JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III SWITCH GEAR AND PROTECTION Previous Question Paper (August/September - 2024 - R16)

What are the different specifications to be considered in the design of a circuit breaker?

Write short notes on break down voltage of a circuit breaker.

Give the differences between differential relay and biased differential relay.

Give the application of over current relay, under voltage relay and direction relays.

List out various stator faults and rotor faults on a generator.

Give the advantages of Differential protection on bus bars.

List out the uses of counter poise wires.

Give the advantages of solid neutral grounding.

Define BIL. Give its significance.

What is insulation co-ordination?

Explain about the low resistance interruption theory with relevant characteristics.

A system having 220kV, the line to ground capacitance is 0.015 microfarad, inductance 4.5H. Find the voltage appearing across the pole of the circuit breaker if a magnetizing current of 8A instantaneous, is interrupted. Calculate also the value of resistance to be used across the contacts to eliminate the re-striking voltage?

Give the differences between minimum oil circuit breaker, air blast circuit breaker, vacuum and SF6 circuit breaker.

Derive the expression for re-striking voltage transient.

Explain the design and working of induction relay with a neat diagram and derive the torque equation.

Write short notes on percentage differential relay and give its applications.

Derive the universal torque equation and give the difference between different distance relays.

With a neat sketch, explain the working of Electromagnetic relays and give its applications.

Explain how a directional relay is used in the generator protection.

A 3 phase, 12MVA, 606kV generator is delivering a load of 10MW at 0.6 power factor, find the value of neutral resistance if 15% of the winding is unprotected. The relay setting is 20%. The per phase reactance is 10%.

A 11kV, 3 phase alternator has full load rated current of 250A. The reactance of the armature winding is 15%. The differential protection system is set to operate on earth fault currents of more than 250A. Find the neutral earthing resistance which gives earth fault protection to 90% of the stator winding?

A 3 phase transformer having a line voltage ratio of 400V/33kV is connected in star-delta. The CTs on the 400V side have a ratio of 800/5. Find the ratio of CTs on the 33kV side? Also draw the connection diagram?

Give the effects of ungrounded neutral on system performance of a system.

What is arcing grounds? Explain in detail.

Briefly discuss about the specifications of surge arresters.

Discuss the principle of operation of zinc oxide gapless arrester with neat diagram.

What is an impulse wave and give the specifications of standard impulse test wave?

What are the causes of over voltages arising in a power system? Why is it necessary to protect the lines and other equipment of the power systems against over voltages?