Page xxvi
IB131021EN
Effective Mar 2018
After the contact wipe is properly checked/set, the open
gap should be recorded on each phase. To record the
open gap, follow the steps below (Refer to Figure
5-5
):
With the circuit breaker closed, measure the
1.
distance between the drive block and the bottom of
the conductor casting. Record measurement for
each phase.
Open the circuit breaker.
2.
With the circuit breaker opened, measure the
3.
distance between the drive block and the bottom of
the conductor casting. Record measurement for
each phase.
Subtract the measurement from Step 3 from the
4.
measurement from Step 1 for each phase.
The difference between the two measurements is
5.
the Open Gap. The Open Gap should be 0.335” +/-
.020” on each phase.
IMPORTANT: Save the Open Gap measurements
6.
in maintenance records and refer to them during
maintenance intervals when Contact Erosion must
be calculated. Refer to Paragraph
6-5
for
information on Contact Erosion.
F
i
g
u
r
e
5-
3
M
e
a
s
u
r
ement of Contact Stroke
Figure 5-4 Loosening the Drive Rod Housing Jam Nut
Figure 5-5 Measurement of Contact Open Gap
5-3
ELECTROMAGNETIC MECHANISM
WARNING
KEEP HANDS AND FINGERS AWAY FROM THE
CIRCUIT BREAKER’S INTERNAL PARTS WHILE THE
CIRCUIT BREAKER CONTACTS ARE CLOSED OR THE
CAPACITORS ARE CHARGED. THE CIRCUIT
BREAKER CONTACTS MAY OPEN CAUSING A
CRUSHING INJURY OR THE CHARGED CAPACITORS
AND CIRCUITRY MAY CAUSE AN ELECTRICAL
SHOCK INJURY IF CONTACTED. DISCHARGE THE
CAPACITOR BANK AND OPEN THE CIRCUIT
BREAKER BEFORE PERFORMING ANY CIRCUIT
BREAKER MAINTENANCE, INSPECTION OR REPAIR.
Interior components of the electromagnetically actuated
mechanism can be easily accessed by removing the circuit
breaker's front cover (Figure
3-2
). The VCP-WL
mechanism & electronic controls are comprised primarily of
the electromagnetic actuator, the output plate/cam block
assemblies, the cross members, the controller, the power
supplies, and a closing coil capacitor bank (Figure
3-3
).
The mechanism allows for a circuit breaker O-CO-CO duty