Manual 37143A
MFR 15 - Protection Relay & Control
Page 74/119
© Woodward
Unbalanced Load Monitoring (
Option PS
)
NOTE
All percentage values refer to a percentage of the configured rated power (page 44).
Function:
"Unbalanced load not within the permissible range"
The percentage threshold value indicates the permissible variation of phase current from the arithmetic mean
value of all three-phase currents. If the measured value is greater than the threshold, the message "
Unbalance
"
appears. This message can be suppressed with the discrete input "Blocking of protective device / remote ac-
knowledgement".
Unbalanced load
Monitoring ON
Unbalanced load monitoring
ON/OFF
ON
................Unbalanced load monitoring is enabled. The subsequent screens of
this function are displayed.
OFF
..............Unbalanced load monitoring is disabled. The subsequent screens of
this function are not displayed.
Unbalanced load
Response v. 000%
Maximum permissible unbalanced load
0 to 100 %
The maximum unbalanced load refers to the measured three-phase currents. If an
asymmetrical load causes the phase currents to exceed the configured percentage
for the configured time, the unit displays the alarm message "
Unbalance
". If a
relay was assigned to this function in the relay manager, that relay will be ener-
gized.
Unbalanced load
Delay 00.00s
Pickup delay
0.02 to 99.98 s
In order to initiate an unbalanced load alarm, the measured active load must exceed
and remain above the configured differential threshold without interruption for at
least the period of time specified in this screen.
Unbalanced load
Hysteresis 00%
Hysteresis for the unbalanced load monitoring
1 to 20 %
In order to prevent system fluctuations from continually initiating unbalanced load
alarms, a lower release point is defined here. If the control monitors the active load
above the permissible differential limit, the load must drop below the load differen-
tial percentage defined here for the fault condition to be recognized as no longer
existing.