Switchgear And Protection — Winter 2022

Explain zones of protection. Why adjacent zones are overlapped?

Explain DMT and IDMT over current relay.

What are the essential quantities of protective relaying? Explain them.

Explain the concept of current discrimination for the protection of radial feeder.

Draw a neat diagram of induction cup type relay and explain its operating principle.

Draw the block diagram of a numerical relay and explain it.

Explain TSM and PSM for IDMT relays. How relay operating time is calculated?

State advantages and applications of distance relay.

Explain MHO relay with its characteristics on R-Xdiagram

Explain 3 stepped distance protection.

Explain in brief, how the percentage differential relay overcomes the drawbacks of simple differential relay.

Explain harmonic restrain relay.

Explain the construction and working of Buchholz relay.

Explain possible busbar faults.

Explain with a neat diagram frame leakage protection of busbar.

Draw and explain Merz Price Protection of alternator stator winding. State its advantages.

Explain induction motor protection against single phasing.

Explain the negative sequence protection of alternator.

List and explain the various abnormal operation conditions against which a large induction motor has to be protected.

Discuss the difference between the measuring CT and protecting CT.

Define the following terms related to current transformer.

Rated primary current ii) Rated short time primary current iii) Burden iv) Ratio error

Explain recovery rate theory and energy balance theory of arc interruption in AC circuit breaker.

Explain advantages and disadvantages of air blast circuit breaker?

Write a technical note on: Dielectric properties of SF6 gas.

Write a technical note on: Minimum Oil Circuit breaker