ASCO Series 300 Automatic Transfer Switches

Important Safety Information

DANGER is used in this manual to warn of high voltages capable of causing shock, burns, or death.

WARNING is used in this manual to warn of possible personal injury.

CAUTION is used in this manual to warn of possible equipment damage.

Refer to the outline and wiring drawings provided with ASCO Series 300 ATS for all installation details.

An experienced licensed electrician must install the ATS.

ASCO POWER TECHNOLOGIES L.P.
50 Hanover Road, Florham Park, New Jersey 07932-1591 USA
Telephone: 1 800 937-2726 (ASCO), Service: 1 800 800-2726 (ASCO)
www.asco.com

ASCO POWER TECHNOLOGIES CANADA
PO Box 1238, 17 Airport Road, Brantford, Ontario, Canada N3T 5T3
Telephone: 519 758-8450, Fax: 519 758-0876, Service: 1 888 234-2726 (ASCO)
www.asco.ca

Document Number: 381333-122 C

Nameplate and Catalog Number Identification

The Transfer Switch nameplate includes data for each specific ASCO Series 300 ATS. Use the ATS only within the limits shown on this nameplate.

A typical Catalog Number is shown below with its elements explained. The example is for a G-design Series 300 ATS with switched neutral, 3 pole, 2000 amp, 480 V, in a Type 1 enclosure:

Catalog Number Structure Example: G300 3 2000 N 1 C

* Type 4 & 12 enclosures are available only for 1000, 1200, & 1600 amp sizes.

Visual Description: An image shows a large metal enclosure, identified as a 2000 amp size in a typical enclosure with customer connection points. Labels point to 'neutral connections', 'power connections', 'Transfer Switch', 'Controller', and 'membrane controls'. Another diagram shows the internal components of the transfer switch, with labels for 'terminal block TB for engine start and switch position contacts'.

Section 1: Installation

ASCO Series 300 Automatic Transfer Switches (ATSs) are Listed under Underwriters Laboratories UL 1008 Standard for Safety and CSA C22.2 No. 178 Standard for Automatic Transfer Switches. Control features are UL Component Recognized, meeting OSHA Safety Requirements.

ATSs are suitable for emergency and standby system applications, meeting requirements for NEC Article 700 (Emergency), Article 517 (Health Care), Article 701 (Legally Required Standby), Article 702 (Optional Standby), NFPA 99, and NFPA 110.

Rating Label

Each ATS has a rating label specifying load and fault circuit withstand/closing ratings. Do not exceed these values, as it can cause personal injury or equipment damage.

Shipping Skid Removal

Open the front door and remove the four lag screws (two front, two rear) securing the enclosure to the wood skid.

Supporting Foundation

The foundation must be level and straight. Refer to the applicable enclosure outline drawing for mounting details and door opening space. If bottom cable entry is used, prepare the foundation for conduit stubs, ensuring proper cable bending space and clearance to live metal parts. Use conduit spacer caps or templates for alignment.

Mounting

Mount the Series 300 according to details and instructions in the applicable enclosure outline drawing.

Auxiliary Cable Box (1000-2000 amp)

An auxiliary cable box is required if power cables do not enter directly adjacent to terminal lugs. Order ASCO part no. 609027 if needed. Do not route power cables along the sides of the Transfer Switch.

Line Connections

Refer to the Wiring Diagram. All wiring must comply with the National Electrical Code and local codes. Pole covers are not necessary to remove; if removed, reinstall carefully.

WARNING: De-energize conductors before making connections. Ensure proper phase rotation for Normal and Emergency sources. Place engine generator starting control in the OFF position.

Testing Power Conductors

Do not connect power conductors until they are tested. Pulling cables can damage insulation. Test cables after pulling to verify they are not defective.

CAUTION: Protect the ATS from construction grit and metal chips.

Connecting Power Conductors

After testing, connect power cables to the appropriate terminal lugs as shown on the wiring diagram. Use suitable lugs. Be careful when stripping insulation to avoid nicking conductors. Clean surface oxides with a wire brush. For aluminum cable, apply joint compound. Tighten lugs to the torque specified on the rating label.

