UPS 1000S/ UPS 1200S Uninterruptible Power Supplys Caterpillar

One of each pair of phase cables that come from the Filter Inductors in the Controls Cabinet pass through each of the Current Transformers.

There are six Current Transformers in the cabinet, one for each of the six inverter modules that make up the inverter assembly.

Each Current Transformer is connected to the Digital Gate Logic Board of the corresponding Inverter module.

Each of the cable pairs that come from the Filter Inductors must be wound about each other a certain number of times before being attached to the inverter. Only one of the cables in the pair passes through the Current Transformer.

Illustration 1	g01281300
Inverter Cabinet Current Transformer Location (1) Current Transformer (CT)

Illustration 2	g01281301
Inverter Current Transformers

Removal

1. Perform steps in the Systems Operation, Testing and Adjusting, "Internal Component Preremoval Steps (Inverter Cabinet)" in order to de-energize the system and gain access to internal components.

2. Remove the four cross head screws that hold the Current Transformer to the cabinet frame.

3. Remove the three wires that connect to the top of the Current Transformer. The cables locations are labeled. Verify the labels.

4. Detach the cable that runs through the Current Transformer from the input of the Inverter module AC Fuse that corresponds to the Current Transformer being removed.

5. Unwind the cable until the Current Transformer is accessible.

6. Slide the Current Transformer off the cable.

Installation

1. Verify that the cables coming from the Controls Cabinet are wound each other in the proper manner.

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Illustration 3	g01281302
Inverter Current Transformer Wire Connections

2. Insert one of the two cables that come from the Controls Cabinet through the center hole of the Current Transformer. The cable end that connects to the Inverter AC fuse input should enter the Current Transformer through the side to which the arrow on the top of the Current Transformer points. Refer to Illustration 3.

3. Wind the cables from the Current Transformer to the Inverter module together.

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Illustration 4	g01281305
Cable to Bus Bar Connections (2) Nut (3) Belleville Washer (4) Grade 8 Coated Steel Washer (5) Bus Bars (6) Bolt (10) Lug

4. Attach the cable to the input of the Inverter module AC fuse with a bolt. Refer to Illustration 4 for hardware connections.

5. Position the Current Transformer in the cabinet with top arrow pointing down or into the cabinet as shown in Illustration 2.

6. Tighten the four cross head screws to secure the Current Transformer to the cabinet.

7. Attach the three wires to the connectors of the Current Transformer. The wires locations are labeled. Refer to Illustration 3.

8. Torque the cable to input AC fuse bus bar nuts to 95 N·m (70 lb ft).

   Note: Always torque the hex nut, not the bolt.