INSULATION RESISTANCE TEST
A test that may be run on all types of relays to determine the conditions of the insulation. In this test
1,000VDC is applied between relay connections that are brought to the outside of the relay and the frame of the
relay. It is of an infinite quality as read in the megohmeter, the cause is found and remedied.
A test that is conducted on any relay that has a time dial. The purpose is to determine the time dial reading
when the relay is fixed and moving contacts are closed by the manual rotation of the time dial toward zero. (Primary
ran or acceptance test or new test).
PICK UP TEST
A test conducted on relays to determine the minimum or maximum current, voltage, power or frequency that will
allow the relay operation and closure of the relay. In case of a time Overcurrent relay, its contacts should
eventually creep to a closed position with a magnitude of current introduced in its induction coil equal to the top
setting. The pick up test on a voltage relay is made in much the same manner.
TIME CHARACTERISTICS OR TIMING TEST
A test run to determine the elapsed time for relay operations with a specific abnormal quantity of current,
voltage, power or frequency. In the case of a time Overcurrent relay, one or more timing test are made at anywhere
from two to ten times the top setting to verify the time Overcurrent characteristics of the relay. One timing point
should be specified in the prescribed settings. Tests should be made with the relay in its panel and case and the
time test run at the calibration settings. A timing test should be made on most types of relays.
Some protective relays are instantaneous in operation or may have a separate instantaneous element. In this
context, the term instantaneous means having no intentional delay. If used, this specific pick up on the
instantaneous element should be set by test. An instantaneous element at two times pick up should operate
between 0.016 and 0.030 seconds.
TEST OF TARGET AND SEAL IN CIRCUIT
Most types of protective relays have a combination target and seal in unit. The target indicates that the relay
has operated. The seal in unit is adjustable to pick up at either 0.2 or 2.0 amperes. The setting for the seal in unit
must be specified with the relay settings.
*It should be verified by test that the contacts will seal in (hold in close position) with the minimum specified DC
current applied to the seal in unit.
TEST OF TRIPPING CIRCUIT
A test should be made, preferably at the time of the testing of the relays, to verify that operation of the relay
contacts will cause the breaker to trip.
The protective relays are one of the most important pieces of equipment in
your plants. The failure of the units to operate properly usually results in the loss
of major equipment and a larger period of down time.
A General Electric Over Current Relay being Tested and Calibrated in our repair shop, Southern
Substation can test and calibrate all of your relays we also can rebuild or supply you with replacement
relay's to fill all of your needs Please contact us for more information.
Relay testing Page two.