) has two positions. Turn the key to:

• “Auto” for automatic operation.

• “Man” (manual) to use the pushbuttons on the operator door to control the system manually.

Generator Start/Stop A generator start/stop switch (Figure 6, 6) may be used to start the generator when the auto/manual switch is set to manual mode. The switch has two positions, Stop and Start. In Manual mode, turn to the Start position to send a start signal to the generator. Turn to the Stop position to shut the generator down. In Auto mode, the generator start/stop switch is ignored.

Figure 6: Operating Mode Group: Main-Generator

1. White Automatic Indicator Light

2. Blue Manual Indicator Light

3. Amber Auto Mode Fail Light

4. Exercise with Load Switch (Optional)

5. Auto/Manual Keyed Switch

6. Generator Start/Stop Switch

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Source and UPS Status Group The source and UPS status group, located in the upper right-hand section of the operator door, features a three-position keyed switch and three lights. Another keyed switch, an illuminated pushbutton, and/or an indicator light may also be present. See Figure 7.

Indicator Lights Each white “Left Source” or “Right Source” light (Figure 7, 1) illuminates when the corresponding source is available. The red “CHK UPS OR PLC BATT” light (Figure 7, 2) indicates that either the PLC or UPS battery needs service. The “Sources Synched” light (Figure 7, 3) is supplied only on closed transition applications. When the two sources are sufficiently similar in phase angle, magnitude, and frequency, this light illuminates indicating synchronization.

Test Transfer Switch The keyed test transfer switch (Figure 7, 4) has three positions:

• TTL (Test Transfer Left)—Simulates a left source power loss causing a transfer to the right source. During proper operation, the left source light is off and the right source light is on.

• TTR (Test Transfer Right)—Simulates a right source power loss causing a transfer to the left source. During proper operation, the right source light is off and the left source light is on.

• Normal—Standard operating mode. The switch is in the Normal position when NOT simulating a source power loss.

Push-To-Test Button (Optional) The optional push-to-test button (Figure 7, 5 (not shown)) tests the condition of the indicator lights, including illuminated pushbuttons. Press the button labeled “Push-To-Test.” Check all bulbs that do not illuminate. Replace bulbs as needed.

Figure 7: Source and UPS Status Group

1. White Source Light

2. Red CHK UPS OR PLC BATT light

3. Sources Synchronized Light (Optional)

4. Test Transfer Switch

5. Push-to-Test Button (Optional); Location of button shown for reference only

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The key can only be removed when it is in the Normal position.



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Circuit Breaker Control and Status Group The circuit breaker control and status group, located on the lower half of the operator door, features a light and two illuminated push buttons for each circuit breaker.

Indicator Lights The amber “Fault” indicator light (Figure 8, 1) illuminates when the circuit breaker trips as a result of a fault condition (e.g., long time, short time, instantaneous, or ground fault).

Pushbuttons Each circuit breaker has two illuminated pushbuttons: the green open light (Figure 8, 2) and the red closed light (Figure 8, 3). In Manual mode, use these buttons to open or close the circuit breaker to which they correspond. In Automatic mode, the “Open” and “Close” pushbuttons will not control the circuit breakers. The left source group is on the bottom left; the right source group is on the bottom right.

Control Power and Power Monitor Assembly

Each utility or generator source provides power to the control power system through a 1000 volt-ampere control power transformer. The disconnecting means for control power and the power quality monitor is located within each main circuit breaker instrument compartment.

Control Power Subassembly The control power transformer (CPT) connects to source (line) side bussing of the main circuit breaker. To provide control power, the CPT transforms the line voltage to 120 volts or, if the system is already 120 volts, isolates the control circuit.

Power Quality Monitor Subassembly Each power quality monitor constantly evaluates the line voltage for an under-voltage, phase imbalance, phase loss, or phase reversal condition. When the power quality monitor senses an abnormal condition, a voltage input alerts the PLC.

Figure 8: Circuit Breaker Control and Status Group

1. Amber Fault Indicator Light

2. Green Open Illuminated Pushbutton

3. Red Closed Illuminated Pushbutton

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Generator Relay Subassembly This subassembly is present only when one of the main circuit breakers is connected to a generator instead of a utility source. The subassembly contains an overvoltage relay (Figure 9, 1) and an over/under frequency relay (Figure 9, 2). The relays’ outputs are in series with the power quality monitor’s outputs and indicate to the PLC that the generator source is available for use. The relays’ settings are adjustable. Refer to the relay manuals for details.

Sync-Check Relay Assembly The sync-check relay assembly is located in a main circuit breaker section if the automatic transfer switch is a closed transition system. The sync-check relay is shown in Figure 10. It compares “A” phase voltages from each source, and closes a contact when both are sufficiently similar in phase angle, magnitude, and frequency. The closed contact provides a voltage input to the PLC to indicate that the power sources are “in phase”. The sync-check relay is located in one section only.

Figure 9: Generator Relay Subassembly

1. Overvoltage Relay

2. Over/Under Frequency Relay1

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Figure 10: Sync-Check Relay Assembly



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UPS Assembly The uninterruptible power supply (UPS) assembly consists of three main parts: the UPS, UPS bypass relay, and the control power source contactor. Power flows from one control power subassembly through the control power source contactor, then through the UPS, and out to the control system.

