Ground Instantaneous Overcurrent Protection (50G) - GE 889 Instruction Manual

PROTECTION
Ground Instantaneous
Overcurrent
Protection (50G)
NOTE:
NOTE
4–186
The 889 relay is equipped with the Ground Instantaneous Overcurrent protection element.
The settings of this function are applied to the measured Ground current for producing
Pickup and Trip flags. The Ground IOC Pickup flag is asserted when the Ground current is
above the PKP value. The Ground IOC Operate flag is asserted if the element stays picked-
up for the time defined by the Ground IOC PKP Delay setting. If the Pickup time delay is set
to 0.000 seconds, the Pickup and Operate flags will be asserted at the same time. The
element drops from Pickup without operation if the Ground current drops below 97 to 98%
of the Pickup value.
Path:
Setpoints > Protection > Group 1(6) > Current > Ground IOC 1(X)
FUNCTION
Range: Disabled, Trip, Alarm, Latched Alarm, Configurable
Default: Disabled
PICKUP
Range: 0.050 to 30.000 x CT in steps of 0.001 x CT
Default: 1.00 x CT
When Signal Input is selected as K1 ground input from 50:0.0.25 CT (B1/B5 order code), the
pickup setting must be done considering 1:1 CT ratio. The relay applies a ratio of 2000
internally to directly measure primary side ground current and apply into this function. For
example, a pickup setting 1.000 x CT translates to the pickup of the element when CT
primary current exceeds 1.000 Ampere (i.e. 0.5 mA injected into the relay from CT
secondary.)
DIRECTION
Range: Disabled, Forward, Reverse
Default: Disabled
PICKUP DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.000 s
DROPOUT DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.000 s
BLOCK
Range: Off, Any FlexLogic operand
Default: Off
OUTPUT RELAY X
For details see Common
EVENTS
Range: Enabled, Disabled
Default: Enabled
TARGETS
Range: Self-reset, Latched, Disabled
Default: Self-reset
Setpoints.
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS