GE GCX51A - Mechanical Inspection; Control Spring Adjustment; Electrical Checks; MHO Unit Checks

GEI
-
98328
Mechanical
Inspection
It
is
recommended
that the
following
mechanical
adjustments
be
checked
:
1
.
MHO
UNIT
5
-
8
mils
OHM
UNIT
CHECK
POINTS
b
-
8
mi
Is
Kotating
shaft
end
play
120
-
130
mils
35
-
45
mils
Contact
gap
3
-
5
mils
3
-
5
mils
Contact
wipe
There
should be
no
noticeable
friction
in
the
rotating
structure
of
the
OHM
and
MHO
units
.
2
.
Make
sure
control
springs
are
not
deformed
and
spring
convolutions
do
not
touch
each
other
.
3
.
With
the
relay
well leveled
in
its
upright
position
,
the
OHM
unit
and
MHO
unit
contacts
must
be
open
.
The
moving
contacts
of the
OHM
and
MHO
units
should
rest
against
their
backstops
.
The
armature
and
contacts
of the
seal
-
in
unit
should
move
freely
when
operated
by
hand
.
There should
be
at
least
1
/
32
"
wipe
on
the
seal
-
in
contacts
.
4
.
5
.
Make
sure
the
armature
of the
telephone
-
type
relay
(
OX
)
is
moving
freely
.
Check
the
location
of the
contact
brushes
on
the cradle
and
case
blocks
against
the
internal
connection
diagram
for
the
relay
.
6
.
7
.
Electrical
Checks
Before
any
electrical
checks
are
made
on
the
OHM
and
MHO
units
,
the
relay
should
be connected
as
shown
in
Figure
10
and be
allowed
to
warm
up
for
approximately
15
minutes
with
the
potential
circuit
alone
(
studs
17
-
18
)
energized
at
rated
voltage
and
with
the
E
2
and
No
.
1
taps
set
at
100
%
.
The
units
were
warmed
up
prior
to
factory
adjustment
and
if
rechecked
when
cold
will
tend
to
underreach
by
3
%
or
4
%
.
Accurately
calibrated
meters
are
of
course
essential
.
It
is desirable
to
check
the
factory
settings
and
calibrations
by
means
of
the
tests
described
in
the
following
sections
.
The
OHM
and
MHO
units
were
carefully
adjusted
at
the
factory
and
it
is
not
advisable
to
disturb
these
settings
unless
the
following
checks
indicate
conclusively
that
the
settings
have been
disturbed
.
If
readjustments
are
necessary
,
refer
to
the
section
on
SERVICING
for
the
recommended
procedures
.
MHO
Unit
Checks
a
.
Control
Spring
Adjustment
Connect
the
relay
as
shown
in
Figure
10
and
set
the
E
^
tap
leads
at
100
%
.
The
position
of
the
No
.
1
and
No
.
2
tap
leads does
not
affect
this
test
.
Make
sure
that the
relay
is
level
in
its
upright
position
.
16
Courtesy of NationalSwitchgear.com