Siemens 38-3AH3 38 kV instruction manual Checking the contact stroke Open the circuit breaker

2.9Tighten upper fastening bolt (31.2) on the upper pole-support (20.0) holding the vacuum interrupter firmly by its upper insulator and operate levers (48.6) by hand to see whether the movable contact moves freely. If any binding or lack of freedom is noted, loosen bolt (31.2) and adjust the vacuum interrupter in pole support by turning the vacuum interrupter and moving it slightly. Torque M16 bolt to 91-101 ft-lb (123- 137 Nm).

2.10The centering ring (28.1) has been loose and floating during installation of the vacuum interrupter. Check that the movable contact is free to move vertically without binding, and then tighten the hardware that secures the centering ring. Re-check that the movable contact is free to move vertically without binding.

2.11Attach insulating coupler (48.0) and lever (48.6) together, using pin

(48.5). Apply retaining clips. Correct pin has ends that have been generously chamfered.

2.12Open and close circuit breaker several times and then check to see that all bolted joints and devices are tight.

3.0Checking the contact stroke

3.1Open the circuit breaker.

3.2Free insulating coupler (48.0) by removing pin (48.5). The vacuum interrupter contacts must now close automatically as a consequence of atmospheric pressure.

3.3Observe the terminal clamp (29.2) through the openings on each side of the lower pole support (40.0).

Using vernier calipers measure the distance from the bottom surface of the terminal clamp to the bottom edge of the cutout opening. Measure carefully and record your result.

3.4Connect the insulating coupler (48.0) using pin (48.5) and the retaining clips provided.

3.5Repeat the measurement described in step 3.3 again with care to maximize accuracy. Record your result.

3.6Determine difference between the measurements made under steps 3.3 and 3.5. Your result should be 18 mm to 22 mm (0.709" to 0.866 ").

3.7If you fail to achieve the listed results, carefully repeat the entire procedure making certain of your measurements.

3.8Loosen locking nut on eye bolt on insulated coupler (48.0), and retain position of the eye. Make adjustments in one-half turn increments. After adjustment is completed, tighten eye- bolt locking nut to 26-34 ft-lb

(35 to 45 Nm).

4.0After eye bolt is tightened to proper torque, repeat all measurement procedures, making certain they are in agreement with values indicated in step 3.6.

5.0Complete all other maintenance procedures. Completely reassembled circuit breaker should pass high- potential test before it is ready for service.

Hydraulic shock absorber

The type 38-3AH3 mechanism is equipped with hydraulic shock-absorber and a stop bar that functions when the circuit breaker opens (refer to Figure 15: Stored-energy operating mechanism on page 20). The shock absorber (61.8) should require no adjustment. However, at maintenance checks, the shock absorber should be examined for evidence of leaking. If evidence of fluid leakage is found, the shock absorber must be replaced to prevent damage to the vacuum-interrupter bellows.