What is negative phase sequence protection in generator?

Negative Sequence Relay: Negative sequence relay is used to protect the alternator or generator from the unbalance loading & negative sequence component. The negative sequence current flows through the generator winding due to phase to phase short circuit.

What is negative sequence impedance?

Negative Sequence Impedance: The impedance offered by the flow of negative sequence current in the circuit is called the negative sequence impedance. Here the negative sequence indicates all the electrical quantities are having equal magnitude and displaced 120deg each other in opposite direction.

Why do we use negative sequence relay?

Negative sequence current relays are primarily applied to protect generators and motors but also sometimes used in transmission systems to detect unbalanced conditions and faults. When a generator is connected to a balanced load the phase currents are equal in magnitude and are 120 degrees from each other.

What causes negative sequence voltage?

A current or voltage unbalance between phases in magnitude or phase angle gives rise to negative and zero-sequence components. The negative sequence component has a rotation opposite that of the power system. The resulting eddy currents are very large and cause severe heating of the rotor.

What is negative sequence relay?

Negative sequence relay: It protects generators from the unbalanced load by detecting negative sequence current. A negative sequence current may cause a dangerous situation for the machine. The negative sequence relay has earthing which protects from phase-to-earth fault but not from phase-to-phase fault.

What is a negative relay?

Definition: A relay which protects the electrical system from negative sequence component is called a negative sequence relay or unbalance phase relay. The negative sequence relay protects the generator and motor from the unbalanced load which mainly occurs because of the phase-to-phase faults.