GE GCX51A - Overall Tests

GE
1
-
98328
necessary
to
change
the
tap
setting
,
follow
the
procedure
outlined
in
the
section
on
ACCEPTANCE TESTS
under
Target
Seal
-
In
Unit
.
3
.
If
the
relay
being
tested
is
a
Type
GCX
51
B
,
the
pickup
of the
overcurrent
unit
(
OC
)
should
be
checked
.
This
can
be done
by
adjusting
the
fault
current
level
by
means
of
the
loadbox
(
Figure
12
)
.
Calibration
points
of
the
OC
unit
are
marked
on
the
relay
nameplate
.
Normally
the
overcurrent
unit is
set
at
the
factory
for
its minimum
pickup
.
Pickup
of the
OC
unit
can
be
set
at
the desired
value
by
changing
the
position
of
the knurled
armature
on
the
plunger
rod
.
An
approximate adjustment
can
be
obtained
by
means
of
the
etched
lines
on
the
calibrating
tube
.
For
an
accurate
setting
,
connect
an
adjustable
source
of
AC
current
through
studs
5
-
6
and
set
the
armature
for the
exact
pickup required
.
Note
that
typical
pickup
points
of the
OC
unit
are
above
the
continuous
rating
of the
OHM
unit
and
transactor
coils
.
4
.
Clutch
Adjustment
Short Studs
17
&
18
(
remove
voltage
)
.
Place reach
taps
in
center
tap
.
Ohm
unit
Rating
Clutch Action
0.5
Ohm
0.2
Ohm
Slips
between
34
-
44
amps
Slips
above
60
amps
Remove
short
-
set
voltage
at
120
V
across
studs
17
&
18
,
19
&
20
.
Mho
unit
Rating
Slips
between
50
-
57
amps
Slips
above
60
amps
2.5
Ohms
1.0
Ohm
The
clutch
on
either unit
can
be
adjusted
by
inserting
a
special
flat
open
-
end
wrench underneath
the
green
composition
head
directly
above
the
spool
body
of
the front
coils
,
so
that
it
engages
with
the
flats
on
the
molded
spacer
on
the
cup
shaft
.
Hold
this
wrench
and
,
with
a
5
/
16
"
open
-
end
wrench
,
loosen
or
tighten
the
clutch
by
turning
the
nut
below
the
spring
wind
-
up
sprocket
,
clockwise
(
top
-
front
view
)
to
tighten
the
clutch
setting
;
counterclockwise
to
loosen
it
.
Turn
the
nut
d
.
Overall
Tests
An
overall
check
of
current
-
transformer
polarities
,
and
connections
to
the
relay
,
can
be
made
on
the
complete
installation
by
means
of the
test
connections
and
tabulation
in
Figure
31
.
A
check
of the
phase
-
angle
-
meter
readings
shown
in
the
table
for the
power
factor
angle
and
phase
sequence
involved
will
indicate
whether the
relay
is
receiving
the
correct
voltage
and
currents
for the
conventional connections
shown
in
Figure
3
.
For
another
overall
test
,
remove
the
lower
connection
plug
from the
relay
,
disconnecting
the
current
circuits
.
The
MHO
unit
should
develop
strong
torque
to
the
right
with
normal
voltage
on
the
relay
.
Now
replace
the
lower
plug
and
open
the
E
2
taps
on
the
main
tap
block
.
If
the
direction
of
power
and
reactive
flow
25
Courtesy of NationalSwitchgear.com