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Table 5: Maximum contact
resistance
52
7. Connect all points of the secondary
disconnect with a shorting wire. Connect
the shorting wire to the high-potential
lead of the high-voltage tester and ground
the circuit breaker housing. Starting with
zero volts, gradually increase the test
voltage to 1,500 volts rms, 60 Hz.
Maintain test voltage for one minute.
8. If no disruptive discharge occurs, the
secondary-control insulation level is
satisfactory.
9. Disconnect the shorting wire and re-
attach the leads to the spring-charging
motor.
10. Perform contact-resistance tests of the
primary contacts (refer to Figure 41:
Contact-resistance test of the primary
contacts). Contact resistance should not
exceed the values listed in Table 5:
Maximum contact resistance.
Inspection and cleaning of circuit breaker
insulation
1. Perform the spring discharge check on the
circuit breaker after all control power is
removed. The spring discharge check
consists of:
A. Depressing the red trip pushbutton
B. Depressing the black close
pushbutton, and
C. Depressing again the red trip
pushbutton.
All of these controls are on the circuit
breaker front panel. Visually verify the
DISCHARGED condition of the springs.
2. Remove phase barriers as shown in Figure
7: Circuit breaker primary disconnects on
page 13.
Continuous
current rating
non-generator circuit breaker
(A)
25 kA
1,200
40
2,000
35
3,000
----
3. Clean barriers and post insulators using a
clean cloth dipped in isopropyl alcohol.
4. Replace all barriers. Check all visible
fasteners again for condition and
tightness.
Note: Do not use any cleaning compounds
containing chlorinated hydrocarbons such as
trichlorethylene, perchlorethylene or carbon
tetrachloride. These compounds will damage
the phenylene ether copolymer material used
in the barriers and other insulation on the
circuit breaker.
Functional tests
Refer to the "Installation checks and
functional tests" section of this instruction
manual on pages 9 to 13. Functional tests
consist of performing at least three manual
spring-charging checks and three automatic
spring-charging checks. After these tests are
complete, and the springs fully discharged, all
fasteners and connections are checked again
for tightness and condition before re-
installing the circuit breaker into the metal-
clad switchgear.
Figure 41: Contact-resistance test of the primary
contacts
Contact resistance (micro-ohms)
Type GMSG
All others
63 kA
35
30
30
30
30
30
Type GMSG-GCB
generator circuit breaker
40 kA
50 kA
35
30
30
30
30
30
63 kA
30
30
30
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