Protection Engineering Basics and Schemes Protection Engineering | Page 97

V n is nominal voltage of HT or LT side = √3V phase to Phase

S n is apparent power 4.2.1 Symmetrical Components

There are three sequence components in any system

� Positive � Negative � Zero

Suppose we have three phase current, then sequence components are,

Remember,

I a = I a0 + I a1 + I a2 I b = I b0 + a 2 I b1 + aI b2 I c = I c0 + aI c1 + a 2 I c2

I a0 = I b0 = I c0 I a1 = a 2 I b1 I a2 = aI b2 pg. 97