1 0.4
TROUBLESHOOTING
When malfu nction ing i s suspected the fi rst step in
troubleshooting is to exam ine the c i rc u it breaker and its
power system for abnormal cond itions such as:
a) Breaker tripping in proper response to overcurrents
or inci pient ground fau lts.
b) Breaker remai ning in a tri p-free state due to
mechanical interference along its trip shaft.
c) Inadvertent shunt trip activations.
WARN ING:
DO NOT CHANGE TA PS ON THE
CURRENT SENSORS OR ADJUST THE PRO
GRAMMER UNIT SET KNOBS WHILE THE
BREA KER 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 di rected to the trip device proper.
Testing is performed by either of two methods.
1 . Conduct high-current, sing le-phase tests on the
breaker using a high cu rrent-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 appl icable test proced ures are detai led in i n
struction Book G EK-64454 and are summarized in Sec
tion 1 0.4. 1 .
The TAK-TS1 and TAK-TS2 Test Sets are portable i n
struments designed for field checking the time-current
characteristics and pickup cali bration of the SST's
various trip elements. It can verify the abil ity of the
Fl ux-Shift Tri p Device to trip the breaker and, i n add i
tion, incl udes means for. continu ity checking the phase
sensors. A TAK-TS1 Test Set is shown in Fig. 67.
The time-current characteristics for the SST Tri p
Device are g iven i n curves G ES-6033, G ES-6034 and
G ES-6035.
FIG. 67 - SST/ECS TEST SET, CAT.
NO.
TAK-TS1
5 1
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