Controller Ground

Connect a grounding wire to the controller's lower left mounting stud. Use a conductive strap between the enclosure and the door for proper grounding.

Harnesses

The transfer switch connects to the controller via a plug-in harness (two plugs).

Engine Starting Contacts

Customer connections for engine control and TS auxiliary contacts are on terminal block TB. Refer to the wiring diagram and connect engine start wires to appropriate terminals (See Figure 1-1 and Table A).

Figure 1-1 Description: Diagram showing connections to the engine starting contact terminal block on the Transfer Switch, indicating terminals for Engine Starting Signals and TS Auxiliary Contacts.

Auxiliary Circuits

Connect auxiliary circuit wires to transfer switch terminal block TB as shown on the wiring diagram. Refer to Section 5, Control Features for necessary auxiliary connections.

Figure 1-2 Description: Diagram of the Controller's lower terminal block, showing input/output labels for Load Disconnect Feature Connections, Programmable Engine Exerciser connection, and Remote Control Features Connections. It indicates connections for Load Disconnect Contacts, Optional Engine Exerciser, Momentary Test Switch, Maintained Open to Transfer to Emergency, Inhibit Transfer to Emergency, Bypass Transfer Time Delay, and Factory Use Only terminals.

Functional Test

Consists of three checks: manual operation, voltage checks, and electrical operation. Perform checks in the order presented.

WARNING: Do not manually operate the transfer switch until both power sources are disconnected (open both circuit breakers).

1. Manual Operation Test

A detachable maintenance handle is provided for manual operation checks before energizing.

Figure 1-3 Description: Diagram illustrating the maintenance handle, showing how to turn it counterclockwise to Emergency and clockwise to Normal, and how to insert it onto the shaft.

Figure 1-4 Description: Diagram showing contact position indicators and maintenance handle operation. It illustrates how turning the handle counterclockwise closes Emergency contacts and opens Normal contacts, while turning clockwise closes Normal contacts and opens Emergency contacts.

Procedure:

1. After de-energizing sources, open the enclosure door. Remove the maintenance handle and hub. Install the hub onto the center operator shaft and insert the handle firmly.
2. If the switch is closed on Normal, turn the handle counterclockwise. The switch should operate smoothly.
3. Turn the handle clockwise to return to the Normal position. Observe window indicators.
4. Remove and store the maintenance handle and hub.

WARNING: Verify the maintenance handle and hub have been removed before proceeding.

2. Voltage Checks

Verify that rated voltage on the nameplate matches normal and emergency line voltages. Ensure feeders are connected to the proper lugs.

DANGER: Use extreme caution when measuring voltages. Do not touch power terminals.

Procedure:

1. Close the normal source circuit breaker. Observe 'Connected To Normal' and 'Normal Source Available' lights.
2. Use a voltmeter to check phase-to-phase and phase-to-neutral voltages at the normal source terminals.
3. Close the emergency source circuit breaker (start generator if necessary). Observe 'Connected To Normal' and 'Emergency Source Available' lights.
4. Use a voltmeter to check phase-to-phase and phase-to-neutral voltages at the emergency source terminals.
5. Use a phase rotation meter to check emergency source phase rotation; it must match the normal source.
6. Shut down the engine-generator. Observe 'Emergency Source Accepted' light goes off. Set generator starting control to automatic. Close enclosure door.

Figure 1-5 Description: Diagram of standard controls and indicators, showing the 'LOAD CONNECTED TO' (Normal/Emergency) and 'SOURCE AVAILABLE' (Normal/Emergency) lights, and control buttons like 'TRANSFER SWITCH TEST', 'BYPASS TIME DELAY', 'SET ENGINE EXERCISER'.

3. Electrical Operation

Verify nameplate voltage matches line voltages and feeders are correctly connected.

DANGER: Use extreme caution when measuring voltages.

NOTE: Motor Load Transfer feature may affect transfer timing based on phase relationship.

