BREAKER
MOUNTED
EQUIPMENT·
MOUNTED
Fig. 20.
Neutral sensor secondary disconnect
blocks
Power Circuit Breakers, GEI-86134
TROUBLESHOOTING
When malfunctioning is suspected, the first step
in troubleshooting is to examine the circuit breaker
and its power system for abnormal conditions such
as:
a
)
Breaker tripping in proper response to over
currents or incipient ground faults.
b
)
Breaker remaining in a trip-free state due to
mechanical interference along its trip shaft.
c
)
Inadvertent shunt trip activations.
WARNING:
DO NOT CHANGE TAPS ON
THE CURRENT SENSORS OR ADJUST
THE PROGRAMMER UNIT SET KNOBS
WHILE THE BREAKER IS CARRYING
CURRENT.
Once it has been established that the circuit
breaker can be opened and closed normally from the
test position, attention can be directed
to
the trip
device proper. Testing is performed by either of
two methods:
1. Conduct high-current, single-phase tests on
the breaker using a high current-low voltage test
set.
NOTE:
For these single-phase tests, spe
cial connections must be employed/or SST
breakers equipped with Ground Fault. Any
single-phase input to the ground differential
transformer will generate an unwanted
''ground fault" output signal which will trip
the breaker. This can be nullified either
by
(a) testing two poles of the breaker in
series,
or
(b) Using the Ground Fault Defeat Cable
as shown in Fig. 28.
This special
test cable energizes all the primary
windings of the differential trans
former in a self-cancelling, series
parallel connection so that its second
ary output is always zero.
2. Test the components of the SST system using
portable Test Set Type TAK-TSI
(
Fig. 21). The
applicable test procedures are detailed in Instruc
tion Book GEK-64454 and are summarized on the
next page.
17
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