Motor - GE 869 Instruction Manual

CHAPTER 4: SETPOINTS
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Motor

Setup
NOTE:
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
detected from the three-phase voltage inputs is declared invalid. The switching is not
performed if the frequency from the alternative reference signal is detected invalid.
• Upon detecting valid frequency on the main frequency and phase reference signal,
tracking is switched back to that reference.
FREQUENCY TRACKING should be set to "Disabled" only under very unusual circumstances.
Consult the factory for special variable-frequency applications.
The following settings reflect the design and configuration of the motor that the relay will
protect. Note that some protection elements are dependent on these settings for correct
operation.
Path:
Setpoints > System > Motor > Setup
MOTOR FULL LOAD AMPS (FLA)
Range: 1 to 5000 A in steps of 1 A
Default: 100 A
This setting represents the full load current (FLA) of the motor. FLA is a standard motor
parameter that can be found on the motor nameplate.
MOTOR OVERLOAD FACTOR
Range: 1.00 to 1.50 in steps of 0.01
Default: 1.00
This setting defines the current level at which the motor is considered to be overloaded.
If the motor current exceeds the Motor Overload Factor threshold, the 869 Thermal
Model reacts by accumulating thermal capacity. Normally, this factor is set slightly
above the motor service factor to account for inherent load measuring errors (CTs and
limited relay accuracy). The typical total inaccuracy factor is 8 to 10%; as such, for
motors with a thermal capability at a rated service factor of 1 or 1.15, the Motor
Overload Factor must be set to 1.1 or 1.25 respectively.
MOTOR NAMEPLATE VOLTAGE
Range: 100 to 50000 V in steps of 1 V
Default: 600 V
This setting represents the rated phase-to-phase motor voltage. The Motor Nameplate
Voltage setting is used as a reference for the voltage dependent thermal overload curve
feature and indicates a 100% voltage starting condition.
MOTOR HORSEPOWER
Range: 100 to 200000 HP in steps of 1 HP
Default: 4000 HP
This setting represents the motor rated horsepower (HP).
This setting is only needed in the Stator-Inter-Turn Fault element to calculate negative
sequence impedance when the setpoint Neg Seq Imp Autoset (see Monitoring > Stator-
Inter-Turn Fault) is programmed as Auto.
EMERGENCY RESTART
Range: FlexLogic operand
Default: Off
This feature must only be used in an emergency, as it defeats the purpose of the relay –
protecting the motor. The input selected by the setting is used to reset the motor
thermal capacity used from its current value to 0%, so that a hot motor may be
SYSTEM
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