Procedure:

1. Ensure normal source is available and generator is ready. Check 'Normal Source Available' light.
2. Press and hold the 'Transfer Switch Test' button until the engine starts and runs (within 15 seconds).
3. 'Emergency Source Available' light should come on.
4. Transfer switch moves to Emergency. 'Load Connected to Emergency' light comes on, 'Load Connected to Normal' goes off.
5. Transfer to emergency may occur after a time delay (up to 5 minutes), or immediately if 'Bypass Time Delay' is pressed.
6. Transfer switch moves back to Normal. 'Load Connected to Normal' light comes on, 'Load Connected to Emergency' goes off.
7. Retransfer to Normal may occur after a time delay (up to 30 minutes), or immediately if 'Bypass Time Delay' is pressed.
8. Unloaded running (engine cooldown) delay runs the generator for 5 minutes. Generator stops, 'Emergency Source Available' light goes off.

Figure 1-6 Description: Diagram similar to Figure 1-5, illustrating standard controls and indicators, with emphasis on the 'TRANSFER SWITCH TEST' and 'BYPASS TIME DELAY' buttons.

This completes the Functional Test. Leave the engine-generator starting control in the automatic position.

Section 2: Sequence of Operation

Transfer To Emergency:

The sequence begins automatically when normal source voltage falls below the preset dropout point or when the 'Transfer Switch Test' button is pressed. An under-voltage condition on any phase of the normal source is detected by the sensor.

When the normal source fails or the test button is pressed, the SE relay de-energizes, and relay NR begins its timing cycle (1 or 3 seconds momentary normal source outage delay). This delay prevents nuisance generator starting. If normal source voltage returns before the delay expires, the cycle resets. If not, NR relay de-energizes, signaling the generator to start. A voltage and frequency sensor monitors the emergency source, accepting it only when preset pickup points are reached (typically 10 seconds after NR relay dropout).

If the 'Transfer Switch Test' button is pressed, it must be held for 15 seconds. If the emergency source is immediately available, it may be accepted as soon as NR relay drops out.

When the emergency source is accepted, relay ER begins its timing cycle (transfer to emergency delay, 0-5 minutes). For immediate transfer, press 'Bypass Time Delay'. ER relay energizes, the TS coil is energized, and the transfer switch operates, supplying the load from the emergency source.

The switch remains in Emergency until the normal source is restored or the retransfer delay times out if the test button was used.

Figure 2-1 Description: Diagram of membrane controls and indicator lights, showing the 'LOAD CONNECTED TO', 'SOURCE AVAILABLE' lights, and buttons for 'TRANSFER SWITCH TEST', 'BYPASS TIME DELAY', 'SET ENGINE EXERCISER'. It also shows indicator light behavior for setting the exercise period.

Retransfer to Normal:

The sequence begins when the voltage sensor detects normal source restoration. The voltage must rise above preset pickup points on all phases.

When the normal source is accepted, relay SE begins its timing cycle (retransfer to normal delay, 1 sec. to 30 min.). For immediate retransfer, press 'Bypass Time Delay'. This delay prevents immediate retransfer until the normal source stabilizes. If normal source voltage drops below the dropout point before the delay expires, the cycle resets. If the emergency source fails for more than 4 seconds during the cycle, ER relay drops out, and the load is immediately retransferred to the normal source if acceptable.

SE relay energizes, ER relay drops out, the TS coil energizes, and the transfer switch operates, supplying the load from the normal source.

Upon retransfer, NR relay begins its timing cycle (unloaded running delay/engine cooldown, 5 minutes). NR relay energizes after the delay, signaling the generator to shut down. All circuits reset.

Activation of control features in Section 5 can alter the sequence and introduce additional time delays.

Section 3: Testing & Service

Preventive Maintenance

Regular maintenance ensures high reliability and long life. Operate the switch monthly, performing the four-step Electrical Operation Test with load transfer.

Annual Inspection: De-energize all sources. Brush and vacuum dust. Remove barriers, check contact condition, and replace if pitted or worn. Reinstall barriers carefully.

Lubrication: The transfer switch is properly lubricated. Renew factory lubrication if subjected to severe dust or abnormal conditions. Relubricate operator if TS coil is replaced. Order lubrication kit 75-100.

