*
*
GEH-1793
The AC voltage or DC current relays are adjusted to pick up at 70-80 percent of
rating at rated frequency.
The DC voltage relays are adjusted to pick up at 50-60
percent of rating when cold.
After AC relays have been continuously energized for a few hours (minimum four
hours) at rated voltage, the pickup and dropout voltages increase by 3. 5 to 7. 5
percent.
For DC relays, the pickup and dropout voltages increase by 5 to 10
percent.
The wipe on HGA11 relays exerts a contact pressure of 35 grams
�
10 percent on
11 a" contacts and 10 grams
�
10 percent on 11b" contacts.
C ONS TR U CTION
The HGA11 is a molded case relay.
The various parts of the relay can be seen
in Figure 10.
The control spring is used for adjusting the pickup and dropout
voltage.
The function of the voltage barrier is to avoid flashover between a pair
of electrically separate, but mechanically coupled normally closed contacts, or
between a pair of normally open contacts. Cover spring clips maintain spring force
against the cover to hold the cover in position.
RECEIVIN G, HANDLIN G AND S TORA G E
These relays, when not included as 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 damage sustained in transit.
If 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 damaged nor the adjustments disturbed.
If the relays are not to be installed immediately, store them in their original
cartons in a place that is free from moisture, dust and metallic chips.
Foreign
matter that collects on the outside of the case could get inside when the cover is
removed, and cause trouble when operating the relay.
P ERIODIC C HECKS AND RO UTINE MAINTENANCE
In view of the vital role of relays in the operation of a power system, it is
important that a periodic test program be followed.
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 requirements, the points listed
under
ACCEP TANCE TESTS
should be checked at an interval of from one to two years.
*Indicates Revision
7
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