Control Power Source Contactor The line side of each main circuit breaker provides power to the control power transformers. The control power source contactor directs power to the UPS from an available utility or generator source. When two sources are available, either source may be the control power source. Mechanical interlocking of the contactor keeps the sources from paralleling through the control power circuit.

UPS Bypass Relay The UPS bypass relay activates automatically to bypass the UPS to maintain the power flow to the control power system when the UPS is not functioning properly.

Figure 11: UPS Assembly

Figure 12: Control Power Source Contactor

Control power source contactors

Figure 13: UPS Bypass Relay

UPS bypass relay



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UPS Unit During normal operation, control power goes through the UPS, which acts as a voltage regulator for the control circuit. When neither the normal nor the alternate source are available, the UPS provides control power from its battery for a limited time. The UPS owner’s manual provides details about its load capability.

The UPS battery will eventually require service. The “CHK UPS OR PLC BATT” light on the operator door will indicate when one of the batteries needs service. The “Low Batt” LED on the UPS will also illuminate when the UPS battery becomes inoperative. The “Low Batt” LED on the PLC will illuminate when the PLC battery needs to be replaced.

Programmable Logic Controller (PLC) assembly

The programmable logic controller assembly is located behind the operator door and contains the PLC central processing unit (CPU), PLC power supply, and input/output (I/O) modules. The interposing relays and some terminal blocks are located here, as well. See Figure 15.

Figure 14: UPS Unit

UPS unit

Figure 15: PLC Assembly



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Disconnects and Fuses The control power disconnects (Figure 16, 1) for the transfer switch system have over amped fusing (Figure 16, 2) to provide short circuit protection only per UL® 1008 Section 19.25. DO NOT replace these fuses with lower ampere rating.

Interposing Relays The PLC outputs use Square D® Type R interposing relays to open circuit breakers and to give an optional remote status contact. See Figure 17. These relays are also used as part of an electrical interlock circuit which activates when the PLC is offline for any reason.

The DIN-rail mounted fuse blocks, (Figure 17, 3) used throughout the control power system, contain slugs and are used for troubleshooting the control system. DO NOT replace these slugs with fuses.

Figure 16: Disconnects and Fuses

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Figure 17: Interposing Relays

Interposing relays

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Remote Status Relay Subassembly This is an interposing relay on the PLC pan that closes a set of contacts when the PLC falls out of Automatic mode and enters Automatic-Fail mode. See Figure 18. The relay is wired to terminal blocks on the UPS assembly for customer connection points. Spare contacts, both normally open and normally closed, are provided at the relay.

Generator Start Relay The generator start relay is an off-delay timer relay. See Figure 19. The relay is normally energized by an output from the PLC. When the generator source is required, the PLC output goes low to de-energize the relay and close the generator start contact. In the event of total loss of control power (or if power to the PLC is disconnected), the relay will revert to its de-energized state to send a generator start signal via the same start contact.

Figure 18: Remote status relay

Remote status relay

Figure 19: Generator Start Relay



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Touch Screen Control Option

General Information The PLC control scheme can be equipped with an optional touch screen that replaces most of the door-mounted mechanical operators. The touch screen is available for the main-main and main-generator configurations. The auto/manual mode switch and generator start switch hardware will remain on the switchboard/switchgear to allow for manual control in the event that the touch screen does not work. These operators will allow the PLC to be switched to manual mode for generator starting and circuit breaker control via pushbuttons on the circuit breaker faceplates.

The touch screen provides the following features:

1. Personnel can set password-protected time delays from the touch screen. There will be no requirement for laptop computers, complicated online PLC program changes, specialized software, or cables.

2. Alarm conditions will contain specific information instead of being limited to a general summary alarm.

3. Optional event logging with time and date stamp is available. This feature allows personnel to track when and why transfers occurred.

4. Two levels of password protection are available to limit personnel access. This will ensure that only authorized personnel can access control buttons and switches for transfer operations. A second level of password protection will allow adjustment of time delays and password administration.

5. The display is backlit, which allows for manual operation in low ambient light conditions.

Touch Screens The touch screens available are:

• Main

• Settings

• Programmable Logic Controller Input/Output (PLC I/O) Map

• Sequence of Operation

• Alarm Log (optional)

• Event Log (optional)

Main Screen The main screen contains system status indicators, circuit breaker control buttons, system control switches, password access button, date and time display, and screen access buttons. See Figure 20.

The screen pictures on pages 20–22 are typical for main-main and main-generator applications.

Figure 20: Main Screen



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Settings Screen The settings screen contains touchpads for changing delay and timer settings, time and date settings, access to touch screen system configuration, and password administration. See Figure 21.

PLC I/O Map The PLC contains input/output (I/O) lists with indicators for status. See Figure 22.

Alarm Log (Optional) The alarm log contains a running list of alarms generated by system events (i.e., circuit breaker faults, circuit breaker connection status, auto fail mode, etc.). See Figure 23.

