Instantaneous phase overcurrent elementsV I R R RK sp CT L p= + +( )2.2 EARTH FAULT PROTECTION2.2.1 DIRECTIONAL ELEMENTSInstantaneous earth fault overcurrent elementsV I R R R RnKfnCT L p= + + +2 2( )2.2.2 NON-DIRECTIONAL ELEMENTSTime-delayed earth fault overcurrent elementsV I R R R RKcnCT L p n= + + +2 2( )Instantaneous earth fault overcurrent elementsV I R R R RK sn CT L p n= + + +( )22.3 SEF PROTECTION (RESIDUALLY CONNECTED)2.3.1 DIRECTIONAL ELEMENTSTime delayed SEF protectionV I R R R RnKcnCT L p≥ + + +2 2( )Instantaneous SEF protectionV I R R R RnKfnCT L p≥ + + +2 2( )2.3.2 NON-DIRECTIONAL ELEMENTSTime delayed SEF protectionV I R R R RnKcnCT L p≥ + + +2 2( )Instantaneous SEF protectionV I R R R RnKsnCT L p≥ + + +2 2( )P14D Chapter 9 - Current Transformer RequirementsP14D-TM-EN-8 179
