Motor - GE M60 Instruction Manual

5.6 GROUPED ELEMENTS
d) AMP UNBALANCE
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PATH: SETTINGS GROUPED ELEMENTS
 AMP UNBALANCE 1

This element receives current inputs from the source selected by the
setting. Generally, this element compares the ratio of motor negative sequence current (I_2) to the positive
LINE SOURCE
sequence current (I_1) times an adjustment factor to compensate for the actual motor load to a set threshold. The adjust-
ment factor is used to prevent nuisance alarms at light loads. If the motor is operating at an average current level equal to
5
or greater than the programmed full load current (FLA, as selected by the
setting) the adjustment factor is one. If the motor is operating at an average current level less than the programmed
AMPS
full load current (as selected by the
the ratio of average current to full load current. It is intended that the Amp Unbalance 1 element is used to generate an
alarm and Amp Unbalance 2 element is used to generate a trip.
A declaration of a "single-phasing" condition is made 2 seconds after the unbalanced current level exceeds 40%, or the
average current is above 25% of FLA and the current in any one phase is less than 2% of FLA
• AMP UNBAL 1(2) PICKUP: This setting selects the level of unbalanced current that generates a stage 1 (intended to
alarm) output. Note that a supply voltage unbalance of 1% creates a current unbalance of 6% in a typical three-phase
induction motor; a supply voltage unbalance of 2% creates a current unbalance of 12%. As a 2% voltage unbalance is
common in most applications, a setting of 0.15 is often used as the alarm level, and
to this level or higher.
• AMP UNBAL 1(2) PICKUP DELAY: The alarm delay is often set from 5 to 10 seconds. A higher level of unbalance will
cause motor stress in a shorter period; thus, a reasonable setting is 3 to 10 seconds.
• AMP UNBAL 1(2) RESET DELAY: This timer can be used to maintain the output until other equipment or an operator
can react to the unbalance condition.
5-132
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SETTING GROUP 1(6)
AMP UNBAL 1
FUNCTION: Disabled
AMP UNBAL 1 PICKUP:
MESSAGE
0.0%
AMP UNBAL 1 PICKUP
MESSAGE
DELAY: 0.00 s
AMP UNBAL 1 RESET
MESSAGE
DELAY: 0.00 s
AMP UNBAL 1 BLOCK:
MESSAGE
Off
AMP UNBAL 1 TARGET:
MESSAGE
Self-reset
AMP UNBAL 1 EVENTS:
MESSAGE
Disabled

SYSTEM SETUP
M60 Motor Protection System
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MOTOR

AMP UNBALANCE 1(2)
Range: Disabled, Enabled
Range: 0.0 to 100.0% in steps of 0.1
Range: 0.00 to 600.00 s in steps of 0.01
Range: 0.00 to 600.00 s in steps of 0.01
Range: FlexLogic™ operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
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SETTINGS
SYSTEM SETUP
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MOTOR MOTOR FULL LOAD AMPS
5 SETTINGS
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SYSTEM SETUP MOTOR
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MOTOR MOTOR FULL LOAD
setting) the adjustment factor is
is usually set
AMP UNBAL 1 PICKUP
GE Multilin
MOTOR