5-56 G650 Generator Protection & Control System GEK-113285A
5.4 PROTECTION ELEMENTS 5 SETTINGS
5.4.6 RESTRICTED GROUND FAULT (ONLY FOR ENHANCED MODELS)
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
0
-I
g
) and divides
this by the maximum line current (I
max
) to produce a percent slope value.
Figure 5–9: RESTRICTED GROUND FAULT IMPLEMENTATION
The RGF settings are shown on the table below:
Table 5–54: .RESTRICTED GROUND FAULT SETTINGS
• 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.
SETPOINT > PROTECTION ELEMENTS > GROUND CURRENT > RESTRICTED GND FAULT >
RESTRICTED GND FAULT 1> RESTRICTED GND FAULT 2 > RESTRICTED GND FAULT 3
Setting Description Name Default Step Range
Restricted Ground Fault Function
Permission
Function Disabled N/A Disabled - Enabled
Restricted Ground Fault Pickup Ground Fault Pickup 10.00 0.01 CT 0.02 - 20.00 CT
Restricted Ground Fault Slope Ground Fault Slope 10.00 0.01% 0.00 - 100.00%
Restricted Ground Fault Delay Ground Fault Delay 0.10 s 0.01 0.00 - 600.00 s
Snapshot Event Generation Snapshot Events Enabled N/A Disabled - Enabled
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