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GEI-12083
RECEIVING, HANDLING AND STORAGE
These relays, when not included as a part of a control panel, will be shipped in cartons designed to
protect them against damage.
Immediately upon receipt of a relay, examine it for any damage sustained in
transit.
If injury or damage resulting from rough handling is evident, file a damage claim at once with
the transportation company and promptly notify the nearest General Electric Apparatus Sales Office.
Reasonable care should be exercised in unpacking the relay in order that none of the parts are injured
or the adjustments disturbed.
If the relays are not to be installed immediately, they should be stored in their original cartons
in a place that is free from moisture, dust and metallic chips.
Foreign matter collected on the outside
of the case may find its way inside when the cover is removed and cause trouble in the operation of the
relay.
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 under INSTALLATION PROCEDURE be checked at an interval of
from one to two years.
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 rapidly.
Its
flexibility insures the cleaning of the actual points of contact.
Do not use knives, files, abrasive paper
or cloth of any kind to clean relay contacts.
POWER REQUIREMENTS - GENERAL
All alternating current operated devices are affected by frequency.
Since non-sinusoidal waveforms
can be analyzed as a fundamental frequency plus harmonics of the fundamental frequency, it follows that
alternating current devices (relays) will be affected by the applied waveform.
Therefore, in order to properly test alternating current relays it is essential to use a sine wave
of current and/or voltage.
The purity of the sine wave (i.e., its freedom from harmonics) cannot be ex-
pressed as a finite number for any particular relay; however, any relay using tuned circuits, R-L or RC
networks, or saturating electromagnets (such as time-overcurrent relays) would be essentially affected
by non-sinusoidal wave forms.
Similarly, relays requiring d-ccontrol power should be tested usingd-c and not full wave rectified
power.
Unless the rectified supply is well filtered, many relays will not operate properly due to the
dips in the rectified power.
Zener diodes, for example. can turn off during these dips.
As a general
rule, the d-c source should not contain more than 5 percent ripple.
ELECTRICAL TESTS
DRAWOUT RELAYS GENERAL
Since all drawout relays in service operate in their cases,it is recommended that they be tested in
their cases or an equivalent steel case.
In this way any magnetic effects of the enclosure will be ac-
curately duplicated during testing.
A relay may be tested without removing it from the panel by using a
12XLA13A test plug.
This plug makes connections only with the relay and does not disturb any shorting
bars in the cases. Of course, the 12XLA12A test plug may also be used.
Although this test plug allows
greater testing flexibility, it also requires C T shorting jumpers and the exercise of greater care since
connections are made to both the relay and the external circuitry.
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