Replacement Parts: Order parts using the Serial No. and Catalog No. from the transfer switch nameplate. Contact your local ASCO Power Technologies sales office.

Disconnecting the Controller

Harness disconnect plugs are for repair purposes only. If the controller must be isolated, follow these steps:

Disconnecting the Plugs

WARNING: Do not unplug the controller until step 1a or 1b is completed.

1. Observe transfer switch position:
• Normal position: Set standby engine control to OFF. Open emergency source circuit breaker.
• Emergency position: Open normal source circuit breaker. Set engine starting control to TEST or RUN. Open emergency source circuit breaker.
2. Separate quick disconnect plugs by squeezing latches; do not pull wires.
3. Label, remove, and tape signal wires connected to engine start terminals (TB1 and TB3, or TB1 and TB2).

Reconnecting the Plugs

WARNING: Do not reconnect until step 1a/1b and 2 are completed.

1. Observe transfer switch position:
• Normal position: Ensure standby engine control is OFF. Emergency source circuit breaker should be open.
• Emergency position: Normal source circuit breaker should be open.
2. Reconnect signal wires to engine start terminals.
3. Align and press harness plugs and sockets straight in until latches click.
4. Restore the opposite source:
• Normal position: Set standby engine control to AUTOMATIC. Close emergency source circuit breaker.
• Emergency position: Close normal source circuit breaker. Load will retransfer to normal after delay. Press BYPASS TIME DELAY for immediate retransfer. Set engine starting control to AUTOMATIC.

Manual Load Transfer

This procedure manually transfers the load if the controller is disconnected.

WARNING: Do not manually operate the transfer switch until both power sources are disconnected.

1. Open normal and emergency source circuit breakers.
2. Use the maintenance handle to manually operate the transfer switch to the opposite source (See page 1-3).
3. If in Emergency position, manually start the engine generator and close the emergency source circuit breaker.

Trouble-Shooting

Review control features and their operation. WARNING: Proceed with care; the automatic transfer switch is energized.

Motor Load Transfer Feature Troubleshooting:

DANGER: Use extreme caution when measuring voltages.

1. Connect voltmeter (set for twice system phase-to-phase voltage) between Transfer Switch terminals NA and EA.
2. Manually start generator. Voltmeter needle should sweep regularly between 0 and twice system voltage.
3. Press and hold TRANSFER SWITCH TEST button. Load should transfer to emergency when meter needle is near 0 volts. If not, feature is not operating.
4. Release button. Load should retransfer to normal after Retransfer to Normal Delay. Retransfer should occur when needle is near 0 volts. If not, feature is not operating.
5. For immediate retransfer, press BYPASS TIME DELAY button. Disconnect voltmeter.

If problems persist, contact ASCO Power Technologies sales office with Serial No., BOM No., and Catalog No.

Section 4: Adjustments

Time Delay Adjustment

Standard time delays are set to customer specifications. Use Table 4-1 for values and corresponding DIP switch or potentiometer settings. Refer to page 4-2 for adjustment procedures.

Sensor Adjustments

Voltage and frequency sensor pickup/dropout points are set to customer specifications. Use Tables 4-2 and 4-3 for settings and DIP switch actuators. Refer to page 4-2 for procedures.

WARNING: Changing settings may affect normal operation and could leave load circuits connected to a low voltage source.

* If dropout voltage is set to 90%, the pickup voltage must be set to 95%.

How to Change a Setting

WARNING: Do not make any setting changes while the controller is energized.

