GATE EE
Power System Analysis
Switch Gear and Protection
Previous Years Questions

## Marks 1

The most commonly used relay, for the protection of an alternator against loss of excitation, is
A negative sequence relay is commonly used to protect
A two machine power system in shown below. Transmission line $$XY$$ has positive sequence impedance of $${Z_1}\Omega$$ and zero sequence impedance of...
In a biased differential relay the bias is defined as a ratio of
The transmission line distance protection relay having the property of being inherently directional is
Consider the problem of relay co-ordination for the distance relays $$R1$$ and $$R2$$ on adjacent lines of a transmission system figure. The Zone $$1... In a 3-step distance protection, the reach of the three zones of the relay at the beginning of the first line typically extends upto In an inverse definite minimum time, electromagnetic type over-current relay, the minimum time feature is achieved because of Reactance relay is normally preferred for protection against If the fault current is$$2000$$A, the relay setting is$$50$$% and CT ratio is$$400:5,$$the plug setting multiplier will be A Buchholz relay is used for ## Marks 2 A$$3$$-phase transformer rated for$$33 kV/11kV$$is connected in delta/star as shown in figure. The current transformers$$\left( {C{T_s}} \right)$$... The over current relays for the line protection and loads connected at the buses are shown in the figure. The relays are IDMT is natural having the... Consider a stator winding of an alternator with an internal high resistance ground fault. The currents under the fault condition are as shown in the f... Match the items in List-$$I$$(Type of transmission line) with the items in List-$$II$$(Type of distance relay preferred) and select the correct ans... Voltage phasors at the two terminals of a transmission line of length$$70$$km have a magnitude of$$1.0$$per unit but are$$180$$degrees out of p... A list of relays and the power system components protected by the relays are given in List-$${\rm I}$$and List-$${\rm II}$$respectively. Choose the ... The plug setting of a negative sequence relay is$$0.2A.$$The current transformer ratio is$$5:1$$. The minimum value of line to line fault curr... The neutral of$$10MVA,11kV$$alternator is earthed through a resistance of$$5$$ohms. The earth fault relay is set to operate at$$0....
The distribution system shown in figure is to be protected by over current system of protection. For proper fault discrimination directional over curr...

## Marks 5

The per unit voltages of two synchronous machines connected through a lossless line are $$0.95\,\angle {10^ \circ }$$ and $$1.0\,\angle {0^ \circ }.$$...
The distance relay with inherent directional property is known as ________relay.
Type of Relay $$A.$$ Buchholz Relay $$B.$$ Translay relay $$C.$$ Carrier current, phase comparison relay $$D.$$ Directional over Current relay $$E.$$ ...
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