Figure 21: Settings Screen

Figure 22: PLC I/O Map Screen

Figure 23: Alarm Log Screen



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Event Log (Optional) The event log contains a running list of system events (i.e., switch activation, circuit breaker status, etc.). See Figure 24.

Press the X in the lower right corner of the touch screen to close that window and allow visibility of all functions.

Password Access The main screen displays the image of a closed padlock in the lower left corner. See Figure 25.

1. Touch the padlock image to call up a touchpad for numeric data entry.

2. Enter the level 1 password (default 1234) to unlock access to the control switches and pushbuttons.

3. Use the required level 2 password (default 4321) to unlock the settings screen and to allow all level 1 functionality.

4. Touch the enter key to return to the main screen after entering the appropriate password.

If the correct password was entered, the screen will display an unlocked padlock image with the active password level of 1 or 2.

5. Touch the push-to-lock touch pad to re-locked the system at any time.

When power is turned on, the touch screen will be illuminated before the PLC goes into “run mode” for about 10 sec.

Figure 24: Event Log Screen

Figure 25: Password Access



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The password access mode will eventually time out and automatically re-lock (as indicated by a return to the locked padlock image). The duration of the password security timer can be adjusted on the settings screen. Passwords also can be changed on this screen.

1. Call up the settings screen, and a new button appears which allows a password override.

2. Touch the password override button to call up a screen that allows both the level 1 and level 2 passwords to be viewed and/or reset.

Control Operation Enter the level 1 password to access control switches and pushbuttons on the main screen. Simply touch a pushbutton to activate it. To change a switch position, touch the switch. A popup window appears presenting additional touchpads for each switch position. Touch the desired switch position which closes the popup window and activates the switch. Help screens are available for each switch. Access the help screen by touching the “?” touch pad on the switch popup screen. Popup screens can be closed by touching the red “X” in the upper right corner, touching the desired function or touching an “OK” button.

Control Settings 1. Enter the level 2 password to access the settings screen.

2. Touch a time value to enter a new value on a popup numeric keypad.

3. Access help screens by touching the “?” touch pads near the setting in question.

4. Access time and date settings by touching the “PLC Time Set” or “PLC Date Set” button.

5. Adjust time and date settings by touching the up or down arrows that appear above and below the desired value.

Alarm and Event Logs (Optional) Enter the level 1 password to view these screens if supplied.

Events appear on a summary list with the most recent occurrences near the top.

Active events/alarms are displayed as red, acknowledged items appear yellow, and events/alarms that have returned to normal are displayed as green.

If the password(s) is forgotten, a “back-door” access password (32767) can be entered for level 2 access.

The auto/manual mode switch and generator start switch are not located on the touch screen, but are on the equipment next to the touch screen.

The touch screen has its own date/time function that will not control the PLC date/time. Consult the touch screen instructions for other functions not covered here, such as backlighting levels.

Pressing the “acknowledge all events” button will change event status from red to yellow.



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Mechanical Interlocking Cable Assembly

Open Transition A cable assembly provides mechanical interlocking between the two main circuit breakers used in the automatic transfer switch to prevent closed transition. Both circuit breakers may be open, but only one may be closed at a time. Refer to the Mechanical Interlocking Kit instruction bulletin for installation and calibration instructions, if these cables were not factory installed.

closed transition There is no mechanical interlocking between the two main circuit breakers for closed transition switch systems.

Operation

Main-Main System This section describes the Automatic operation mode of the automatic transfer switch scheme provided for a main-main or “two utility” system. Either the left or right main circuit breaker can be the normal or emergency source.

Initial (Default) Setting The default setting is one main circuit breaker (designated “normal”) closed and one main circuit breaker (designated “alternate”) open. The left circuit breaker is the “normal” circuit breaker unless otherwise specified, either when initially ordered or by the PSS position.

Normal Source Lost If the normal source is lost, the PLC automatically transfers the load to the alternate source. The normal circuit breaker opens after the open delay. After the close delay, the alternate circuit breaker closes.

Normal Source Returns—PSS Off/ No PSS Option

Without the PSS option, or if the PSS is Off, the system will remain in the transferred state, even after the normal source returns. The alternate circuit breaker will remain closed until manual intervention (or the alternate source is lost), allowing the user to schedule retransfer at a convenient time.

Normal Source Returns—PSS On If the PSS is On,

• In an open-transition system, after the source stabilization delay, the alternate circuit breaker opens. After the close delay, the normal source closes.

• In a closed transition system, after the source stabilization delay, if the sync-check relay is satisfied, the normal circuit breaker closes. Two seconds later, the alternate circuit breaker opens. If the sync-check relay is not satisfied, retransfer will be delayed until the sources are synchronized.

Alternate Source Lost If the alternate source is lost while the normal source is out, the alternate source circuit breaker will open. The breaker associated with the first returning source will close after the source stabilization delay.

Auto Retransfer (Optional) If equipped with the auto retransfer switch:

• With the switch in the Off position, the user controls the transfer manually.

• With the switch in the On position, the transfer will occur automatically.

