GE AK-50 Series - False Tripping due to Ground Fault Detection

Fig
.
32
(
8039647
)
Magnetic
Coil
Assembly
for
AK
-
3
-
50
Breakers
3
.
Transformer
Taps
(
In
Amperes
)
4
.
Disconnect
Plug
4
,
If
the
breaker
is
equipped
with
ground
fault
protection
,
determine
whether
the
false
trip
-
ping
is
the
result
of
falsely
answering
an
over
-
current
trip
or
a
ground
trip
signal
.
This
may
be
determined
by
temporarily
eliminating
theground
trip
signal
by
shorting
out
the
ground
signal
points
1
and
5
at
the
ground
signal
terminal
board
on
the
back
frame
of
the
breaker
.
Terminals
1
and
5
can
be
identified
by
the
0.15
UF
capacitor
connected
between
them
.
(
See
drawing
138
B
2454
)
(
Fig
.
40
)
.
With
the
breaker
restored
to
service
and
with
the
ground
fault
detector
deactivated
,
establish
whether
there
is
false
tripping
due
to
overcurrent
.
FALSE
TRIPPING
CAUSED
BY
FAULTY
GROUND
FAULT
DETECTION
If
the
breaker
,
is
equipped
for
four
wire
service
(
fourth
C
.
T
.
remotely
(
Fig
.
37
)
it
is
important
that
the
shielding
be
effective
by
having
continuity
from
the
disconnect
plug
at
the
Power
Sensor
Unit
to
the
external
C
.
T
„
andfurther
that
this
shield
be
isolated
from
the
signal
conductors
.
It
is
also
important
that
continuity
exists
through
the
ground
signal
circuit
.
Check
these
conditions
as
follows
;
referring
to
Fig
.
1
.
Carrying
Fixture
2
.
Power
Supply
Coil
,
Current
Sensor
Coil
continue
carrying
current
without
overcurrent
protection
,
it
is
recommended
that
the
leads
to
the
tripping
solenoid
be
removed
to
completely
eliminate
the
possibility
of
the
breaker
tripping
.
Do
not
close
breaker
with
power
on
the
main
contacts
while
the
disconnect
plug
to
the
magnetic
coils
is
disconnected
.
1
.
Check
for
the
existence
of
overcurrent
or
ground
fault
conditions
that
may
be
causing
the
breaker
to
trip
as
a
proper
response
to
these
normal
circuit
conditions
.
2
.
The
possibility
of
the
breaker
being
trip
free
by
mechanical
interferences
along
the
trip
shaft
or
inadvertent
shunt
trip
operations
should
be
positively
eliminated
before
investigating
the
Power
Sensor
.
Successful
operations
in
the
test
position
should
be
obtained
before
proceeding
with
the
Power
Sensor
trouble
shooting
.
3
.
A
PST
-
1
Power
Sensor
Test
Kit
must
be
available
.
(
Fig
.
39
)
.
Check
the
Power
Sensor
Unit
for
correct
function
for
each
pick
up
setting
and
one
point
on
each
time
delay
characteristic
.
Then
check
for
the
correct
operation
of
each
phase
of
the
Power
Supply
Unit
.
This
procedure
is
described
in
the
instruction
manual
(
GEK
-
7301
)
for
the
PST
-
1
Test
Kit
.
If
the
test
results
for
this
test
do
not
deviate
more
than
10
%
from
the
published
curves
-
proceed
to
step
4
.
If
the
deviation
is
more
than
10
%
contact
the
factory
for
possible
replace
-
ment
of
the
Power
Sensor
Unit
.
40
.
Remove
connection
plug
at
Power
Sensor
Unit
and
check
continuity
between
A
and
C
(
Signal
)
.
Letters
are
located
on
end
of
plug
.
1
.
2
.
Check
to
be
sure
no
continuity
exists
be
-
tween
R
and
C
.
3
.
Temporarily
connect
jumper
from
shield
34
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