Sensitive Earth Fault Element - GE P741 Technical Manual

Settings
MiCOM P741, P742, P743
1.2.1.2

Sensitive earth fault element

The sensitive earth fault element is included for high impedance earthed systems and has
bias current control to guarantee stability under external faults or when there are significant
errors in the measurement CTs. The element is usually disabled for effectively earthed
systems with low impedance or solid earthing.
Menu Text
DIFF BUSBAR PROT
Diff Earth Fault (Diff busbar protection menu second part)
Diff Earth Fault
To enable (activate) or disable (turn off) the differential earth fault protection function. When
activated, the following functions are accessible.
IBiasPh>Cur.
Setting that determines the Earth fault element blocking characteristic
CZ Parameters
Earth Slope k CZ
N
Slope angle setting for the check zone biased differential Earth element.
I CZ>2 Current
DN
Setting that determines the minimum differential operating current for the check zone
biased differential Earth element
Zone Parameters
Earth Slope k 2
N
Slope angle setting for all discriminating zone biased differential Earth elements
>2 Current
I
DN
Setting that determines the minimum differential operating current for all the discriminating
zone biased differential Earth elements
Common
I >1 Current
DN
Setting for the Neutral circuitry fault monitoring characteristic for the minimum pickup
Earth slope k 1
N
Slope angle setting for the Neutral circuitry fault monitoring characteristic.
I >1 Alarm Timer
DN
Setting for the Neutral circuitry fault monitoring minimum pickup timer
Default Setting
Disabled Enabled/Disabled
2000 A 50 A
10% 0%
1200 A 10 A
10% 0%
1000 A 10 A
100 A 10 A
10% 0%
5.0s 0.0s
P74x/EN ST/Na7
Setting Range
Min. Max.
30.000 A 10 A
90% 1%
30.000 A 10 A
90% 1%
30.000 A 10 A
500 A 10 A
50% 1%
600.0s 0.1s
(ST) 4-15
Step Size
ST