Main-Generator System This section describes the Automatic operation mode of the automatic throwover scheme for a system with one connection to a utility source and another to a generator.



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Initial (Default) Setting Under normal circumstances, the main circuit breaker connected to the utility is closed and the main circuit breaker attached to the generator is open. Unless otherwise specified, the utility source is the left circuit breaker and the generator breaker is on the right.

Normal Source Lost The system automatically transfers the load to the alternate source. The Normal circuit breaker opens after the Open Delay, and the start signal goes out to the generator. The alternate circuit breaker closes 10 seconds after the automatic throwover system’s generator relays are satisfied, indicating both voltage and frequency are within desirable limits.

Normal Source Returns—Open Transition

After the source stabilization delay has expired, the system will retransfer to the normal source in an open transition sequence. First, the generator circuit breaker opens. After the close time delay, the normal circuit breaker will close. The generator will run in an unloaded state for 15 minutes to allow for cool-down.

Normal Source Returns—closed transition

After the source stabilization delay has expired, the system will retransfer to the normal source in a closed transition sequence. If the sync-check relay is satisfied, the normal circuit breaker closes, and after two seconds the generator circuit breaker opens. The generator will run in an unloaded state for 15 minutes to allow for cool-down. If the sources are not synchronized, retransfer will be delayed until the sources are synchronized.

Generator Source Lost While Normal Source Is Out

If the alternate (generator) source is lost while the normal source is out, the alternate source circuit breaker will open. The circuit breaker associated with the first returning source will close after the source stabilization delay.

Exercise Period Every Sunday at 1:00 p.m., a start signal will be sent to the generator for 30 minutes. The exercise period may be loaded or unloaded if equipped with the optional exercise with load selector switch. If exercise with load is selected, a transfer to the generator source will occur during the exercise period.

Conditions That Prevent Transfer of Source

Downstream Fault If a main circuit breaker trips as a result of a downstream fault, electrical interlocking does not allow either device to close. In Manual mode, the Close pushbuttons are locked out. In Automatic mode, closure is not allowed. A tripped circuit breaker also activates the amber “Auto Fail” light. Automatic transfer does not occur until the fault is cleared and the circuit breaker is reset. Refer to the circuit breaker literature for instructions on how to reset the auxiliary contacts. To reset the automatic transfer switch, turn the “auto/manual” switch to Manual and back to Auto.

Other Conditions Phase imbalance, phase reversal, or source voltage that exceeds limits (including total loss of voltage) will de-energize the power quality monitor, not allowing the associated main circuit breaker to close. A generator source is also monitored for overvoltage and proper frequency.

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Installation

Preparation for Receiving Equipment

The automatic transfer switch is contained in several switchboard or switchgear sections. See the switchboard or switchgear manual for general information pertinent to the equipment sections.

The Modicon® PLC has environmental restrictions different from that of the equipment as a whole. These restrictions can be found in the Modicon PLC User’s Guide. Be sure to store and install the equipment in accordance with the tighter restrictions. For example, if the Modicon central processing unit (CPU) has temperature limits of 32–140 °F (0–60 °C ), and the equipment has limits of 32–167 °F (0–75 °C), then keep the equipment between 32–140 °F (0– 60 °C).

Location and Interconnection of Assemblies

The parts of the automatic transfer switch are distributed among several switchboard or switchgear sections and must be wired together. Refer to the factory-supplied drawings shipped with the equipment for exact locations and subassembly interconnections.

Final Wiring Connections As previously noted, the parts of the automatic transfer switch system are distributed among several equipment sections and must be wired together. Some terminal blocks may be near the bottom of the front or rear corner channels. Refer to the wiring diagrams furnished with the switchboard or switchgear to confirm all wiring connections.

Installing the Equipment 1. For a generator system, connect the external wiring on terminal blocks GEN 1 and GEN 2. The wiring must be run in conduit.

2. For remote status indication, connect the external wiring on terminal blocks AL 1 and AL 2 on the UPS assembly.

3. Complete all wiring between the sections for the control power and signals. The terminal blocks are typically located at the bottom of the front or rear corner channels of each section.

Checkout Before Energizing The control power system has two or more disconnects.

1. Use the mechanical Open button on each circuit breaker to open the mains.

2. Turn the “auto/manual” switch on the operator door to the Manual position.

3. Turn all load (distribution) devices off.

4. Turn all control power disconnects to the On position.

5. Close and secure all covers and doors.

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Performance Checkout

Follow the checkout procedures in the “Installation” and “Maintenance” documentation for the equipment.

1. Energize the equipment.

2. Turn on the uninterruptible power supply (UPS) that is supplied with the equipment.

3. Complete the appropriate test of the Manual mode as described for the installed system in the “Test Procedures” section of this bulletin, beginning on page 28.

4. Complete the appropriate test of the Automatic mode as described for the installed system in the “Test Procedures” section of this bulletin, beginning on .

5. Complete any steps for installed devices, including circuit breaker tests, ground fault tests, or metering circuit checkout as described in the appropriate documentation.

Placing Into Service Place the automatic transfer switch system into service after satisfactory completion of the “Performance Checkout” on page 27 and all outlined tests.

