Powered by Safety
®
57
Maintenance
01.4IB.77020
A label is supplied on each vacuum
interrupter with the original setting and
end-of-life dimension for that particular
interrupter installed on each circuit breaker.
Repeat the process for all 3 poles.
When the measurement reaches the
end-of-life value given on the label, the
vacuum interrupter should be replaced.
If the field measurement differs from the
value on the label by more than 0.01 inches,
recheck the measurement and inspect
the breaker for evidence of shifting. If no
damage can be found and numbers still do
not match, consult Powell Service Division
for further instruction.
2) Sliding Contact Finger Wear
The 5kV PowlVac-ND® and
PowlVac-NDA™ Series 4 circuit breakers
use a multi-contact assembly located
inside the lower contact block and in direct
contact between the moving stem of the
vacuum interrupter and the lower contact
block. Each lower contact block also uses
polymer bushings to support and align
the movement of the vacuum interrupter’s
moving stem. Because the current
transfer mechanism is located inside the
lower contact block and shielded from
the outside atmosphere by the polymer
bushings, no scheduled preventative
maintenance is required for the sliding
contacts.
3) Vacuum Integrity
Refer to
Ch 4 Installation, D. Placing the
for information
on vacuum integrity and testing of vacuum
interrupters.
4) Mechanical Adjustment of Vacuum Interrupters
There are no adjustments required
for routine maintenance of a vacuum
interrupter assembly. There are several
factory adjustments which will vary over
the operating life of the vacuum interrupter.
Adjustments of these settings are only
necessary when repair requires the removal
or replacement of the vacuum interrupter.
Do not adjust these settings unnecessarily as
damage to the circuit breaker may result.
!
CAUTION
When it is necessary to remove or replace
the vacuum interrupter it should only be
done by a qualified technician or a Powell
service technician. Contact Powell for
further assistance at 1.800.480.7273.
D. o
ptIonAl
M
AIntenAnce
p
roceDureS
1) High Potential Tests
High potential tests are not required for
routine maintenance but are recommended
after a heavy fault interruption, any major
circuit breaker repair that involves the
primary current path or when the circuit
breaker has been in storage for an extended
time, especially in a damp location or
other adverse environment. In these cases,
both the High Voltage Insulation Integrity
and Control Voltage Insulation Integrity
tests should be performed. For details of
maintenance procedures, see
Ch 4 Installation, D. Placing the Circuit
.