1. Prevent transfer switch operation by disconnecting one source, then the other:
• Normal position: Open emergency source breaker, set engine starting control to OFF, then open normal source breaker.
• Emergency position: Open normal source breaker, set engine starting control to TEST or RUN, then open emergency source breaker.
2. Disconnect both harness plugs from the controller by squeezing latches.
3. Remove the controller cover by releasing the latch.
4. Locate the potentiometer or DIP switch for the desired setting (refer to tables and figures on pages 4-1 and 4-2).
5. Potentiometers: Use a small screwdriver to turn clockwise to increase time delay, counterclockwise to decrease.
6. DIP Switches: Use a ball-point pen or similar tool to slide actuators left (off) or right (on) to match the illustration. Recheck the setting.
7. Reinstall the controller cover.
8. Reconnect both harness plugs, aligning and pressing until latches click.
9. Close the enclosure door, then restore both sources:
• Normal position: Close normal source breaker, then emergency source breaker.
• Emergency position: Close normal source breaker. Load will retransfer automatically after delay. Press BYPASS TIME DELAY for immediate retransfer. Close emergency source breaker.
10. Turn the engine starting control to AUTOMATIC.

Figure 4-1 Description: Diagram showing the controller cover latch mechanism.

Figure 4-2 Description: Diagram showing the location of potentiometers and DIP switches (S1, S2, S3) on the controller board, including the 9-volt battery and time delay jumpers.

Figure 4-3 Description: Diagram illustrating how to change time delay potentiometers (P1 or P2) by turning them clockwise to increase or counterclockwise to decrease.

Figure 4-4 Description: Diagram showing how to set DIP switch actuators (off/on) using a pointed tool.

Section 5: Control Features

Engine Exercisers

Timers periodically exercise the emergency engine-generator plant, with or without load transfer, or can be disabled. Exercise under load once a week for a minimum of 20 minutes, or as recommended by the manufacturer.

Built-in Engine Exerciser

Provides a weekly 20-minute exercise period. It occurs immediately when the 'SET ENGINE EXERCISER' button is pressed (and held for at least 5 seconds), and then weekly at the same time. A 9-volt battery maintains settings. The battery jumper block must be shifted to the ON position.

Shaded DIP switches are standard factory settings.

Figure 5-1 Description: Diagram of operator panel pushbuttons and status light, showing 'SET ENGINE EXERCISER' and 'BYPASS TIME DELAY' buttons, and indicating how to set the exercise period.

Exercise without Load (S1, Actuator 8 off)

1. Set Exercise Period: Press and hold 'SET ENGINE EXERCISER' button (5 sec). Status light blinks rapidly.
2. Exercise Active: Release button. Status light blinks slowly. Generator starts and runs.
3. Cancel Exercise: Press 'BYPASS TIME DELAY'. Status light stays on. Generator stops.
4. Exerciser Enabled: Status light stays on. Repeats every 7 days.

Exercise with Load (S1, Actuator 8 on)

1. Set Exercise Period: Press and hold 'SET ENGINE EXERCISER' button (5 sec). Status light blinks rapidly.
2. Exercise Active: Release button. Status light blinks slowly. Generator starts, runs, and transfers load to Emergency.
3. Cancel Exercise: Press 'BYPASS TIME DELAY'. Status light blinks slowly (during cooldown). Load retransfers to Normal, generator runs for 5 min cooldown.
4. Exerciser Enabled: Status light stays on. Repeats every 7 days.

Optional Programmable Engine Exerciser (Accessory 11CD)

Provides seven days of different exercise periods, programmable for each day with or without load. A backup battery maintains settings.

Shaded DIP switches are standard factory settings.

Figure 5-2 Description: Diagram of exerciser display and push buttons, including 'reset', 'program', 'clock', 'hour', 'minute', 'day', and '±1h' buttons.

Changing or Checking Time Programs: Use the 'Prog.' button to cycle through programmed commands for revision or checking.

Canceling Time Programs: Set hours/minutes to zero using 'h' and 'm' buttons. Press 'Res.' (reset) to clear all memory.

Manual Override: WARNING: Only override if exerciser is set for exercise without load. Failure to do so could cause injury if the transfer switch operates while the enclosure door is open.

Daylight Savings / Standard Time Change: Press the '±1h' button once to advance (Daylight Saving) or twice to revert (Standard Time).

Inphase Monitor for Motor Load Transfer

Controls transfer/retransfer of motor loads to prevent inrush current issues and nuisance tripping. Actuated by DIP switch S1 (actuator 5): right = ON, left = OFF.