1. Open or close the main circuit breakers to the desired initial condition using the automatic transfer switch operator door switches.

2. Position all switches on the operator door to the desired positions.

3. Remove the keys from the keyed switches, and store in a secure but accessible location.




• The control circuit and bus work are energized during the performance tests. Thoroughly review the equipment drawings, documentation, and design before starting any performance testing.




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Test Procedures Before beginning any test procedure, complete the installation steps outlined in “Checkout Before Energizing” on page 26. Identify the system type (main-main or main-generator), and whether the system has options (PSS or closed transfer), to select correct test procedure set. Complete the tests as outlined in “Performance Checkout” on page 27.

Perform the appropriate tests for Manual and Automatic modes quarterly. Record test dates and results in the “Maintenance Log” on page 40.

Additionally, this bulletin describes a standard sequence of operation for the switch. The standard sequence follows one of the “Operation” sections beginning on page 24 of this manual. The switch is checked for proper sequence using one of the “Test Procedures” in the “Installation” section of this bulletin. Any changes to the standard sequence are documented in separate instructional materials that are provided by the factory.

Main-Main Base System This section covers testing recommended for a two-utility system when no options are installed.

Manual Mode With the switch in Manual mode, an operator can open and close each circuit breaker independently using the pushbuttons on the operator door. Only one main circuit breaker may be closed at a time, avoiding closed transition. A two-second delay occurs between opening one main and closing the other.

This bulletin is for use by installers and specifiers and describes standard switches. For installations that deviate from these standards, this bulletin provides basic information only. Standard systems always include a uninterruptible power source (UPS). Options available are a PSS switch, exercise with load, auto-retransfer and, push-to-test pushbuttons. Refer to the documentation supplied by the factory for any deviations to the standard system.

Table 1: Manual Mode Test Procedures for Basic Main-Main

1. Complete the following:

Turn the auto/manual switch to the Manual position.

Open both main circuit breakers with the mechanical Open button located on the circuit breakers.

Turn the TTL/Normal/TTR switch to the Normal position.

2. Verify that the following lights are on:

White Left Source light

White Right Source light

Green Left Main Open light

Green Right Main Open light

Blue Manual Mode light

3. Verify that the following lights are off:

Amber Left Main Fault light

Amber Right Main Fault light

White Auto Mode light

4. Press the red Left Main Close pushbutton on the operator door.

Green Left Main Open light will turn off

Red Left Main Closed light will turn on

5. Open the left main circuit breaker using the green Open pushbutton on the operator door.

Red Left Main Closed light will turn off

Green Left Main Open light will turn on

6. After two seconds, press the red Right Main Close pushbutton on the operator door.

Green Right Main Open light will turn off

Red Right Main Closed light will turn on

7.Open the right main circuit breaker using the green Open pushbutton on the operator door.

Red Right Main Closed light will turn off

Green Right Main Open light will turn on

NOTE: If the pushbutton to close one main circuit breaker is pressed while the other main circuit breaker is closed, the input is ignored.



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Automatic Mode The operator door pushbuttons will not operate the circuit breakers in Automatic mode.

Table 2: Automatic Mode Test Procedures for Basic Main-Main





2. Verify the following lights are off:

Amber Auto Fail light



3. Verify the following lights are on:




4. Turn the auto/manual switch to Auto. Normal source main circuit breaker will close


White Auto light

Red Normal Closed light

Green Alternate Open light





7.Simulate a loss of the normal source by turning the TTL/Normal/TTR switch to TTL (Test Transfer Left) or TTR (Test Transfer Right), whichever is the normal source. The normal main circuit breaker will open after the Open Delay. The Close Delay begins timing once the normal circuit breaker opens. After the Close Delay has timed out, the alternate source main circuit breaker will close.

8.Verify the following lights are on:

Green Normal Open light

Red Alternate Closed light

White Alternate Source light

NOTE: The light for the normal source will be off.

9. Simulate normal source voltage return by turning the TTL/Normal/TTR switch back to the Normal position. The alternate main circuit breaker will continue to power the load, but the normal source light will be on.

10.Simulate a loss of the alternate source by turning the TTL/Normal/TTR switch to TTL (Test Transfer Left) or TTR (Test Transfer Right), whichever is the alternate source. The alternate main circuit breaker will open after the Open Delay. The Close Delay begins timing once the alternate circuit breaker opens. After the close delay has timed out, the normal source main circuit breaker will close.


Green alternate Open light

Red normal Closed light

White normal Source light

NOTE: The source light for the alternate source will be off.

12. Simulate alternate source voltage return by turning the TTL/Normal/TTR switch back to the Normal position. The normal main circuit breaker will continue to power the load, but the alternate source light will be on.



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Main-Main Standard Options This section covers testing recommended for a main-main system with standard options. These options include PSS and auto-retransfer.

Manual Mode With the switch in Manual mode, an operator can open and close each circuit breaker independently using the pushbuttons on the operator door. The PSS does not impact Manual mode.

Table 3: Manual Mode Test Procedures for Main-Main with Options





Turn the PSS switch to the Off position.




