GE 869 Instruction Manual page 527

CHAPTER 4: SETPOINTS
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
HYSTERESIS
Range: 0.1 to 50.0% in steps of 0.1%
Default: 3.0%
This setting defines the pickup – drop out relation of the element by specifying the width
of the hysteresis loop as a percentage of the pickup value as shown above in the
Direction, Pickup, and Hysteresis setpoints figure.
RATE OF CHANGE TIME UNIT (dt)
Range: millisecond, second, minute
Default: milliseconds
This setting specifies the time base dt when programming the FlexElement as a rate of
change element.
The setting is applicable only if the Operating Mode is set to "Delta".
RATE OF CHANGE TIME
Range: 40 to 65535 in steps of 1
Default: 40
This setting specifies the duration of the time interval for the rate of change mode of
operation.
The setting is applicable only if the Operating Mode is set to "Delta".
PICKUP DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.000
This setting specifies the pickup delay of the element.
DROPOUT DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.000
This setting specifies the reset delay of the element.
EXAMPLES
13.8 kV power system:
• Phase VT Connection: Wye
• Phase VT Secondary: 66.4 V
• Phase VT Ratio: 120:1 (phase to neutral primary voltage = 120*66.4 = 7968 V)
• Aux VT Connection: Vab
• Aux VT Secondary: 115 V
• Aux VT Ratio: 120:1(phase-phase primary voltage = 13800V)
• Phase CTs Primary: 2000 A
• Ground CT Primary: 500 A
• Frequency: 60Hz
Detecting voltage difference:
The voltage difference between calculated phase-phase voltage derived from Wye
connected phase VTs, and the directly measured phase-phase voltage from auxiliary VT
can be monitored by programming a FlexElement.
FlexElement settings:
• Input 1(+): J2 Vab RMS
• Input 2 (-): J2 Vaux RMS (input from VT connected between phases A and B)
• Operating Mode: Absolute
• Input Comparison Mode: Level
• Direction: Over
FLEXLOGIC
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