1 0.4
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 overcurrents
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 PRO
GRA MMER UNIT SET KNOBS WHILE THE
BREAKER IS CARRYING CURRENT.
Once it has been established that the circuit breaker
can be operated and closed normally from the test posi
tion, 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, special con
nections must be employed for SST breakers
equipped with Ground Fault. Any single-phase in
put 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.
71.
This special test cable energizes all the
primary windings of the differential transformer in
a self-cancelling, series-parallel connection so
that its secondary output is always zero.
2. Test the components to the SST system using por
table Test Set Type TAK-TS1 (Fig. 67) or TAK-TS2.
The applicable test procedures are detailed in i n
struction Book
GEK-64454
and are summarized in Sec
tion 1 0.4.1 .
The TAK-TS1 and TAK-TS2 Test Sets are portable in
struments designed for field checking the time-current
characteristics and pickup calibration of the SST's
various trip elements. It can verify the ability of the
Flux-Shift Trip Device to trip the breaker and, in addi
tion, includes means for. continuity checking the phase
sensors. A TAK-TS1 Test Set Is shown in Fig. 67.
The time-current characteristics for the SST Trip
Device are given in curves
G ES-6033, G ES-6034
and
GES-6035.
FIG. 67 - SST/ECS TEST SET, CAT. NO. TAK-TS1
51
www
. ElectricalPartManuals
. com