Green Left Main Open light

Green Right Main Open light






4. Press the red Left Main Close pushbutton on the operator door.



5.

Move the PSS switch to the right position (prefer right source)

Press the Right Main Close pushbutton on the operator door. In a closed transition system with a satisfied sync-check relay.

Green Right Main Open light will turn off

Red Right Main Closed light will turn on

After two seconds, the left main circuit breaker will open. The indicating lights for the left circuit breaker will change status.

NOTE: If the synchronizing relay is not satisfied or is not installed, the command to close the right main will be ignored. Likewise, if the closed transition selector switch is in the Off position, the command to close the right main will be ignored.

6.

Move the PSS switch to the left position (prefer left source)

Press the Left Main Close pushbutton on the operator door. In a closed transition system with a satisfied sync-check relay.



After two seconds, the right main circuit breaker will open. The indicating lights for the right circuit breaker will change status.

NOTE: If the synchronizing relay is not satisfied or is not installed, the command to close the left main will be ignored.



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Automatic Mode The operator door pushbuttons will not operate the circuit breakers in Automatic mode.

Table 4: Automatic Mode Test Procedures for Main-Main with Options





Turn the PSS switch to the Off position.

Turn the Auto Retransfer Selector switch to the On position.









4. Turn the auto/manual switch to Auto. The normal source main circuit breaker will close.


White Auto light








7.Simulate a loss of the utility source by turning the TTL/Normal/TTR switch to TTL (Test Transfer Left) or TTR (Test Transfer Right), whichever is the normal source. The normal main circuit breaker will open after the Open Delay. The Close Delay begins timing once the normal circuit breaker opens. After the Close Delay has timed out, the alternate main will close.





NOTE: The source light for the normal source will be off.

9.

Simulate normal source voltage return by turning the TTL/Normal/TTR switch back to the Normal position.

With PSS and open transition, the system may retransfer to the normal circuit breaker. To allow the retransfer, set the PSS to the normal source position. To avoid retransfer, set the selector switch to the center/Off position. With the PSS set to the normal source position, the source stabilization delay begins timing once the normal source returns. After timing out, the alternate circuit breaker opens. After the Close Delay, the normal circuit breaker closes.

With PSS and closed transition, the source stabilization timer begins to time out once the normal voltage returns. With the PSS set to the normal source position, the normal circuit breaker closes. Two seconds later, the alternate circuit breaker opens.

NOTE: Without the PSS, the system does not retransfer. If the Auto Retransfer switch is set to the Off position, retransfer will be suspended until it is moved to the On position.

10. To simulate a loss of the utility alternate source, have the system set as follows:

Normal Main open

Alternate Main closed

PSS, if present, off

both Source lights on

11. Simulate loss of alternate source by turning the TTL/Normal/TTR switch to the alternate source. The alternate circuit breaker will open after the Open Delay, and after the Close Delay the normal circuit breaker will close.

12. Simulate alternate source voltage return by turning the TTL/Normal/TTR switch back to the Normal position. The normal main circuit breaker will continue to power the load.



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Main-Generator Base System This section covers testing recommended for a utility-generator system with no options. The normal circuit breaker connects to the utility source, and the alternate circuit breaker connects to the generator.

Manual Mode With the switch in Manual mode, an operator can open and close each circuit breaker independently using the pushbuttons on the operator door. Only one main circuit breaker may be closed at a time, avoiding closed transition. A two-second delay occurs between opening one main and closing the other.

Table 5: Manual Mode Test Procedures for Basic Main-Generator





Turn the Generator Start switch to the Stop position.


White normal Source light

Green normal Main Open light

Green alternate Main Open light



White alternate Source light

Amber normal Main Fault light

Amber alternate Main Fault light


4. Start the generator by turning the Generator Start switch to the Start position. Proceed with this test when the source available light for the generator is on.

5. Press the red Normal Main Close pushbutton on the operator door.

Green Normal Main Open light will turn off

Red Normal Main Closed light will turn on

6. Open the Normal main circuit breaker using the green Open pushbutton on the operator door.

Red Normal Main Closed light will turn off

Green Normal Main Open light will turn on

7. After two seconds, press the red Alternate Main Close pushbutton on the operator door.

Green Alternate Main Open light will turn off

Red Alternate Main Closed light will turn on

8. Open the Alternate main circuit breaker using the green Open pushbutton on the operator door.

Red Alternate Main Closed light will turn off

Green Alternate Main Open light will turn on

9.Turn the Generator Start switch to the Stop position. Generator will continue to run until the cool-down period has expired.

NOTE: If the Normal Main Close pushbutton is depressed while the Generator (Alternate Main) Breaker is closed and the sync-check relay conditions are satisfied, a transfer to the Utility (Normal Main) Source will occur, since it is preferred by default.



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Automatic Mode The operator door pushbuttons will not operate the circuit breakers in Automatic mode. The position of the Generator Start switch does not affect operation of the PLC system while in Automatic mode.

