GE Multilin 350 Series Instruction Manual page 187

CHAPTER 6: SETPOINTS
Ground/Sensitive
Ground instantaneous
overcurrent
protection
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
The relay has one Ground/Sensitive Ground Instantaneous Overcurrent protection element
per setpoint group. The settings of these functions are applied to the gound/sensitive
ground current for 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 0.00 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 97-99% of the pickup value.
The following path is available using the keypad. For instructions on how to use the
keypad, please refer to Chapter 3 - Working with the Keypad.
PATH: SETPOINTS > S3 PROTECTION > SETPOINT GROUP 1(2) > GROUND IOC1(2)
GND IOC FUNCTION
Range: Disabled, Trip, Alarm, Latched Alarm
Default: Disabled
The selection of the Latched Alarm, Alarm, or Trip setting enables the Ground/Sensitive
Ground IOC function. The output relay #1 "Trip" will operate, if the Ground/Sensitive
Ground IOC function is selected as Trip, and the measured ground current satisfies the
operating condition set by the settings. The "ALARM" LED will not turn on if the element
operates when set to function Trip. The "ALARM" LED will flash upon IOC operation, with
the IOC function selected as Alarm, and will self-reset, when this operation clears. If
Latched Alarm is selected as an IOC function, the "ALARM" LED will flash during the IOC
operating condition, and will stay "ON" after the condition clears, until a reset command
is initiated. The output relay #1 "Trip" will not operate if Latched Alarm or Alarm setting is
selected. Any or all of the output relays 3 to 6 can be selected to operate when the
Ground/S.Ground IOC function is selected as Latched Alarm, Alarm, or Trip.
GND IOC PKP
Range: Disabled, 0.05 to 20.00 x CT in steps of 0.01 x CT
Default: 1.00 x CT
SENS.GND IOC PKP
Range: 0.005 to 3.00 x CT in steps of 0.001 x CT
Default: 1.00 x CT
This setting sets the ground overcurrent pickup level specified per times CT. For example,
a PKP setting of 0.9 x CT with 300:5 CT translates into 270A primary current.
GND IOC DELAY
Range: 0.00 to 300.00 sec in steps of 0.01 sec
Default: 0.00 sec
This setting provides selection for pickup time delay used to delay the operation of the
protection.
OUTPUT RELAY 3 to 6
Range: Do not operate, Operate
Default: Do not operate
Any or all of the output relays 3 to 6 can be selected to operate upon Ground IOC
operation. The selection of relay outputs operation is available no matter whether
Latched Alarm, Alarm, or Trip function is selected.
BLOCK 1/2/3
Range: Off, Contact Input 1 to 10[8], Virtual Input 1 to 32, Remote Input 1 to 32, Logic
Element 1 to 16
Default: Off
Three blocking inputs are provided in the Ground IOC menu. When any of the selected
blocking inputs - Contact input, Virtual Input, Remote Input, or Logic Element - turns on,
the ground IOC function is blocked.
S3 PROTECTION
6–71