Protection Engineering Basics and Schemes Protection Engineering | Page 197
When system is normal i 1 and i 2 are opposite in direction to each other, The vector sum ∆I = i 1 + i 2 of both currents( enter and exist) will be zero / user defined
Abnormal condition i 1 and i 2 are opposite in direction to each other, The vector sum ∆I = i 1 + i 2( but remember i1 and i2 both are in opposite direction when system is normal, means id i 1 is positive then i 2 is negative) of both currents( enter and exist) will be greater than zero / user defined
No impact if fault occurred outside Differential loop, we called it external fault situation, as external fault is out of Differential protection zone.( Fig 4D)