GEI-44233
INSPECTION
At the time of installation, the relay should be inspected for tarnished contacts, loose screws, or
other
imperfections.
If any trouble is found, it should be corrected in the manner described under
MAINTENANCE.
CAUTION:
EVERY CIRCUIT IN THE DRAWOUT CASE HAS AN AUXILIARY BRUSH. IT IS ESPECIALLY IMPORTANT ON CURRENT
CIRCUITS AND OTHER CIRCUITS WITH SHORTING BARS THAT THE AUXILIARY BRUSH BE BENT HIGH ENOUGH TO ENGAGE THE
CONNECTING PLUG OR TEST PLUG BEFORE THE MAIN BRUSHES DO.
THIS WILL PREVENT CT SECONDARY CIRCUITS FROM BEING
OPENED.
PERIODIC CHECKS AND ROUTINE MAINTENANCE
In view
of the vital role of protective relays in
the operation of a power system, it is important
that a
periodic test program be followed.
It is recognized that the interval between periodic checks
will
vary depending
upon
environment, type of relay and the user's experience with periodic testing.
Until the
user
has accumulated enough experience to select the test interval best suited to his individual require
ments, it is
suggested that the points listed below be checked at an interval
of
once a year.*
These tests are intended to ensure that the relays have
not
de
v
ia
te
d from their original settings.
If
deviations are en
c
ounte
r
e
d, the relay must be retested and serviced as d
es
c
r
ib
e
d
in
this manual.
TIME-OVERCURRENT
UNIT
Perform the tests described in the
ACCEPTANCE
TEST section. The tap that i
s in
service
may be used
instead of the lowest tap; this will not change
the
test limits.
INSTANTANEOUS
UNIT
Check that the instantaneous unit
picks up at the desired current level,
as
o
ut
l
i
ne
d
in the ACCEPTANCE
TEST section.
If the unit is not set at the minimum
calibration mark,
pickup should be
within
+1 5
pe
rc
en
t
of
the mark for which it is set.
HIGH DROPOUT
INSTANTANEOUS
UNIT
Check pickup and dropout current to the limits outlined in the
ACCEPTANCE TE
ST section.
TARGET AND SEAL-IN
UNIT
Check pickup and dropout as outlined in the ACCEPTANCE TEST section.
CONTACT CLEANING
For cleaning relay contacts, a flexible burnishing
tool should
be used. This consists of a flexible
strip of metal with an etched-roughened surface resembling in effect a superfine file. The polishing action
is so delicate that no scratches are left, yet it
will
clean off any corrosion thoroughly and
r
apidl
y
.
Its
flexibility ensures the cleaning of the actual points of contact.
Do not use knives, files, abrasive paper
or cloth of any kind to clean relay contacts.
SYSTEM TEST
Although this instruction book is primarily
written to check and set the lAC
rel
ay
, overall functional
tests to check tne system operation are recommended at intervals based on the customer's experience.
SERVICING AND ADJUSTMENTS
TIME-OVERCURRENT UNIT
If
it is found during installation or
p
e
r
iodi
c testing
that
t
h
e time-overcurrent unit is out of limits,
the unit may be recalibrated a
s
f
ol
l
o
w
s
:
Rotate time dial
to
No. 0
time-dial setting and check by means of a
lamp that
the contacts just close.
Where the contacts
just
close
can be
adjusted by
running t
he stationary contact brush in or out by
means
of
its adjusting screw. This
s
c
rew
s
ho
u
l
d
b
e
h
e
l
d secu
rely
in its sup
p
or
t
.
With the contacts just closing at
No. 0
time setting, there should
be
sufficient gap between the
stationary contact brush and
its metal b
a
c
k
in
g
strip
to ensure approximately l/32
inch
wipe.
*
Indicates revision
8
www
. ElectricalPartManuals
. com
