GEK-86105
PERIODIC CHECKS AND ROUTINE MAINTENAN C E
Protective rel ays pl ay a vital rol e in the operation of a power system, and it is
important to foll ow a periodic test program.
The interval between periodic checks
wil l vary depending upon environment, type of relay and the user's experience with
periodic testing.
Until the user has accumul ated enough experience to select the
test interval best suited to his individual requirements, the points l isted
in
the
ACCEPTANCE TEST S
section should be checked at an interval of from one to two years .
Operate the disk and shaft assembl y b y hand.
Check that the contacts are making
with the proper wipe.
Al l ow the disk to reset, then check that there is no sign of
excessive friction or a tendency to bind.
Check for obstructions to disk travel .
Dirt or metal l ic particl es in the watt-metric or d rag magnet gaps can interfere with
the motion of the disk.
Examine contact sur faces for tarnishing or cor rosion.
Fine sil ver contacts shoul d
not be cl eaned with knives, fil es , or abrasive paper or cl oth.
Knives or files may
1
eave sc ratches which increase arcing and deteri oration of the contacts.
Ab ras ive
paper or cloth may l eave minute particl es of insul ating abrasive material in the
contacts and thus prevent cl osing.
Use a burnishing tool specifical ly des igned for
this purpose.
SERVICING
Induction unit pickup for any current tap
is
adjusted by a spring adjusting ring.
If the adjustment has been disturbed, turn the ring by inserting a screw driver in
the notches around the edge; turning the ring b rings the operating current of the
unit into agreement with the tap setting.
This adjustment al so makes any setting
between the various tap s ettings possibl e.
Note, however, that if pickup is changed
by
turning the spring adjusting ring, then the rel ay wil l be operating at a
different
torque level,
and the published time curves wil l not apply for this
setting.
The unit has been factory adjusted to close its contacts f rom any time dial position
at minimum current within
5%
of the tap plug setting.
If
a
pickup time for
a
particular time dial setting and pickup
mul tipl e is outside the limits mentioned in
the acceptance
tests.
changing the position
of
the drag magnet
on its supporting
shelf will restore the pickup time.
Moving the magnet towards the
sha ft decreases
the pickup
t i
m
e
,
while
moving it
away
from t
h
e shaft
increas es the pickup time.
I
f
the drag magnet
is
moved towards the shaft, be sure
that it clears
the
counterweight
on
the
d
i
s
k
for all positions of
the disk
and shaft assembl y in its final position.
V/hen the magnet is moved away f rom the s
h
a f
t
,
its
outer edge must
be
at l east
l/8
inch from the edge of the disk at the disk's smallest radius.
Pickup
and ti
me tests shoul d always be made with the rel ay in its case s o that the
magnetic effect of the cas� is the same as when the rel ay is in service.
RENEWAl PART S
Sufficient quantities of renewal parts shoul d be kept in �tock for the
prompt
replacement
of any that are worn, broken or damaged.
When orde ring renewal parts ,
address
t
h
e nearest Sales
O
f
f
i
c
e of
the General
Electric
C
om
pa
ny
.
Specify
the name
of the
part wanted, quantity required, and
co
m
pl
e
te nameplate
data,
i
n c
l
u
d
i
n
g
the serial number, of the
relay.
1 4
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