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TESTING CURRENT DIFFERENTIAL RELAYS:
The CURRENT RELAY Test Screen is used to test current differential relays. The tests
are Pick Up (of the operational element), Timing, Slope (or differential characteristic),
and Instantaneous Pick Up. In addition, if the relay has harmonic restraint, a Harmonic
Restraint Test. Many electromechanical relays also have dc target and seal-in element
that need to be tested. Partial tests can be done using just one SR-98, Pick-up, Timing,
Instantaneous Pick Up and DC seal-in. To completely test current differential relays,
requires two SR-98 units operating together as Master / Slave, see
SELECTION OF
MASTER UNIT
for interface instructions.
The following tests, Pick Up, Timing, Instantaneous Pick Up and DC seal-in require only
one SR-98 to perform. From the
TEST MENU
Screen, select
CURRENT RELAY
. The
following test screen should be displayed.
Connect Relay Trip contacts to
STOP/MONITOR
terminals.
Note: If relay is solid state, microprocessor-based, or has a DC auxiliary relay that
requires a DC voltage prior to applying test currents, connect the appropriate relay
terminals to the
DC AUX
terminals. With the arrow key, highlight the
DC VOLTS
and
press the
DC
Button. Increase the DC voltage output by rotating the Control Knob until
proper voltage is applied.
Pickup Test:
Connect the appropriate
AC CURRENT MAIN
output terminals to the relay terminals so
that the test current will energize one Restraint Coil (Element) and the Current
Operating Coil (Element).
1.
With the arrow key, highlight
AC AMPERES
.
4. With
MODE SELECT
set to
MAINT.
(MAINTAIN), press the
INIT
button.
5.
Rotate Control Knob and increase current until the
TRIP
LED turns
ON
(and the
horn sounds, if the horn is set on).
Summary of Contents for SR-98
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