NOTE: Motor Load Transfer is activated following the Load Disconnect Feature Delay Before Transfer.

Load Disconnect Feature

Connect external circuits to terminals indicated on the Wiring Diagram. The double throw (Form C) contact is rated for 28 VDC or 120 VAC (5 amps resistive). It operates prior to a selectable 0, 3, 10, or 20 second delay before transfer. The contact resets immediately after transfer or after the same pre-signal delay.

Time delay between load disconnect signal and transfer initiation is set via DIP switch S2 (actuators 6, 7, 8).

Shaded DIP switches are standard factory settings.

* Enabling Delay After Transfer causes the control signal to reset after the same delay as set for Delay Before Transfer.

Remote Control Features

Require a customer-supplied normally closed contact for a 5 V dc low energy circuit. Activate appropriate DIP switch S2 actuators.

Optional Strip Heater (Accessory 44)

Designed to maintain acceptable ambient temperatures within the ATS enclosure. Includes mounting bracket, strip heater, thermostat, and terminal block. A transformer with fuses is included for voltages above 120 V ac. The 120 V ac assembly does not include a transformer. Available factory installed or as a kit.

Turn the thermostat's dial to the required setting.

Visual Description: A diagram shows a thermostat dial with temperature markings (30°F to 140°F) and arrows indicating turning counterclockwise lowers temperature and clockwise raises temperature.

Index

Key topics covered in this manual include:

• Accessories (5-2, 5-3, 5-4, 5-5)
• Auxiliary Circuits (1-2)
• Barriers (1-3)
• Battery (4-2, 5-1)
• Buttons, Push (3-1)
• Bypass Time Delay (1-4, 2-1, 3-1)
• Cable Lugs, Preparation, Spacers (1-1)
• Catalog Number (inside cover)
• Cleaning (3-1)
• Connections (Engine control contact, Line) (1-2, 1-1)
• Contact Position Indicators (1-3)
• Control Features (5-1)
• Load Disconnect (5-4)
• Motor Load Transfer (5-4)
• Plant Exerciser (5-1)
• Controller (Control Panel) (4-1, 4-2)
• Cover Removal (4-2)
• Disconnecting (3-1)
• Time Delay Potentiometers (4-2)
• DIP Switches (4-1, 4-2, 5-1, 5-2, 5-4)
• Electrical Operation (1-4)
• Engine Exerciser (5-1, 5-2, 5-3)
• Engine Starting Contacts (1-2)
• Failure (See Trouble-shooting, 3-2)
• Features (See Control Features)
• Frequency, Pickup and Dropout Settings (4-1)
• Functional Test (1-3, 1-4, 1-5)
• Harness (1-2), Disconnect Plugs (3-1)
• Inphase Monitor (5-4)
• Inspection (3-1)
• Installation (1-1)
• Insulator Backing Piece (1-1)
• Labels (Engine starting contacts, Inputs/Outputs, Rating) (1-2, Cover)
• Lights (1-4, 5-1)
• Load Disconnect Feature (5-4)
• Lubrication (3-1)
• Maintenance, Preventive (3-1)
• Manual Load Transfer (3-2)
• Manual Operation (1-3)
• Motor Load Transfer Feature (5-3)
• Nameplate (Cover)
• Operation (Electrical, Manual, Sequence) (1-4, 1-3, 2-1)
• Parts (3-1)
• Problem (3-2)
• Programmable Engine Exerciser (5-2, 5-3)
• Rating Label (Inside Cover)
• Remote Control Features (5-4)
• Replacement Parts (3-1)
• Set Engine Exerciser (5-1)
• Settings (Changing, Factory, Frequency, Phase, Time Delay, Voltage) (4-1)
• Terminal Block (1-2)
• Test, Functional (1-3, 1-4, 1-5)
• Time Delay (Adjustment, Cooldown, How to Change, Settings, Transfer to Emergency/Normal) (4-1, 4-2)
• Timer (Plant Exerciser) (5-1)
• Transfer Switch Test (1-4, 3-1)
• Trouble-shooting (3-2)
• Voltage (Phase, Pickup/Dropout Settings) (4-1)