Restricted Ground Fault (Only For Enhanced Models) - GE Multilin G650 Manual

5.4 PROTECTION ELEMENTS
G650 provides the possibility of having a RGF (Restricted Ground Fault) function, only available for Enhanced models
(please see ordering code). This RGF function is based in the comparison of the neutral current calculated from phase
currents with ground current measured from the fourth current input (B9-B10). The implementation is a low impedance
current differential scheme. G650 calculates the vectorial difference of the residual and ground currents (3I
this by the maximum line current (I
5
The RGF settings are shown on the table below:
Table 5–54: .RESTRICTED GROUND FAULT SETTINGS
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
• Restricted Ground Fault Function: This setting allows enabling or disabling the restricted ground fault element.
• Restricted Ground Fault Pickup: This setting defines the minimum differential current required for operation in units
of Phase CT Ratio.
• Restricted Ground Fault Slope: This setting defines the restraint during normal operation conditions to assure
sensitivity to internal faults. Slope percentage of ground differential current to maximum line current.
• Restricted Ground Fault Delay: Time that the element must remain picked up before the element operates.
5-56

5.4.6 RESTRICTED GROUND FAULT (ONLY FOR ENHANCED MODELS)

) to produce a percent slope value.
max
Figure 5–9: RESTRICTED GROUND FAULT IMPLEMENTATION
Name
Function
Ground Fault Pickup
Ground Fault Slope
Ground Fault Delay
Snapshot Events
G650 Generator Protection & Control System
Default Step
Disabled N/A
10.00 0.01 CT
10.00 0.01%
0.10 s 0.01
Enabled N/A
5 SETTINGS
-I ) and divides
0 g
Range
Disabled - Enabled
0.02 - 20.00 CT
0.00 - 100.00%
0.00 - 600.00 s
Disabled - Enabled
GEK-113285A