UPS 750 Uninterruptible Power Supply Caterpillar

K3 Contactor (Bypass/Capacitor)

Illustration 1	g03690786
(1) Fuse mount bolt (2) K3 contactor

The K3 bypass contactor is located behind the left door panel of the SIO cabinet. K3 allows bypass of the UPS.

Removal

1. Refer to Systems Operation, Test and Adjust, UENR4695, "Internal Component Pre-Removal Steps". Perform the internal component pre-removal procedure to shut down the system and to gain access to internal components.

   Note: The system must be shut down before removal steps can be performed.

   Note: The contactors are heavy. Exercise caution when removing the last bolt so the contactor does not fall and damage components or personnel.

2. Remove the four screws attaching K3 cover to contactor.

3. Remove the contactor cover to expose auxiliary contacts.

4. Disconnect the K3 auxiliary contact leads K3-A1, A2, B4, C1, C2 and K3-11, 14, 21 and 14.

5. Remove the four screws that attach K3 to the SIO frame.

6. Remove the six 9/16 inch fuse mount bolts that hold the bus to the top of the contactor.

7. Remove the three 9/16 inch bolts that mount the standoff insulators located at the top of the contactor.

8. Remove the six 9/16 inch bolts that attach the bus to the bottom of the contactor.

9. Remove the six 9/16 inch bolts that attach the bus between K2 and K3 to the standoff insulators.

10. Remove the three 9/16 inch bolts that attach the bus to the top of K2.

11. Lift the bus and remove.

Installation

Place the contactor in the SIO cabinet.

1. Install the four screws that attach K3 to the SIO frame.

2. Place the bus in position.

3. Install the three 9/16 inch bolts that attach the bus to the top of K2.

4. Install the six 9/16 inch bolts that attach the bus between K2 and K3 to the standoff insulators.

5. Install the six 9/16 inch bolts that attach the bus to the bottom of the contactor.

6. Install the three 9/16 inch bolts that attach the standoff insulators at the top of the contactor.

7. Install the six 9/16 inch fuse mount bolts that attach the bus to the top of the contactor.

8. Reconnect K3 auxiliary contact leads K3-A1, A2, B4C1, C2 and K3-11, 14, 21 and 14.

9. Install the K3 cover.

10. Install four screws attaching K3 cover to contactor.

K4 Contactor (Static Bypass)

Illustration 2	g03690787
(4) Mounting bolt for contactor bus (not all are shown) (5) K4 contactor

The K4 static bypass contactor (5) is located behind the left door panel of the SIO cabinet. K4 controls the static bypass circuit to allow a rapid transfer to bypass. The K4 uses thyristors.

Removal

1. Refer to Systems Operation, Test and Adjust, UENR4695, "Internal Component Pre-Removal Steps". Perform the internal component pre-removal procedure to shut down the system and to gain access to internal components.

   Note: The system must be shut down before removal steps can be performed.

   Note: The contactors are heavy. Exercise caution when removing the last bolt so the contactor does not fall and damage components or personnel.

2. Disconnect the four 9/16 inch bolts that attach the contactor to the panel.

3. Remove the auxiliary cables.

4. Disconnect the six 3/4 inch contactor mount bolts (4) from the input/outputs buses.

5. Remove the contactor from the cabinet.

Installation

1. Position the contactor.

2. Attach the six 3/4 inch fuse mount bolts to the input/outputs.

3. Connect the auxiliary cables.

4. Connect the four 9/16 inch bolts that attach the contactor to the panel.