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Maintenance
All of these components must be clean and free of dirt or
foreign objects. Use a dry lint-free cloth. For stubborn dirt,
use a clean cloth saturated with denatured alcohol (except
for the vacuum interrupters). For stubborn dirt on a vacuum
interrupter use a damp cloth and then thoroughly dry us-
ing a dry lint-free cloth.
The phase barriers are attached to the circuit breaker to
provide suitable electrical insulation between the vacuum
interrupter primary circuits and the housing.
Always re-install the phase barriers carefully to the original
location prior to inserting the circuit breaker in the housing.
Primary Disconnects
When the primary studs are mated with the switchgear's
primary disconnects, there is forceful contact distributed
over a wide area. This maintains low current flow per indi-
vidual contact finger.
Inspect the contact fingers (cubicle mounted) for any evi-
dence of burning or pitting that would indicate weakness
of the contact finger springs.
Inspect the primary studs for physical integrity and absence
of mechanical damage.
Inspect the flexible connectors that connect the bottom
movable contacts of the vacuum interrupters to the lower
Figure 6. Primary Power Path
primary copper bars for tightness and absence of mechani-
cal damage, burning, or pitting.
Using a clean cloth saturated with denatured alcohol, clean
old lubricant from primary studs, and apply contact lubri-
cant in a very thin layer.
Fastener Check
Inspect all fasteners for tightness. Both lock-nuts and re-
taining rings are used. Replace any fasteners that appear
to have been frequently removed and replaced.
Interlock Mechanism
Wipe interlock mechanism clean and apply lubricate on
sliding, rotating, and articulating surfaces.
MOC Actuator System
MOC Actuator System should be inspected — refer to
Table 2, "Periodical Maintenance and Lubrication Tasks".
Maintenance of the circuit breaker MOC actuator system
DOES NOT mitigate the requirement to maintain cubicle
mounted MOC system components. These shall be main-
tained in accordance with the OEM's recommendations.
Electrical Control Checks
Check of the Wiring and Terminals
1. Physically check all of the switchgear wiring for evidence
of abrasion, cuts, burning or mechanical damage.
2. Check all terminals to be certain they are solidly attached
to their respective device.
Electrical Close and Trip Check (Control Power Required)
A check of the circuit breaker control circuits shall be per-
formed. This check is made with the circuit breaker ener-
gized by control power either from the switchgear or an
external control power source.
1. Once the circuit breaker springs are charged, move the
switchgear Close/Trip switch to the Close position.
There should be both the sound of the circuit breaker
closing and indication that the circuit breaker contacts
are closed by the main contact status indicator.
2. As soon as the circuit breaker has closed, the automatic
spring charging process is repeated.
3. After a satisfactory close operation is verified, move the
switchgear Close/Trip switch to the Trip position. Verify
by both sound and contact position that the contacts
are open.
4. After a satisfactory open operation is verified, hold the
circuit breaker manual Trip button and apply and main-
tain an electrical Close signal. The circuit breaker should
close, immediately trip, the close spring should charge,
and the circuit breaker should not attempt to close.
Completion of these checks demonstrates satisfactory op-
eration of auxiliary switches, internal relays and solenoids.
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