Operation Manual 37107F
MFR 3 - Multi Function Relay
Page 108/165
© Woodward
Generator Underfrequency Monitoring
The monitoring of the frequency is carried out at two levels. The measurement of the frequency encompasses all
three phases if all voltages are greater than 15 % of the rated value (100 Vac or 400 Vac). This enables a very
rapid and precise frequency measurement. The frequency, however, is also correctly detected if voltage in only
one phase is present.
Function: "
Generator frequency not within the permissible range"
A fault condition is recognized if the frequency of the generator is outside of the limit values configured for un-
derfrequency. The enabling of generator underfrequency monitoring is delayed via "Delayed monitoring" in or-
der to enable correct generator start-up. An alarm is issued if a fault condition is detected.
NOTE
Energizing terminal 6 ("monitoring") enables this monitoring.
Parameter
158
Gen.underfreq.
monitoring ON
Generator underfrequency
ON/OFF
ON
................ Generator underfrequency monitoring is enabled. The subsequent
screens of this function are displayed.
OFF
.............. Generator underfrequency monitoring is not performed. The subse-
quent screens of this function are not displayed.
Parameter
159
Gen.underfreq. 1
f > 00.00Hz
Generator underfrequency: limit 1
40.00 to 85.00 Hz
The value for underfrequency limit 1 is configured in this screen. If the monitored
frequency reaches or falls below this level for the configured delay time, the unit
issues an alarm and opens the GCB.
Tripping of class F3 alarm
Parameter
160
Gen.underfreq. 1
Delay 00.00s
Generator underfrequency: delay 1
0.02 to 99.98 s
The generator underfrequency monitoring threshold limit 1 must be exceeded,
without interruption, for the time period configured here before the configured re-
lay will be energized.
Parameter
161
Gen.underfreq. 2
f > 00.00Hz
Generator underfrequency: limit 2
40.00 to 85.00 Hz
The value for underfrequency limit 2 is configured in this screen. If the monitored
frequency reaches or falls below this level for the configured delay time, the unit
issues an alarm and opens the GCB.
Tripping of class F3 alarm
Parameter
162
Gen.underfreq. 2
Delay 00.00s
Generator underfrequency: delay 2
0.02 to 99.98 s
The generator underfrequency monitoring threshold limit 1 must be exceeded,
without interruption, for the time period configured here before the configured re-
lay will be energized.