Siemens 3AH3 Instruction Manual page 33

Figure 20: Contact-erosion check mark dot circled in
orange (shown with circuit breaker OPEN)
High-speed moving parts.
Can result in serious injury.
Tripping spring is charged. If trip latch is moved, the stored-energy springs
will discharge rapidly.
Stay clear of circuit breaker components that are subject to sudden, high-
speed movement.
The contact-erosion check procedure is:
a) Be sure the circuit breaker primary
contacts are CLOSED.
b) Observe the white contact-erosion
mark (refer to Figure 20) of each pole.
When any part of the white contact-
erosion mark is visible, contact wear
is within acceptable limits.
4. Press the red Open pushbutton after
completing the contact-erosion check.
Visually verify the Discharged condition
of the closing spring and that the circuit
breaker contacts are OPEN.
5. Press the black Close pushbutton.
Nothing should happen. The manual-
spring check should demonstrate
smooth operation of the operating
mechanism.
Electrical control checks
The electrical controls of the circuit breaker
should be checked during inspections to
verify absence of any mechanical damage,
and proper operation of the automatic
spring-charging and Close and Trip circuits.
Unless otherwise noted, all of these tests
are performed without any control power
applied to the circuit breaker.
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