GE M60 Instruction Manual page 273

5 SETTINGS
If the undercurrent function is enabled, a trip or alarm is initiated once the IA, IB or IC current magnitude falls below the
pickup level for a time specified by the delay setting For example, the undercurrent element may be used to detect loss-of-
load conditions. This may be especially useful for detecting process related problems.
The undercurrent element is active when the motor is running at speed 1; that is, when the motor status is running and
speed 2 is not employed or active.
• UNDERCURRENT START BLOCK DLY: This setting specifies the length of time to block the undercurrent function
when motor is starting. If not in the starting state, the motor status is indicated by the
to the Motor setup section for additional information on using the
The undercurrent 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 delay may be used to allow pumps to build up head
before the undercurrent 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.
• UNDERCURRENT ALARM PICKUP: This setting specifies a pickup threshold for the alarm stage. The alarm pickup
threshold should be less than the motor load current during normal operations.
• UNDERCURRENT ALARM PICKUP DLY: This setting specifies a time delay for the alarm stage. The time delay
should long enough to overcome any short lowering of the current (for example, during system faults).
• UNDERCURRENT TRIP PICKUP: This setting specifies a pickup threshold for the trip stage. This setting should be
less than the corresponding setting for the alarm stage.
• UNDERCURRENT TRIP PICKUP DLY: This setting specifies a time delay for the trip stage. This time delay should be
long enough to overcome any short lowering of the current (for example, during system faults).
• UNDERCURRENT TRIP RESET DLY: This setting specifies a time delay to reset the trip command. This delay should
be set long enough to allow breaker or contactor to disconnect the motor.
• UNDERCURRENT BLOCK: This setting specifies an operand used to block the undercurrent function. A panel cutoff
switch or other user specified condition is typically used to block the function.
SETTINGS
UNDERCURRENT
FUNCTION
= Enabled
UNDERCURRENT BLOCK
AND
= Off
SETTINGS
UNDERCURRENT START
BLOCK DLY
FLEXLOGIC OPERAND
T
PKP
MOTOR OFFLINE
MOTOR STATUS
Running at speed 1
SETTING
MOTOR LINE SOURCE
= Ia
= Ib
= Ic
GE Multilin
MOTOR OFFLINE
AND
SETTING
0
UNDERCURRENT ALARM
PICKUP
RUN
magnitude Ia < PICKUP
magnitude Ib < PICKUP
magnitude IC < PICKUP
SETTING
UNDERCURRENT TRIP
PICKUP
RUN
magnitude Ia < PICKUP
magnitude Ib < PICKUP
magnitude IC < PICKUP
Figure 5–66: UNDERCURRENT LOGIC
M60 Motor Protection System
5.6 GROUPED ELEMENTS
MOTOR OFFLINE
operand for state determination.
SETTINGS
UNDERCURRENT ALARM
PICKUP DLY
UNDERCURRENT TRIP
PICKUP DLY
UNDERCURRENT TRIP
RESET DLY
T
PKP
OR
0
T
PKP
T
RST
OR
operand. Refer
5
FLEXLOGIC OPERAND
U/CURR ALARM OP
FLEXLOGIC OPERAND
U/CURR TRIP OP
FLEXLOGIC OPERANDS
U/CURR ALARM PKP
U/CURR TRIP PKP
833024A1.CDR
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