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369 MOTOR MANAGEMENT RELAY – QUICKSTART GUIDE
S8 POWER ELEMENTS
CHAPTER 4: KEYPAD SETPOINTS
4.6.6
Underpower
PATH: S8 POWER ELEMENTS
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UNDERPOWER
If enabled, a trip or alarm occurs when the magnitude of three-phase total real power falls
below the pickup level for a period of time specified by the delay. The underpower element
is active only when the motor is running and will be blocked upon the initiation of a motor
start for a period of time defined by the
BLOCK UNDERPOWER FROM START
setpoint (e.g.
this block may be used to allow pumps to build up head before the underpower element
trips or alarms). A value of 0 means the feature is not blocked from start; otherwise the
feature is disabled when the motor is stopped and also from the time a start is detected
until the time entered expires. The pickup level should be set lower than motor loading
during normal operations.
Underpower may be used to detect loss of load conditions. Loss of load conditions will not
always cause a significant loss of current. Power is a more accurate representation of
loading and may be used for more sensitive detection of load loss or pump cavitation. This
may be especially useful for detecting process related problems.
UNDERPOWER
BLOCK UNDERPOWER
FROM START: 1 s
Range: 0 to 15000 s in steps of 1
UNDERPOWER
ALARM: Off
Range: Off, Latched, Unlatched
ASSIGN ALARM RELAYS:
Alarm
Range: None, Alarm, Aux1, Aux2 or combinations
UNDERPOWER ALARM
LEVEL: 2 kW
Range: 1 to 25000 kW in steps of 1
UNDERPOWER
ALARM DELAY: 1 s
Range: 0.5 to 255.0 s in steps of 0.5
UNDERPOWER
ALARM EVENTS: Off
Range: Off, On
UNDERPOWER
TRIP: Off
Range: Off, Latched, Unlatched
ASSIGN TRIP RELAYS:
Trip
Range: None, Trip, Aux1, Aux2, or combinations
UNDERPOWER TRIP
LEVEL: 1 kW
Range: 1 to 25000 kW in steps of 1
UNDERPOWER
TRIP DELAY: 1 s
Range: 0.5 to 255.0 s in steps of 0.5
