8-4.3 Primary Contact Inspection - Eaton IZM97 Instruction Manual

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 (Figure 8-1). Begin by removing the arc
chute screws and all three arc chutes. Turn each arc chute
upside down to visually inspect the inside (Figure 8-2).
WARNING
Arc chutes must always be secured properly in place
before a circuit breaker is installed in a circuit breaker
compartment. Failure to do this could result in equip-
ment damage, bodily injury, or even death.
When the inspections are complete, position each arc chute
down over its respective set of primary contacts, and secure
in place with the screw removed earlier. Torque the arc chute
screws to 4–5 Nm.

8-4.3 Primary contact inspection

With the arc chutes removed, visually inspect each primary
contact structure for signs of wear and/or damage. The pri-
mary contacts with the circuit breaker open can be viewed
by looking directly down into the arc chamber (Figure 8-3
and Figure 8-4). A contact wear indicator is provided for each
primary contact and indicates whether or not the contact
should be replaced. Inspection of the contacts using the
contact wear indicators is conducted only with the circuit
breaker closed (Figure 8-5).
When making a contact wear inspection, alw ays make the
inspection by looking straight down into the arc chamber for
the proper perspective. Viewing the contact wear area from
an angle could distort the view.
The contact wear indicator is the relative position of the indi-
vidual contact fingers to a narrow, side-to-side ledge inside
the arc chamber. The ledge is actually part of the arc cham-
ber. When the circuit breaker is closed and the contacts are
in good condition, the narrow ledge is covered by the back
end of the contacts. If the back end of the contacts do not
totally cover the ledge, the contacts should be replaced.
WARNING
Arc chutes must always be secured properly in place
before a circuit breaker is installed in a circuit breaker
compartment. Failure to do this could result in equip-
ment damage, bodily injury, or even death.
Once the inspection is completed, be sure to put the arc
chutes back to its original place.
New generation IZM97, 99 low voltage air circuit breaker instruction manual MN013010EN February 2020 www.eaton.com.cn
NOTICE
Section 8: Inspection and maintenance
Figure 8-3 Primary contacts with circuit breaker
open(not used for contact wear inspection)
Figure 8-4 Contact inspection area with circuit breaker
open
Arcing
contact
Integral
(Toe)
arc runner
Stationary
main contact
Moving main
contact
(Side view)
99