GE GCX51A - Control - Spring Adjustment; OHM Unit Checks; Other Checks and Tests; Torque

GEI
-
98328
OHM
Unit
Checks
a
.
Control
-
Spring
Adjustment
Be
sure
that the
relay
is
well leveled
in
its
upright
position
,
contact
should
just
touch
its
backstop
.
The
moving
b
.
Ohmic
Reach and
Angle
of
Maximum
Torque
Since
the
OHM
unit is
a
reactance
-
measuring
device
,
its
angle
of
maximum
torque
occurs
at
90
°
,
current
lagging
voltage
.
1
.
To
check
the
ohmic
reach
,
use
the
connections
shown
in
Figure
10
.
Set
the
No
.
1
tap
leads
on
100
%
and
set
the
current
at
10
amperes
.
Set
the
phase
shifter
so
that the
phase
-
angle
meter
reads
270
°
(
i
.
e
.
current
lags voltage
by
90
°
)
.
Now
vary
the
voltage
across
studs
17
-
18
until
the
point
is
found where
the
OHM
unit
contacts
just
close
.
This
pickup
point
will
be
different
for the
standard
-
and
short
-
reach forms of the
relay
,
and
also
will
depend
upon
the
setting
of
the
basic
ohmic
reach
taps
.
Table
XIV
shows the
pickup
voltage
point
for
the
intermediate
range
settings
in
the colum headed
90
°
.
A
±
3
%
variation is
permissible
.
2
.
To
check
the
angle
of
maximum
torque
use
the
same
connections
and
settings
as
in
(
1
)
above
except
now
set
the
phase
shifter
so
that the
phase angle
meter
reads
315
°
(
i
.
e
.
current
lags voltage
by
45
°
)
.
Again
vary
the
voltage
across
studs
17
-
18
until
the
point
is
found where the
OHM
unit
contacts
just
close
.
These
points
are
listed
in
Table
XII
for the standard
-
and
short
-
reach forms
of
the
relay
in
the
column headed
45
°
.
A
+
3
%
variation
is
permissible
.
Note
that the
relays
are
normally
shipped
from
the
factory
with
the
basic
minimum
reach
adjustment
taps
on
the
intermediate
setting
,
that
is
,
0.2
ohms
for the
short
-
reach form
and
0.5
ohms
for the standard
-
reach
form
.
TABLE XII
OHM
UNIT
CHECK POINTS
OPERATING
P
0
INTS
(
V
17
_
18
)
I
LAGS
V
BY
+
Z
-
3
%
BASIC
MIN
REACH
SETTING
NO
.
1
TAP
SET
CURRENT
RELAY
900
450
AT
:
8.4
V
14.1
V
0.2
Ohms
0.5
Ohms
100
%
6
V
Short Reach
Stand
.
Reach
T
5
A
100
%
10
A
10
V
Other
Checks
and
Tests
In
addition
to
the
tests
on
the
OHM
and
MHO
units
,
it is
recommended
that
the
following
general
tests
and checks
be
made
as
a
part
of the
ACCEPTANCE
TEST
routine
.
OHM
-
Unit
Transfer
Relay
(
0
X
1
a
.
The
OHM
-
unit
transfer
relay
,
identified
as
OX
in
Figure
8
,
is
provided
with
a
voltage
-
selection
link
to
adapt
it
for
application
on
48
,
125
or
250
volt
DC
control
.
position
.
that the
OX
unit
picks
up
at
80
%
or
less
of the
nominal
tap
voltage
for
each
link
position
.
The
unit
should
be
checked for
correct
operation
on
each
link
Apply
a
variable
source
of
DC
voltage
across
studs
12
-
13
and
check
18
Courtesy of NationalSwitchgear.com