Protection Engineering Basics and Schemes Protection Engineering | Page 230

Relay internal resistance = R relay = 0.05 ohm

R stab = V s

I s

− R relay

=

39. 549 0.1 − 0. 05

R stab = 394.54ohms

Power rating = 4 ∗( V s 2

39. 5492 = 4 ∗(

394.54)

R Stab

)

P stab = 15.85769Watt

Metrosil Calculation: it is external VARISTOR, Connected in Parallel to relay, used to limit high voltage produced during external faults occurrence.

pg. 230