The function of the Breaker Bell Alarm Supervisor Board is to monitor the status of the K1 and K5 circuit breakers. The Breaker Bell Alarm Supervisor Board verifies that the K1 and K5 circuit breakers open only when an open command is given. That means, in the case of the K1 breaker, that the K1 breaker opens only when the UVR power is removed. In the case of the K5 breaker, the K5 breaker opens only when a shunt trip signal is present.
If either breaker opens without the proper command, the Breaker Bell Alarm Supervisor Board interrupts the Under Voltage Relay power to the K1 breaker, thereby locking the breaker open and signaling to the system via the Static Switch GPI Board that an over-current trip has occurred. Additionally, a "K1 Over Current Shutdown Activated" message will occur in the log file. This state is also known as a "BBS Trip" or a "Breaker Bell Alarm Supervisor Trip".
The Breaker Bell Alarm Supervisor Board will stay in this state through power cycles because this state is latched by latching relays. Additionally, the Breaker Bell Alarm Supervisor Board can only be reset by the reset push button.
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| Illustration 1 | g01274141 |
Breaker Bell Alarm Supervisor Board Location, Single MMU Systems Only | |
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| Illustration 2 | g01274152 |
Breaker Bell Alarm Supervisor Board | |
The Breaker Bell Alarm Supervisor Board is located behind the middle door frame support.
Refer to Illustration 1.
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| Illustration 3 | g01341995 |
Location of the Reset Switch | |
The Reset Pushbutton is located behind the locked left door of the I/O cabinet. Refer to Illustration 3.
Reset Procedure
Note: Before pressing the Reset Pushbutton, refer to Systems Operation, Testing and Adjusting, RENR7654, "K1 Overcurrent Shutdown - Reset".
Note: 24 volts to the K1 circuit breaker is not present. Do not manually close the K1 circuit breaker.
Removal
| NOTICE |
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Electrostatic discharge can damage integrated circuits or semiconductors if you touch bus connector pins. When not in use, keep the module in its static-shield bag. Follow these guidelines when you handle any module: Touch a grounded object to discharge static potential. Wear an approved wrist-strap grounding device. Do not touch the bus connector or connector pins. Do not touch circuit components inside the module. If available, use a static-safe work station. |
- Refer to the information in the Systems Operation, Testing and Adjusting, RENR7654, "Internal Component Preremoval Steps (Input/Output Cabinet)"in order to de-energize the system and gain access to internal components.
- Disconnect all connectors from the Breaker Bell Alarm Supervisor Board.
The connectors are labeled as to their locations in the unit. Verify each connector to make sure that the label is present and legible.
Refer to Illustration 4.
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| Illustration 4 | g01274157 |
Breaker Bell Alarm Supervisor Board - Version 1 Hardware | |
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| Illustration 5 | g01274162 |
Breaker Bell Alarm Supervisor Board - Version 2 Hardware | |
- Loosen the four bolts that connect the bracket to the door frame.
- Remove the bracket and the Breaker Bell Alarm Supervisor Board from the cabinet.
- Disconnect the four white plastic standoffs connecting the Breaker Bell Alarm Supervisor Board to the bracket using the following method.
The Breaker Bell Alarm Supervisor Board must be removed from the stand-offs without bending the board.
- Pinch the head of each stand-off so that the Breaker Bell Alarm Supervisor Board is not locked to the stand-off but is still attached to the stand-off.
- Remove the board by gently and evenly pulling the Breaker Bell Alarm Supervisor Board from all stand-offs at the same time.
Installation
| NOTICE |
|---|
Electrostatic discharge can damage integrated circuits or semiconductors if you touch bus connector pins. When not in use, keep the module in its static-shield bag. Follow these guidelines when you handle any module: Touch a grounded object to discharge static potential. Wear an approved wrist-strap grounding device. Do not touch the bus connector or connector pins. Do not touch circuit components inside the module. If available, use a static-safe work station. |
- Position the Breaker Bell Alarm Supervisor Board over the four white stand-offs that are connected to the bracket.
- Push the Breaker Bell Alarm Supervisor Board, gently and evenly, onto all the stand-offs simultaneously. Make sure all stand-offs are locked in place.
- Attach the Breaker Bell Alarm Supervisor Board and bracket carefully in the cabinet with the orientation shown in Illustration 4 and Illustration 5. Use four cross tip screws.
- Plug the wire connectors into the correct connectors on the Breaker Bell Alarm Supervisor Board. Check the labels on each connector for proper placement.
Refer to Illustration 4.