GE GCX51A - Angle of Maximum Torque; Ohmic Reach Adjustment

GEI
-
98328
Now
reduce
the
voltage
to
2
volts
and
set
the
current at
5.5
amperes
for
IQ
mho
units
and
4.5
amperes
for
2.5
Q
mho
units
.
Insert
the
blade
of
a
thin
screwdriver
into
one
of the slots
in
the
edge
of
the
spring
-
adjusting
ring
(
see
Figure
14
)
and
turn
the
ring
until
the
contacts
just
close
.
If
the
contacts
were
closing
below
the
4.5
ampere
set
point
,
the
adjusting
ring
should be
turned
to
the
right
.
If
they
were
closing
above
the
set
point
,
the
adjusting
ring
should
be turned
to
the left
.
Apply
2
%
of
rated
voltage
to
the
relay
.
Increase
the
current
from
4.5
to
60
amperes
;
the
contact
should
stay
closed
.
Adjust
the
core
if
this
test
does
not
function
.
Then
remove
the
potential
,
and
short studs
17
&
18
;
the
contact
should
remain
open
from
0
-
6 0
amperes
.
Both
above
tests
will
pass
if
the
core
is
in
the
proper
position
.
Figure
33
shows
an
exploded
view
of the
core
and
associated
parts
that lock
the
core
in
position
to
the unit sled
.
By
use
of the
special
wrench
,
0178
A
9455
part
1
,
the
core
can
be
rotated
in
either
direction
360
°
without
holding
the
locking
nut
"
F
"
or
having
to
retighten
after
the
final
position
of the
core
has
been
determined
.
b
.
Ohmic Reach
Adjustment
The
basic
minimum
reach
of the
MHO
unit
can
be
adjusted
by
means
of
rheostat
R
3
which
is
identified
in
Figure
1
.
Increasing
R
3
,
by
turning
the
screwdriver
adjustment
in
a
counterclockwise direction
,
increases
the
reach
of the
unit
.
Connect
the
relay
as
shown
in
Figure
10
.
Set
the
E
2
taps
in
the
100
%
position
,
and
with
the
current
at
5
amperes
and
voltage
at
120
volts
set
the
phase
shifter
so
that
the
phase
-
angle
meter
reads
300
(
i
.
e
.
,
current
lags
voltage
by
60
°
)
.
Now
set
the
voltage
on
studs
17
-
18
at
the
value
shown
in
Table
XI
(
under
ACCEPTANCE TESTS
)
for
the
relay
to
be
adjusted
,
and
adjust
R
3
so
that
the
MHO
unit
picks
up
at
20
±
2
%
amperes
for the
short
-
reach
relay
or
15
±
2
%
amperes
for
the
standard
-
reach
relay
.
c
.
Angle
of
Maximum
Torque
The
angle
of
maximum
torque
of the
MHO
unit
is
controlled
by
means
of
rheostat
R
4
.
Turning
the
R
4
screwdriver
adjustment
counterclockwise
increases
the
angle
of
maximum
torque
.
With
the
relay
connected
as
shown
in
Figure
10
and
the
E
2
taps
in
the
100
%
position
,
set
the
voltage
across
studs
17
-
18
at
40
volts
for the short
-
reach
relay
,
or
75
volts
for
the
standard
-
reach
relay
(
see
Table
XI
under
ACCEPTANCE
TESTS
)
.
Then
adjust
R
4
so
that
the
unit
picks
up
at
the
same
current
level
(
21
to
23
amps
for
the short
-
reach
relay
,
or
16.5
to
18.2
amps
for the
standard
-
reach
relay
)
at
phase
-
angle
meter
readings
of
330
°
and
270
°
.
(
See
MHO
unit
checks
in
the
section
on
ACCEPTANCE TESTS
)
.
27
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