Citadel 2.0 - Instruction Manual - page:
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Customers should develop their own switchgear testing plan and data collection
methodology prior to receiving switchgear and placing it in service. Baseline micro-ohm
readings should be obtained by well-trained technicians using calibrated, certified utility
grade test equipment only. A micro-ohm test set rated at least a 100 amp continuous
with filtered output current should be used. Micro-ohm readings for the breaker’s
vacuum interrupters (VI) should be taken by making a good solid connection of the test
set leads across the vacuum interrupter (VI) directly. Do not include any bolted joints,
run back copper or finger clusters so that the baseline micro-ohm readings for the new
vacuum interrupters are reflectively accurate. Additional micro-ohm baseline readings
should be taken at the far end of the runbacks and on a piece of copper identical in
size and geometry to the stationary primary disconnect bottle’s conductor that is firmly
inserted into the finger cluster. This will provide Users with baseline end-to-end micro-
ohm readings across the breaker’s entire power pole assemblies.
Regular testing by Users over the life of the breaker should include the retesting and
comparison of these values.
Interrupter micro-ohm readings in and of themselves are not a preferred indicator of
interrupter health.
Additionally; end to end readings are important to verify the quality of bolted
connections, clamp connections, braid assemblies, finger cluster spring pressure and
breaker mechanism / push rod closing pressure.
Should any of the following conditions develop;
•
VI does not hi-pot properly per ANSI in-service standards for switchgear of that
voltage class.
•
The breaker’s # of operations vs. interruption current is higher than depicted at the
indicative point on the VI’s Life Expectancy Curve.
•
The VI contact erosion indicator is no longer visible (verify it was not un-view-ably
rotated during initial assembly).
•
The micro-ohm readings have increased by more than 100% of the initial readings.
Push-rod spring pressure must be validated to achieve proper micro-ohm readings.
•
The VI lower stem (moving terminal) temperature under full load (or less) current
exceeds 105 degree C.
Send the breaker back to the manufacturer for servicing and parts replacing.
V A C U U M I N T E R R U P T E R / O P E R A T O R
