GE M60 Instruction Manual page 323

CHAPTER 5: SETTINGS
Two underpower elements are provided.
The underpower function uses the source selected by the
currents and voltages must be configured on that source, otherwise the underpower function is not functional. The
underpower element responds to total three-phase apparent power measured from the phase current and voltages.
When the underpower element is enabled, a trip or alarm is initiated once the magnitude of three-phase apparent power
falls below the pickup level for a period of time specified by the delay. For example, underpower can be used to detect
loss-of-load conditions. Loss of load conditions do not always cause a significant loss of current. Power is a more accurate
representation of loading and can be used for more sensitive detection of load loss or pump cavitations. This can be
especially useful for detecting process related problems.
UNDERPOWER 1 START BLOCK DELAY
motor is starting. If not in the starting state, the motor status is indicated by the
setup section under the
SETTINGS  SYSTEM SETUP  MOTOR
operand for state determination.
OFFLINE
The underpower element is active only when the motor is running and is blocked upon the initiation of a motor start for a
period of time specified by this setting. For example, this block can be used to allow pumps to build up head before the
underpower element trips or alarms. A value of 0 specifies that the feature is not blocked from start. For values other than
0, the feature is disabled when the motor is stopped and also from the time a start is detected until the time entered
expires.
UNDERPOWER 1 ALARM PWR PICKUP
quantity is 3 × VT pu base × CT pu base per source selected as a motor line source. Set it less than the motor load current
during normal operations.
UNDERPOWER 1 ALARM PICKUP DLY
any short lowering of the current (for example, during system faults).
UNDERPOWER 1 TRIP PWR PICKUP
power on primary side, which is calculated as
delta connected VTs, and as 3 x Phase CT Primary x Phase VT Ratio x Phase VT Secondary in case of wye connected VTs.
Set this setting less than the corresponding setting for the alarm stage.
UNDERPOWER 1 TRIP PICKUP DLY
short lowering of the current (for example, during system faults).
UNDERPOWER 1 TRIP RESET DLY
breaker or contactor to disconnect the motor.
— This setting specifies an operand used to block the underpower function. A panel cutoff switch or
UNDERPOWER 1 BLOCK
other user specified condition typically is used to block the function.
M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
UNDERPOWER 1 BLOCK:

Off
UNDERPOWER 1 TARGET:

Self-reset
UNDERPOWER 1 EVENTS:

Disabled
SYSTEM SETUP  MOTOR  MOTOR LINE SOURCE
— This setting specifies the length of time to block the underpower function when the
— This setting specifies a pickup threshold for the alarm stage. The base per-unit power
— This setting specifies a time delay for the alarm stage. Set it long enough to overcome
— This setting specifies a pickup threshold for the trip stage. The base quantity is 3-phase
√
3 x Phase CT Primary x Phase VT Ratio x Phase VT Secondary in case of
— This setting specifies a time delay for the trip stage. Set it long enough to overcome any
— This setting specifies a time delay to reset the trip command. Set it long enough to allow
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Enabled, Disabled
MOTOR OFFLINE
menu for additional information on using the
GROUPED ELEMENTS
setting. Phase
operand. See the Motor
MOTOR
5-195
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