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Siemens 38-3AH3 38 kV Instruction Manual page 58

Vacuum circuit breaker
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58
Overhaul
2.9 Tighten 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).
2.10 The 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.
2.11 Attach 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.
2.12 Open and close circuit breaker several
times and then check to see that all
bolted joints and devices are tight.
3.0 Checking the contact stroke
3.1 Open the circuit breaker.
3.2 Free insulating coupler (48.0) by
removing pin (48.5). The vacuum
interrupter contacts must now close
automatically as a consequence of
atmospheric pressure.
3.3 Observe 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.
3.4 Connect the insulating coupler (48.0)
using pin (48.5) and the retaining
clips provided.
3.5 Repeat the measurement described in
step 3.3 again with care to maximize
accuracy. Record your result.
3.6 Determine 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 ").
3.7 If you fail to achieve the listed results,
carefully repeat the entire procedure
making certain of your
measurements.
3.8 Loosen 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).
4.0 After eye bolt is tightened to proper
torque, repeat all measurement
procedures, making certain they are in
agreement with values indicated in
step 3.6.
5.0 Complete 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.

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