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| Illustration 1 | g01275395 |
| (1) Zig Zag Controller Board | |
The Zig Zag Controller board (1) is present only in 4-wire applications.
The board (1) is mounted on the left panel. The board (1) is required in order to establish the neutral point of the three phase output for the following reasons:
- When the system is in discharge mode
- When the system is disconnected from the utility input
The board (1) provides the stand-alone control for the proper switching of the neutral power conductor during entrance and exit of discharge.
During normal operation, the output Zig Zag Transformer is not connected to the utility neutral. When an outage is detected, the Zig Zag Controller (1) will switch the neutral of the Zig Zag Transformer (1) to the utility neutral for the duration of the discharge.
The board contains voltage and current ports that are used to detect a failure of the Zig Zag Transformer. If a need for discharge is detected, the Zig Zag Controller (1) will turn on the gates of the Silicon Controlled Rectifier (SCR). In addition, the Zig Zag Controller (1) will close an output in order to close the neutral contactor.
Refer to Systems Operation, Testing and Adjusting, RENR9988, "Internal Component Preremoval Steps (MMS System Cabinet)" in order to shut down the system and gain access to internal components.
| 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 a 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. |
- Disconnect all connectors. Verify each label for each connector for subsequent installation. Refer to Illustration 2.
- Remove the ground screw from the corner of the board (1).
- Disconnect the white plastic standoffs that connect the board (1) to the left panel.
Note: The Zig Zag Controller board (1) must be removed from the standoffs without bending the board.
- Compress the head of each standoff so that the board (1) is not locked, but the board (1) is still attached to the standoff.
- Remove the board (1) from all standoffs at the same time.
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| Illustration 2 | g01275396 |
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Diagram of the Zig Zag Controller Board | |
| 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 a 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 board (1) in the cabinet over the white standoffs that are connected to the left panel. Install the board (1). Verify that all the standoffs are locked into the correct position.
- Insert the ground screw in the board. Tighten the ground screw into the left panel.
- Connect the wire connectors. Verify the labeling of each connector for proper placement. Refer to Illustration 2.