61
TESTING PHASE SEQUENCE UNDERVOLTAGE RELAYS:
This type of relay is tested using the
SYNCH RELAY
Test Screen.
This generic procedure is for a three-phase induction disk relay used to protect ac
machines for under-voltage or phase reversal, which may be tested using an open-delta
test potential. Similar relays can be tested using the same basic procedure. For relay
specific test guides relative to testing these types of relays, see the Megger web site at
avointl.com
. Click on Products, Relay Test Equipment then on Application Guides.
Type of Tests
Pick up High Voltage Contacts
Pick up Low Voltage Contacts
Timing High Voltage Contacts
Timing Low Voltage Contacts
Loss of Phase
Phase Sequence
Always refer to the manufacturers literature before testing the relay
Reverse Phase Voltage Relay:
The SYNCH RELAY Test Screen is used to test reverse phase voltage relays, which
can be tested using an Open-Delta test potential. This procedure applies to relays that
require a balanced three-phase delta voltage. This voltage will be developed using the
230 V / 4 A
CURRENT MAIN
output terminal, with common, and the
AC AUX, 300 V /
0.25 A
output terminals. The measured output voltages are labeled
(M)
for the
230 V
CURRENT MAIN
and
(AUX)
for the
AC AUX
output. The phase angle between the two
voltages is displayed as
φ
Vm lags V,
where
Vm
is the
(M)
output and the other voltage
V
is from the
AC AUX
output. To create an open-delta voltage the
AC AUX
voltage will
be used as the zero reference voltage and the
230 V
Main
voltage will be phase shifted
to an angle of 300 degrees lagging (60 degrees leading the AC AUX voltage). This will
appear to the relay as a balanced three-phase delta voltage.
From the
TEST MENU
Screen, select
SYNCH RELAY
. The following test screen should
Summary of Contents for SR-98
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