Table 6: Automatic Mode Test Procedures for Basic Main-Generator







White Normal Source light

Green Normal Main Open light

Green Alternate Main Open light




Amber Normal Main Fault light

Amber Alternate Main Fault light


4. Turn the auto/manual switch to Auto. The normal main circuit breaker will close.


White Auto light








7.Simulate a loss of the normal source by turning the TTL/Normal/TTR switch to TTL (Test Transfer Left) or TTR (Test Transfer Right), whichever is the normal source. The normal main circuit breaker will open after the Open Delay. The start signal will be sent to the generator. After the generator source has stabilized, the generator circuit breaker will close.





NOTE: The white normal Source light will be off

9.Simulate normal source voltage return by turning the TTL/Normal/TTR switch back to the Normal position. Retransfer to the utility source will occur. After the stabilization delay, the generator circuit breaker will open. After the Close Delay, the normal circuit breaker will close and the generator will continue to run until the cool-down period has expired.



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Main-Generator Standard Options This section covers testing recommended for a main-generator system with standard options. These options include having closed transition and exercise with load.

Manual Mode With the switch in Manual mode, an operator can open and close each circuit breaker independently using the pushbuttons on the operator door.

Table 7: Manual Mode Test Procedures for Main-Generator with Options
















4. Start the generator by turning the Generator Start switch to the Start position. Proceed with this test when the source available light for the generator is on.

5. Press the red Normal Main Close pushbutton on the operator door.



6.

Press the Alternate Main Close pushbutton on the operator door. In a closed transition system with a satisfied sync-check relay:

Green Alternate Main Open light will turn off

Red Alternate Main Closed light will turn on

After two seconds, the normal main circuit breaker will open. The indicating lights for the normal circuit breaker will change status.

NOTE: If the synchronizing relay is not satisfied or is not installed, the command to close the alternate main breaker will be ignored.

7.

Press the Normal Main Close pushbutton on the operator door. In a closed transition system with a satisfied sync-check relay:



After two seconds, the alternate main circuit breaker will open. The indicating lights for the alternate circuit breaker will change status.

NOTE: If the synchronizing relay is not satisfied or is not installed, the command to close the normal main breaker will be ignored.

8. Turn the Generator Start switch to the Stop position. Generator will continue to run until the cool-down period has expired.



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Automatic Mode The operator door pushbuttons will not operate the circuit breakers in Automatic mode. The position of the Generator Start switch does not affect operation of the PLC system while in Automatic mode.

Table 8: Automatic Mode Test Procedures for Main-Generator with Options
















4. Turn the auto/manual switch to Auto. The normal source main circuit breaker will close.


White Auto light








7.Simulate a loss of the utility source by turning the TTL/Normal/TTR switch to TTL (Test Transfer Left) or TTR (Test Transfer Right), whichever is the normal source. The normal main circuit breaker will open after the Open Delay.

The start signal will be sent to the generator. After the generator source has stabilized, the generator circuit breaker will close.





NOTE: The white Normal Source light will be off.

9.

Simulate normal source voltage return by turning the TTL/Normal/TTR switch back to the Normal position. Retransfer to the utility source will occur after the stabilization delay has expired for the utility source.

With open transition, the generator circuit breaker opens. After the Close Delay, the normal circuit breaker closes.

With closed transition, the normal circuit breaker closes. Two seconds later, the generator circuit breaker opens.

The generator will continue to run until the cool-down period has expired.

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Troubleshooting and Maintenance

Changing Fuses Turn off the control power disconnect switch before removing fuses. The control power disconnects for the transfer switch system have over-amped fuse ratings to provide short-circuit protection only. Do Not replace these fuses with a lower amperage rating. The DIN-rail mounted fuse blocks used throughout the control power system contain slugs, not fuses. Do Not replace these slugs with fuses. These fuse blocks are fed power from multiple sources. Use a properly rated voltage sensing device to confirm that power is off.

Checking Light Bulbs

With Push-To-Test Option 1. Press the Push-To-Test pushbutton. All of the bulbs on the operator door should illuminate.

2. Replace any bulbs that do not illuminate.

With No Push-To-Test Option All lights are long-life, protected LEDs. If a light does not illuminate, replace it with one of the same type.




• Disconnect all sources of electric power before beginning visual inspections, tests, or maintenance.

• Assume all circuits are live until completely deenergized, tested, grounded, and tagged.

• Use a properly rated voltage sensing device to confirm that the power is off.

• Check all power sources, including possible backfeeding.

Failure to follow these precautions will result in death, severe personal injury, or equipment damage.

80332-001-03 Automatic Transfer Switch: Model ATS-NW07/2007 Troubleshooting and Maintenance


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Troubleshooting Chart All work should be completed by qualified electrical personnel.




• Turn off all power supplying this equipment before working on or inside equipment.

• Always use a properly rated voltage sensing device to confirm power is off.

• Check all power sources, including possible backfeeding.


Table 9: Troubleshooting

Condition Possible Cause Suggested Action

CHK UPS OR PLC BATT light onPLC battery low If the battery light on the front of the PLC is lit, follow instructions in the Modicon

PLC User's Guide to change the battery in the PLC.

