GE Multilin G650 Manual page 201

5.4 PROTECTION ELEMENTS
Table 5–58: RESTRICTED GROUND FAULT INTERNAL STATES
5.4.6.1 RESTRICTED GROUND FAULT SETTINGS EXAMPLE
5
SETPOINT > PROTECTION ELEMENTS > GROUND CURRENT > RESTRICTED GND FAULT >
RESTRICTED GND FAULT 1> RESTRICTED GND FAULT 2 > RESTRICTED GND FAULT 3
SETTING DESCRIPTION
Restricted Ground Fault Function permission
Restricted Ground Fault Pickup
Restricted Ground Fault Slope
Restricted Ground Fault Delay
Snapshot Event generation
SETPOINT > SYSTEM SETUP > GENERAL SETTINGS
SETTING DESCRIPTION
Phase CT Ratio
Ground CT ratio
The example does not apply any slope, it is only intended to explain the pickup setting selection when the CT ratios are
different for phases and ground.
• If the Phase CT Transformers are 400/5 this means a Phase CT Ratio of 80
• If the Ground CT Transformer is 200/5 this means a Ground CT Ratio of 40
Sensitivity is given in primary amperes with Phase CT Ratio reference, this is:
If the Ground Fault Pickup setting is 0.3 A. This setting means that for phases the unit will trip when the Igd with phase
current reference is higher that 24 A, and with ground current reference is higher than 12 A.
5-58
RESTRICTED GROUND FAULT INTERNAL STATES
RESTR GND FLT1 PKP
RESTR GND FLT1 OP
RESTR GND FLT2 PKP
RESTR GND FLT2 OP
RESTR GND FLT3 PKP
RESTR GND FLT3 OP
NAME
Function
Ground Fault Pickup
Ground Fault Slope
Ground Fault Delay
Snapshot Events
NAME
Phase CT Ratio
Ground CT Ratio
Sens =[Ground Fault Pickup] x [Phase CT Ratio]
G650 Generator Protection & Control System
DEFAULT VALUE STEP
DISABLED N/A
0.30 0.01 CT
0.00 0.01 %
0.10 0.01 s
ENABLED N/A
DEFAULT VALUE STEP
80.0 0.1
40.0 0.1
5 SETTINGS
RANGE
[DISABLED – ENABLED]
[0.02 : 20.00]
[0.00 : 100.00]
[0.00 : 600.00]
[DISABLED – ENABLED]
RANGE
[1.0 : 6000.0]
[1.0 : 6000.0]
GEK-113285A