Troubleshooting; Neutral Sensor Secondary Disconnect Blocks - GE AKR Series Maintenance Manual Supplement

Power Circui| Breakers, GEI-J6134
BREAKEFI.
MOUNTED
Fig.
20.
Neutral sensor secondary disconnect
blocks
IROUBTESHOOTING
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.
Breaker remaining in a
trip-free
state due to
mechanical
interference along
its
trip
sha-ft.
Inadvertent shunt
trip
activations.
WARNING: DO
NOT
CHANGE TAPS
ON
THE
CURRENT SENSOES
Oft
ADJUST
THE PROGRAMMER UNIT
SET
KNOBS
WHILE THE
BREAKER
15
CARRYING
CURRENT.
Once
it
has been
established
that
the circuit
breaker
can
beopenedand
closednormally 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-
cinl
cormections
mustbe employedfor
SST
breakers equippedwith
Ground
Fault.
Any
single -phase i;nfut
to
the
ground differential
transformer
will
generate
cn
zmwanted
"ground
fault't output
signal which
utill 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
sho?,m
in
Fig.
28.
This
special
test
cable energizes
all
the pri.mary
windings
of
the differential
trans
-
former in a
self-cancelling, series-
parallel
connection
so
that i.ts 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 a-re detailed in Instruc-
tion Book
GEK-64454
and
are summarized on
the
next page.
b)
c)
REAR VIEW
-
AKR
-50
EQUIPMENT.
MOUNTED
t7