Allowing the current to charge the bus slowly through the resistors to limit the in-rush current during pre-charge. Once the system reaches a nominal value as measured by the DC measurement circuit in the High Voltage Interface Board, the K7 contactor closes, bypassing the load resistors and boosts the voltage to full operating levels.
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| Illustration 1 | g01277295 |
Controls Cabinet Back Panel (29) Customer Contacts Interface Board #2 (Optional) (30) DC Bus Pre-charge Circuit Resistors (31) T1 - T4 Transformers (32) Power Supply Board (PWS) (33) Customer Contacts Interface Board #1 (34) Power Supply Board (PWS) (35) Thermistor (36) Fuse F69 (37) Fuses F88-F90, F70-F72 (38) Zig-Zag Transformer (39) K7 Pre-charge Contactor (40) K6 Pre-charge Contactor | |
Removal
- Perform the steps in the Systems Operation, Testing and Adjusting, "Internal Component Preremoval Steps (Controls Cabinet)" in order to de-energize the system and gain access to internal components.
- Disconnect the wires from the contactor. The wires locations are labeled. Verify the labeling of the wires for subsequent installation.
- Remove the rail stop on the bottom of the Contactor by unscrewing the two screws and sliding the rail stop off the rail.
- Remove the Contactor by sliding the Contactor off the rail.
Installation
- Attach the wires to the Contactor.
The wires are attached first. The wires are difficult to connect when the contactor is installed. The wires locations are labeled. Refer to Illustration 2 for wire connections.
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| Illustration 2 | g01277843 |
- Attach the contactor to the rail on the rear panel of the cabinet. Attach the contactor by placing the left (A1) side of the contactor over the left side of the rail. When the contactor is attached to the rail snap the right side of the contactor onto the rail. Refer to Illustration 1 for placement.
- Slide the rail stop over the rail from the bottom side. Fasten the two screws in place.