UPS battery low Check the UPS status indicators to determine if the UPS battery has caused the alarm.

Red or Green circuit breaker status light not on Light bulb inoperative Check light bulb, replace as necessary. (Use Push-to-Test button when available.)

White source light not on, but source is available

Light bulb inoperative Check light bulb, replace as necessary. (Use Push-to-Test button when available.)

TTL/Normal/TTR switch not in Normal position Return the switch to the normal position.

Power quality monitors not satisfied Refer to other meters or voltage monitors to determine if voltage is within the limits of the voltage and frequency relays, including proper phase rotation.

Normal source lost, but transfer did not occur

Main circuit breaker tripped because of fault

The trip indicator on each circuit breaker will note the type of fault that occurred. Identify and correct cause of overload or fault. Reset circuit breaker.

System not in Automatic mode Verify the auto/manual switch is turned to Auto, and white Auto light is on.

Alternate not available System will not transfer to an unavailable source. Check utility availability or generator functionality.

Amber Auto Fail light is on

Mechanical open or close button was depressed

Turn the auto/manual switch to Manual and then to Auto to reset system.

NOTE: Circuit breakers may change state to return to normal status.

Circuit breaker racked outSystem will remain inoperative until all main circuit breakers are in the same position, either connected or test. Turn the auto/manual switch to Manual and back to Auto to reset.

Main circuit breaker trippedIdentify and correct cause of overload or fault. Reset circuit breaker. Turn the auto/manual switch to Manual and back to Auto to reset system from Auto mode fail.

PLC has determined an error in the PLC internal program

An error internal to the PLC CPU will be indicated by the LED on the CPU. See the Modicon® PLC User's Guide for more information.

Source transferred “without reason” Temporary voltage loss or sagIf recording voltage meters are not installed, consult with the utility to find out if a momentary outage occurred. A voltage dip below the set point of the power monitor may result in transfer operation.

Generator did not start

Signal not sentGo through manual test. Watch for the PLC output light 6 on Output Module 1. It should normally be illuminated and will go out when the generator start command should be sent. If it does not go out, contact Square D Field Services.

Signal not received Verify wiring connections between the time delay relay and the generator set.

Signal received, generator would not start Refer to the generator system documentation.

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List of Standard Values and Arrangements

This list contains the standard factory installed settings, including programmed options. If these values do not apply to your equipment, note those differences in this bulletin.

All Systems

Generator Systems

Table 10: System Settings

Open Delay3 seconds. Timing begins after power quality monitor deenergizes.

Close Delay 2 seconds. Timing begins after a circuit breaker opens.

Transfer Delay—Open Transition Open delay plus close delay.

Transfer Delay—closed transition2 seconds maximum when sourcesare synchronized

Sync-Check Relay1

1 Settings are field adjustable.

10–30% nominal voltage

6–20% phase angle

NOTE: Both voltage and phase angle are changed by one potentiometer.

Source Stabilization Timer 10 seconds to retransfer to Preferred Source.

Power Quality Monitor115% undervoltage (fixed)

5–15% phase imbalance

0–10 second time delay

Table 11: System Configuration

System Normal Source Alternate Source

Main-Main, Main-Generator Left main circuit breaker Right main circuit breaker

Table 12: Generator System Settings

81 Relay1

1 Settings are field adjustable.

50–70 Hz over-frequency.1–3 Hz differential

50-70 Hz under-frequency.1–3 Hz differential

59 Relay1 100–125% over-voltage1–15% differential

Generator Options (not field adjustable, except with optional touch screen)

Cool-down period: 15 minutes (unloaded)

Exercise period: 30 minutes per week (loaded or unloaded) Will start Sunday at 1 p.m.

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Connection to Circuit Breakers

Connection to Circuit Breakers Factory-installed wiring to circuit breakers includes open and close coils, circuit breaker status contacts, and fault-indicating contacts, along with other specified accessories. For field changes, refer to the appropriate circuit breaker manual. For information specific to each of the circuit breakers, refer to their respective instruction bulletins.

References The approval drawings show details of wiring interconnections, including installed options, unique to each automatic transfer switch installation. Schneider Electric provided one set of drawings with the equipment.

Contact Square D Services or the Customer Information Center at 1-888-SquareD (1-888-778-2733) for start-up service or general questions about a specific installation.

Most instruction bulletins and other literature can be obtained from the Online Literature Fulfillment (OLF) Center and from the Schneider Electric Technical Library at www.us.SquareD.com.

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Maintenance Log

Table 13: Maintenance Log Table

Date Description

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Table 13: Maintenance Log Table (continued)

Date Description

Electrical equipment should be installed, operated, serviced, and maintained only by qualified personnel. No responsibility is assumed by Schneider Electric for any consequences arising out of the use of this material.

80332-001-03 © 2003–2007 Schneider Electric All Rights Reserved Replaces 80332-001-02, 08/2006

8821 Garners Ferry RoadHopkins, SC 29061 USA1-888-SquareD (1-888-778-2733)www.us.SquareD.com

07/2007

Schneider Electric USA

Automatic Transfer Switch: Model ATS-NWInstruction Bulletin

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