Differential protection is a unit-type protection for a specified zone or piece of equipment. It is based on the fact that it is only in the case of faults internal to the zone that the differential current (difference between input and output currents) will be high.
What is differential protection in power system network?
Differential protection is one of the most widely used methods for protecting power transformer against internal faults. The technique is based on the measurement and comparison of currents at both side of transformer: primary and secondary lines.
What is percentage differential protection?
Percentage restrained differential relays measure the individual branch currents and quantify the through current in the zone of protection. The percentage restraint characteristic requires that the differential current be greater than a percentage of the through (restraint) current.
Which relay is used in transformer?
Relays for Transformer Protection
|SL||Voltage Ratio and Capacity of Transformer||Common Relays|
|9||400/220KV 315MVA||Differential Relay Overflux Relay Buchholz Relay OLTC Buchholz Relay PRV Relay OT Trip Relay WT Trip Relay Over Load (Alarm) Relay|
What is PS class CT?
PS Class CT is also known as PX Class or simply Class X Current Transformer. It is special type of current transformer meant for protection purpose. … Deviation in characteristics of CTs may lead to spill current in the secondary and even lead to actuation of protection element even under through fault condition.