Manual 37143A
MFR 15 - Protection Relay & Control
Page 64/119
© Woodward
Undervoltage Monitoring (
Option U
)
Function
: "Voltage not within permissible limits"
The monitored voltage in at least one phase is not within the configured permissible limits for undervoltage. The
alarm message "
Und.volt.1
" or "
Und.volt.2
" will be displayed. This message
cannot
be suppressed with
the discrete input "Blocking of protective functions / remote acknowledgement".
Undervoltage
Monitoring ON
Undervoltage monitoring
ON/OFF
ON
................Undervoltage monitoring is enabled. The subsequent screens of this
function are displayed.
OFF
..............Undervoltage monitoring is disabled. The subsequent screens of this
function are not displayed.
Screen for
Phase-neutral
:
Undervoltage 1
(Phase-N) <000V
Screen for
Phase to phase
:
Undervoltage 1
V(ph-ph) <000V
Threshold
(Phase-phase) [1] 20 to 150 V; [4] 20 to 520 V
undervoltage level 1
(Phase-neutral) [1] 10 to 87 V; [4] 10 to 300 V
Undervoltage (level 1) is defined by this parameter. If this limit is reached or fallen
below, the unit outputs the message "
Und.volt.1
". If a relay was assigned to
this function in the relay manager, that relay will be energized.
Undervoltage 1
Delay 00.00s
Pickup delay, level 1
0.02 to 99.98 s
In order to initiate an undervoltage (level 1) alarm, the measured voltage must fall
below and remain below the configured threshold without interruption for at least
the period of time specified in this screen.
Screen for
Phase-neutral
:
Undervoltage 2
(Phase-N) <000V
Screen for
Phase to phase
:
Undervoltage 2
V(ph-ph) <000V
Threshold
(Phase-phase) [1] 20 to 150 V; [4] 20 to 520 V
undervoltage level 2
(Phase-neutral) [1] 10 to 87 V; [4] 10 to 300 V
Undervoltage (level 2) is defined by this parameter. If this limit is reached or fallen
below, the unit outputs the message "
Und.volt.2
". If a relay was assigned to
this function in the relay manager, that relay will be energized.
Undervoltage 2
Delay 00.00s
Pickup delay, level 2
0.02 to 99.98 s
In order to initiate an undervoltage (level 2) alarm, the measured voltage must fall
below and remain below the configured threshold without interruption for at least
the period of time specified in this screen.
Undervoltage
Hysteresis 00V
Hysteresis for the undervoltage monitoring, level 1 + 2
0 to 99 V
In order to prevent system fluctuations from continually initiating undervoltage
alarms (both levels), a higher release point is defined here. If the control monitors
the voltage below the permissible limit, the voltage must rise above that threshold
and the voltage level defined here for the fault condition to be recognized as no
longer existing.
Example: If a 480 V system has an undervoltage limit of 440 V and a hysteresis of
10 V, the monitored voltage for an overvoltage alarm must rise above 450 V to re-
set the alarm.