Manual 37353A
MFR 13 Packages - Protection Relay
Page 44/91
© Woodward
Voltage Asymmetry Monitoring
The phase-phase voltages are monitored.
Function
"Voltage asymmetry not within permissible limits"
The monitored phase-phase voltage differential in the three phases is not within the configured permissible limits
for asymmetry (asymmetric voltage vectors; the threshold corresponding to the differential value). The alarm
message "
Asymmetry
" will be displayed. This message can
be suppressed with the discrete input "Blocking of
protective functions / remote acknowledgement".
Asymmetry-
Monitoring ON
Asymmetry monitoring
ON/OFF
ON
................Voltage asymmetry monitoring is enabled. The subsequent screens of
this function are displayed.
OFF
..............Voltage asymmetry monitoring is disabled. The subsequent screens
of this function are not displayed.
Asymmetry
Response v. 00V.
Maximum permissible asymmetry
0 to 99 V
The maximum voltage asymmetry is defined by this parameter. If this limit is
reached or exceeded, the unit outputs the message "
Asymmetry
". If a relay was
assigned to this function in the relay manager, that relay will be energized.
Asymmetry
Delay 00.00s
Pickup delay
0.02 to 99.98 s
In order to initiate a voltage asymmetry alarm, the measured voltage differential
must rise above and remain above the configured threshold without interruption for
at least the period of time specified in this screen.
Asymmetry
Hysteresis 00V
Hysteresis for the asymmetry monitoring
0 to 99 V
In order to prevent system fluctuations from continually initiating a voltage asym-
metry fault, a lower release point is defined here. If the control monitors the voltage
asymmetry beyond the permissible limit, the voltage differential must fall below
that threshold plus the voltage level defined here for the fault condition to be rec-
ognized as no longer existing.