47
User Manual
MN013016EN
Effective July 2022
Magnum PXR and Power Defense SB low
voltage power circuit breakers user manual
EATON
www.eaton.com
Inspection procedures
Arc chute inspection
Table 15. Pre-inspection conditions
Device
Position of poles
Mechanism
Device position in cassette
Fixed
Open
Closed
Charged
Discharged
—
—
—
—
Drawout
Open
Closed
Charged
Discharged
Connected
Test
Disconnected
Removed
When a circuit breaker experiences a high level fault or during regularly scheduled maintenance periods, the circuit breaker’s arc chutes and
arc chambers should be inspected for any kind of damage or dirt . Be especially alert for signs of significant erosion
of the V-shaped plated inside the arc chute .
Arc chutes fit inside the arc chambers and down over the primary
contacts . Each arc chute is held in place by one top inserted screw .
Procedure
1.
Remove arc chute screws and all arc chutes from the
arc chamber .
2.
Turn each arc chute upside down and visually inspect the inside .
3.
Be sure to look for erosion and sooty discoloration on the splitter
plates and insulating jacket . If arc chutes show severe signs of
erosion or discoloration, replace with a new arc chute .
ote:
N
Because the arc chutes are removed, this is an ideal time to inspect
the primary contacts for wear (See Primary Contact Inspection
)
4.
When the inspections are complete, position each arc chute over
its respective set of primary contacts, and secure in place with
the screw(s) removed earlier . Be sure to torque arc chute screws
to 35 to 45 in-lb .
Figure 75. Top rear view of circuit breaker with one
arc chute removed
Figure 76. Bottom view of arc chute
Arc chute
removed
Baffled cover
Arc chamber
Alternating “V”
shaped
plates
