Quantcast Figure 113. Typical test connections for a differential relay

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TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
Figure 11-2. Typical test connections for directional overcurrent relays
a. Advance field testing preparation. Study sys-
tem protection, including station single lines and
relay instruction books. Obtain and review previous
tests and arrange to have all required test equip-
ment. Check that outage requests, switching ar-
rangements, and any remote operations have been
b. Field test equipment. The test equipment for
field testing must be portable, so tests can be made
at the relay panel. For most of the common relays,
the following will be needed: a variable voltage
115 VOLTS , 60
autotransformer, a multirange ac and dc voltmeter,
a multirange ac and dc ammeter, an ohmmeter,
Figure 113. Typical test connections for a differential relay
auxiliary current transformers, a timer, a three-
phase shifter, and auxiliary relays. Test plugs,
shows a typical test connection for reactance relays.
leads, noninductive resistors, and a relay tool kit
Substitute a resistor for the reactor when checking
will also be required. In general, most laboratory
the polarity of impedance distance relays.
test equipment is portable and can be used in the
d. Pilot wire relays. Test the relay for minimum
field. Test instruments are available in prepackaged
pickup, operating time, and restraint torque. Check
test sets. The use of these sets simplifies testing.
the circuits for continuity and reversed connections.
c. Laboratory testing. If the field testing indicates
An overall test should be made to check the com-
that a relay needs a shop repair, then engineering
plete installation, including the pilot circuits and
evaluation is necessary in determining what effect
external devices associated with the installation.
its removal will have on the reliability of the protec-
For test connections, see figure 11-5.
tive system. Short time removals of one phase of
e. Synchronism check relays. Check the timing,
three-phase protective items, switching to alternate
polarity, and phase angle (closing).
power sources, or a replacement relay with correct
f. Reclosing relays. Check the complete timing
settings may be necessary. Such judgment should be
and reclosing sequence. Test initial and delayed
made as a part of the advance field testing prepara-
reclosures and observe switches and moving parts.
g. Plunger and hinged armature relays. Check
d. Laboratory test equipment. Some of the com-
the relay pickup and drop-out values by gradually
mon test equipment that should be available in a
increasing or decreasing the operating current or
laboratory for servicing relays is shown in table
11-l. In addition to these devices, a relay tool kit,
h. Thermal relays. Test for thermal pickup cur-
test plugs, test leads, printed circuit board extend-
rent with the relay hot and check the pickup of the
ers, a frequency generator, ac and dc power sup-
instantaneous unit.
plies, a portable test unit, an oscillograph, a power
amplifier, and special equipment testers, as re-
11-8. Relay test equipment.
quired for certain types of relays, will be needed.
When selecting types and outputs of test equip-
Before testing minimize potential trouble by ad-
ment, consideration should be given to the various
vance preparation.


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