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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Which relay is used for feeder?
MHO relay
Translay relay
Merz prize protection relay
Buchholz relay
Translay relay
Quick Summary: The Translay relay is a type of pilot wire differential relay specifically designed for the protection of short feeders and transmission lines. It works on the principle of circulating current or opposed voltage, ensuring fast and selective isolation of faulty sections in a power system.
The Translay relay is a type of pilot wire differential relay specifically designed for the protection of short feeders and transmission lines. It works on the principle of circulating current or opposed voltage, ensuring fast and selective isolation of faulty sections in a power system.
Idiff=I1−I2 — Represents the differential current in the protection zone
Vpilot=I×Zpilot — Represents voltage drop across pilot wires
The Translay relay utilizes two identical transformers, one at each end of the feeder, connected by pilot wires. Under normal operating conditions, the secondary currents produced in the two relays are equal and opposed, resulting in zero current flowing through the operating coils. During a fault, this balance is disturbed, causing current to flow through the relay operating coils, which subsequently trips the circuit breaker.
Translay relays provide unit protection for feeders.
They are insensitive to power swings and external faults.
The protection is based on the comparison of currents at the two ends of the protected line.
Pilot wire impedance does not significantly affect the relay performance.
High speed of operation
Excellent discrimination between internal and external faults
Simple construction
Requires pilot wires between relay locations
Limited by the maximum length of pilot wires due to charging current effects
Protection of short transmission lines
Feeder protection in industrial power systems
MHO relay is a distance relay used for long transmission lines.
Merz-Price protection is typically used for generator and transformer winding protection.
Buchholz relay is a gas-actuated relay used for transformer internal fault protection.
B is correct — The Translay relay is a specialized pilot wire differential protection scheme widely used for the protection of feeder circuits.
Always remember: Buchholz is for transformers, MHO is for long lines, and Translay is for short feeders.