GE Industrial Solutions Entellisys System User Manual - Manual (Page 77)

Single Point Relay protection 77
5
5.2.8 High Resistance Ground Fault Relay
The Entellisys system provides an optional High Resistance Ground Fault Detection (HRGF)
Function that is an alarm-only function that does not trip the circuit breaker.
The relay can be in three states:
• Pickup – If the ground current in any phase is more than the pickup set point, the relay goes
into pickup, and is said to enter Pickup state.
• Operate – If the relay stays in pickup state for a specified pick up delay time, the system
activates an alarm, and the relay is said to be in Operate state.
• Drop out – The relay drops out of pickup when the ground current drops below 97% of the
programmed threshold. The relay is said to be in Drop out state.
The HRGF pickup is programmable from 2.0 amps to 10.0 amps of ground current in steps of 0.1
amps. The delay setting is programmable from 0.5 to 5 seconds in steps of 0.1 second. A
constant time curve is used for HRGF. If the ground current is above the pickup threshold, the
system logs an event. If the ground current remains above the threshold for longer than the
delay setting, the system logs an event and activates an alarm.
5.2.8.1 Accuracy
Pickup accuracy is ± 10%.
5.2.8.2 Setup
The HRGF relay is a per line-up option.
To set the Alarm settings for the HRGF relay
1. On the Main Menu, click User Settings, and then select Relay Protection.
2. On the Relay Protection screen, choose the circuit breaker number from the drop-down
menu and click High Resistance GF.
The remainder of this section discusses the relay parameters that can be set in the High
Resistance GF section of the Relay Protection screen as shown in Figure 5-11.
5.2.8.3 Alarm settings
Relay Enabled: Select Enabled to enable the relay.
Pickup: Adjust the HRGF pickup from 2 Amps to 10 Amps in increments of 0.1 Amp from the
Pickup Setting drop-down menu.
Delay: Adjust the HRGF delay from 0.5 to 5 seconds in steps of 0.1 second from the Time Delay
drop-down menu.
Ground Resistance: Adjust the Ground Resistance from 5 to 500 ohms in steps of 1 ohm from
the Ground Resistance drop-down menu.