GE P24DM, Technical Manual

Page: 219 / 600

2.1.2 NON-DIRECTIONAL ELEMENTS
Time-delayed phase overcurrent elements
V
I
R R R
K
cp
CT L p
= + +
2
( )
Instantaneous phase overcurrent elements
V I R R R
K sp CT L p
= + + ( )
2.2 EARTH FAULT PROTECTION
2.2.1 DIRECTIONAL ELEMENTS
Instantaneous earth fault overcurrent elements
V
I
R R R Rn
K
fn
CT L p
= + + +
2
2 ( )
2.2.2 NON-DIRECTIONAL ELEMENTS
Time-delayed earth fault overcurrent elements
V
I
R R R R
K
cn
CT L p n
= + + +
2
2 ( )
Instantaneous earth fault overcurrent elements
V I R R R R
K sn CT L p n
= + + + ( ) 2
2.3 SEF PROTECTION (RESIDUALLY CONNECTED)
2.3.1 DIRECTIONAL ELEMENTS
Time delayed SEF protection
V
I
R R R Rn
K
cn
CT L p
≥ + + +
2
2 ( )
Instantaneous SEF protection
V
I
R R R Rn
K
fn
CT L p
≥ + + +
2
2 ( )
P24xM Chapter 9 - Current Transformer Requirements
P24xM-TM-EN-2.1 195