UPSB220 Uninterruptible Power Supply Caterpillar

AC Filter Capacitor Overview

The UPSB220 contains harmonic filter circuits which contain AC capacitors that require maintenance. The AC capacitors are located at the rear of the UPS.

The AC filter capacitors can be removed from the rear side or front side of the UPS. The AC filter capacitors can be accessed from the rear side by removing the rear panel of the UPS. The AC filter capacitors can be accessed from the front of the UPS by removing the DC capacitor bank assembly.

Note: If the UPS installation does not permit access to the rear panel of the UPS, Caterpillar suggests that the AC filter capacitors be replaced at that same time as the DC capacitors.

Refer to the Testing and Adjusting Manual, UENR1798, "DC Capacitor - Replace" for information concerning removal and installation of the DC capacitor assembly.

AC Filter Capacitor Circuitry

Illustration 1	g02553056
(1) AC Filter Capacitors

AC Filter Capacitor Location

Illustration 2	g02553076
AC Filter Capacitors

Removal Procedure

Note: The following procedures provide instruction to remove the capacitor assembly through the front or rear side of the UPS.

1. The UPSB220 must be de-energized for the following procedure. Confirm that the Mains 1 and Mains 2 upstream breakers are tagged out and locked out.

2. The required PPE must be put on.

3. Use the Fluke meter to verify that no AC or DC voltage is present.

   1. Verify that the Fluke meter is working properly with a known AC source. Use the AC scale.

   2. Verify that the Fluke meter is working properly with a known DC source. Use the DC scale.

   3. Measure for AC voltage at Q1. Measure for voltage phase-to-neutral and phase-to-phase.

   4. Measure for DC voltage plus-to-minus at the DC capacitors.

4. After no voltage is confirmed, the PPE can be removed, except for safety glasses.

5. Ensue that all cables and components are appropriately labeled before removal.

Filter Capacitor Assembly Removal from the Rear Side of the UPS

1. Remove the rectifier/charger module.

   Refer to the Testing and Adjusting Manual, UENR1798, "DC Capacitor - Replace" for information concerning removal and installation of the rectifier/charger module.

2. There are two mounting screws for the AC filter capacitor assembly behind the rectifier/charger module. Remove the two mounting screws for the AC filter capacitor assembly.

3. Remove the rear panel.

4. Remove the cable ties that are around each of the AC capacitors.

5. Disconnect the wiring that is attached to the AC capacitors.

6. Remove the mounting bolts for the AC capacitor assemblies. Remove the AC capacitor assemblies.

Filter Capacitor Replacement

Note: Before beginning the installation, verify that all of the new capacitors have the same date codes and are all from the same supplier.

1. Remove all of the mounting bolts for the original capacitors to separate the capacitors from the mounting plate.

2. Replace all of the old capacitors with a new set of capacitors.

3. The capacitor mounting bolts to the mounting plate must be torqued to 7 N·m (5.2 lb ft).

Filter Capacitor Assembly Installation from the Rear Side of the UPS

Note: Do not replace the cable ties that were around each of the original capacitors. The original cable ties around each of the capacitors were installed to help prevent damage during transportation.

1. Install the filter capacitor assemblies. Tighten the assembly mounting bolts.

2. Install the two mounting screws for the AC filter capacitor assembly that are behind the rectifier/charger module location.

3. Install the wiring that was removed from the AC filter capacitors. The nuts that secure the cables to the capacitors must be torqued to 7 N·m (5.2 lb ft).

4. Install the rear panel.

5. Install the rectifier/charger module. Connect all wiring that was removed.

6. Perform a startup. Validate that UPS operation is correct.

Filter Capacitor Assembly Removal from the Front of the UPS

1. The instructions for DC capacitor replace must be used to begin the procedure. Refer to the following note.

   Note: Refer to the Testing and Adjusting Manual, UENR1798, "DC Capacitor - Replace" for information concerning removal and installation of the DC capacitor assembly.

2. After the DC capacitor assembly has been removed, remove the two mounting screws for the AC filter capacitor assembly that are behind the rectifier/charger module.

3. Remove the cable ties that are around each of the AC capacitors.

4. Remove the cable ties that secure the wiring for each of the AC capacitors.

5. Remove the AC filter capacitor assembly mounting bolts.

6. Position the AC capacitors to access the wiring connected to the capacitors. Disconnect the capacitor wiring.

7. Remove the AC capacitors assemblies.

Filter Capacitor Replacement

Note: Refer to the Testing and Adjusting Manual, UENR1798, "AC Filter Capacitor - Replace" for information concerning replacement of the AC capacitors.

Filter Capacitor Assembly Installation from the Front of the UPS

1. Position the AC capacitors to allow the wiring to be connected. Install the wiring that was removed from the AC filter capacitors. The nuts that secure the cables to the capacitors must be torqued to 7 N·m (5.2 lb ft).

2. Install the AC capacitor assemblies.

   Note: Do not replace the cable ties that were around each of the original capacitors. The original cable ties around each of the capacitors were installed to help prevent damage during transportation.

3. Install the two mounting screws for the AC filter capacitor assembly that are behind the rectifier/charger module.

4. Follow the instructions for installation the DC capacitor assembly and all of the modules that were removed.

5. Perform a startup. Validate that UPS operation is correct.