Siemens 38-3AH3 38 kV instruction manual Removal from switchgear, Checks of the primary power path

Removal from switchgear

Prior to performing any inspection or maintenance checks or tests, the circuit breaker must be removed from the switchgear. The "Installation checks and initial functional tests" section (refer to page 8) describes the removal procedure in detail. The principal steps are repeated here for information and guidance, but without the details of the preceding section.

1.The first step is to de-energize the circuit breaker. Figure 36: Trip-control pushbutton (lower button) illustrates the location of the trip control on the circuit-breaker operator panel. Depressing the trip pushbutton opens the circuit breaker prior to removal from the switchgear.

2.The second step in the removal procedure is to de-energize control power to the circuit breaker. Open the control-power disconnect device.

3.Rack the circuit breaker to the DISCONNECT position.

4.Perform the spring discharge check. This is done by first depressing the red trip pushbutton. Second, depress the black close pushbutton. Third, depress the red trip pushbutton again, and observe the spring condition indicator. It should read DISCHARGED.

5.Remove the circuit breaker from the switchgear. Refer to page 10 of "Installation checks and initial functional tests" section of this instruction manual for special instructions and precautions regarding removal of a circuit breaker not at floor level.

6.The circuit breaker can be located either on the floor or on a pallet. Each circuit breaker has four wheels and handles to allow one person to maneuver the unit on a level surface without assistance.

Checks of the primary power path

The primary power path consists of three vacuum interrupters and three upper- and three lower-primary disconnects. These components are checked for cleanliness and condition. The vacuum interrupters are also checked for vacuum integrity.

Some test engineers prefer to perform the contact-erosion check during the manual- spring charging check of the operator, since charging of the springs is necessary to place the contacts in the CLOSED position.

Also, the vacuum-integrity check is usually performed in conjunction with the high- potential test.

These instructions follow the recommendation these tests (contact- erosion/manual-spring charging check and vacuum integrity/high-potential tests) should be combined as described.

Cleanliness check

Figure 37: Type 38-3AH3 vacuum circuit breaker showing vacuum interrupters and primary disconnects (outer phase barrier removed) is a side view of the type 38- 3AH3 vacuum circuit breaker with the outer-insulating barriers removed to show the vacuum interrupter and the upper- and lower-primary disconnects.

All of these components must be cleaned and free of dirt or any foreign objects. Use a dry lint-free cloth. For stubborn dirt, use a clean cloth saturated with isopropyl alcohol (except on a vacuum interrupter).

For stubborn dirt on a vacuum interrupter, use a cloth and warm water and a small amount of mild liquid-household detergent as a cleaning agent. Dry thoroughly using a dry lint-free cloth.

Figure 36: Trip-control pushbutton (lower button)

Figure 37: Type 38-3AH3 vacuum circuit breaker showing vacuum interrupters and primary disconnects (outer-phase barrier removed)