Inspection Procedures; Table 15. Pre-Inspection Conditions; Figure 75. Top Rear View Of Circuit Breaker With One Arc Chute Removed; Figure 76. Bottom View Of Arc Chute - Eaton Magnum PXR User Manual

Magnum PXR and Power Defense SB low
voltage power circuit breakers user manual

Inspection procedures

Arc chute inspection

Table 15. Pre-inspection conditions

Device Position of poles
Fixed Open
Drawout Open
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 .
Because the arc chutes are removed, this is an ideal time to inspect
N ote:
the primary contacts for wear (See Primary Contact Inspection
procedure on page 48)
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 .
Mechanism
Closed Charged
Closed Charged
Device position in cassette
Discharged —
Discharged Connected
Arc chute
removed
Figure 75. Top rear view of circuit breaker with one
arc chute removed

Figure 76. Bottom view of arc chute

User Manual MN013016EN
Effective July 2022
— —
Test Disconnected
Baffled cover
EATON www.eaton.com
—
Removed
Arc chamber
Alternating "V"
shaped
plates
47