Solved questions preview paper (2) 101-150

Q.101. The phase different between current 

and voltage is 90° , the real power will be
a.)Minimum
b.)Maximum
c.)Zero✔
d.)Cannot be determined

Q.102. Capacitor bank are connected with ac induction motor
a.)In parallel✔
b.)In series
c.)Not connected at all
d.)Can be connected either way series/parallel

Q.103.At resosnance
a.) Magnitude of capacitive reactance > magnitude of inductive reactance
b.)Magnitude of capacitive reactance =magnitude of inductive reactance✔
c.)Magnitude of capacitive reactance <magnitude of inductive reactance
d.)None of the above

Q.104. An RLC circuit has a resonance frequency of 160kHz and a Q-factor of 100, its bandwidth is
a.)1.6kHz✔
b.)0.625kHz
c.)16MHz
d.)None of these

Q.105. A 230 V, 100 W bulb is connected in series with a room heater . If now this bulb is replaced by a 230V , 40W bulb, the heater output will
a.)Decrease✔
b.)Increase
c.)Remain the same
d.)Unjustified

Q.106. A certain AC circuit has resistance of 100 ohm and impedance of 200 ohm the phase angle of voltage and current of the circuit is
a.)60°✔
b.)30°
c.)90°
d.)45°

Q.107. The time constant of an inductive circuit is one second if its inductance page 8 H, the resistance of the coil will be
a.)8ohm✔
b.)1/8ohm
c.)0.25ohm
d.)1ohm

Q.108.______can not sustain much voltage fluctuation
a.)Sodium vapour lamp
b.)Mercury vapour lamp
c.)Incandescent lamp✔
d.)Fluorescent lamp

Q.109. Clamping circuit are one which insert
a.) AC component in signal
b.) DC component in signal✔
c.) Both AC and DC
d.) None of these

Q.110. To a highly inductive circuit a small capacitance is added in series the phase angle between voltage and current will
a.)Decrease✔
b.)Increase
c.)Remain same
d.)Indeterminate

Q.111. Whenever current is supplied by a source its terminal voltage
a.)Increase
b.)Decrease
c.)Remain constant
d.) Increase exponentially

Q.112. Which of the following cannot be connected in series unless they are identical
a.)Voltage source
b.)Current source✔
c.)Both of above
d.)Resistance

Q.113. Series circuit consist of R 20 ohms, and L 20mH  and AC supply 60 volt with frequency 100 Hz the current in R is
a.)2.54 A✔
b.)1.27A
c.)5.08A
d.)10.16A

Q.114.If the resistor an inductor are connected in series across a voltage source. Which in two parameters in that circuit increases if frequency of voltage source increases?
a.)VL and Z ✔
b.)Z and I
c.)VL and I
d.)VL and VR

Q.115.The maximum number of  wattmeter (s) required to measure 3phase 3wire balanced or unbalanced power in delta connected load
a.) 0
b.) 2✔
c.) 3
d.) 6

Q.116. When ac supply given to the transformer , the flux will depend upon
a.)Current
b.)Voltage
c.)Frequency
d.)Both voltage and frequency✔

Q.117. The stationary alternator must not be connected to live bus bar because it will result in
a.)Short circut✔
b.)Open circuit
c.)Nothing will happen
d.)Floating

Q.118. Which one of the following statement is correct, for connecting a alternator to infinite bus?
a.)Phase sequence should be same✔
b.)Frequency need not be same
c.)Terminal.voltage of alternator need not be same with existing bus
d.) None of the above

Q.119. An alternator having induced
emf of 1.6 Pu connected to an infinite bus of 1.0 Pu, if the bus has reactance of 0.6 Pu and alternator has reactance of 0.2Pu . The maximum power that can be transferred is given  by.
a.)1Pu
b.)2Pu✔
c.)3Pu
d.)5Pu

Q.120.A 50Hz 4pole turbo generator rated at 20MVA 13.2kV has inertia constant H=3kW-sec/kVA. The kinetic energy stores in rotor
a.)80MJ
b.)60MJ✔
c.)20MJ
d.)10MJ

Q.121. In a series resonant circuit impedance is
a.) Minimum✔
b.) Maximum
c.) Zero
d.) None of these

Q.122. Class B amplifier is baised
a.) At mid point of load line
b.) Just at cutoff✔
v.) Nearly twice cut off
c.) None of the above

Q.123. For making a capacitor it is better to selected A dielectric having
a.) Low permittivity
b.) High permittivity✔
c.) Permittivity same as that of air
d.) Permittivity more than that of air

Q.124. Plug setting of a relay can be altered by varying
a.) Air gap of magnetic path
b.) No. of ampere turn✔
c.) Adjusttable back up stop
d.) None of these

Q.125. Class B insulator can be a temperature up to
a.)130✔
b.)120
c.)105
d.)90

Q.126. If the fault current is 2000 ampere the real setting is 50% and CT ratio is 400 : 5 then plug setting multiplier will be
a.)10A✔
b.)15A
b.)25A
c.)50A

Q.127. Sulphation in a lead acid battery occur due to
a.) Heavy charging
b.) Fast charging
c.) Trickle charging
d.) Incomplete charging✔

Q.128. An ideal voltage source should have
a.) Large value of EMF
b.) Small value of EMF
c.) Zero source resistance✔
d.) Infinite source resistance

Q.129. A coil of negligible resistance as an induction of 100 mH. tThe current passing through the coil changes from 2 ampere to 4 ampere at a uniform rate in 0.1 second the voltage across the coil during this time would be____V
a.)2✔
b.)8
c.)36
d.)50

Q.130. What is represented by the hypotenus of Impedance Triangle
a.) Apparent power
b.) Resistance drop
c.) Reactive drop
d.) Impedance drop✔

Q.131.A 60 watt bulb in series with a room heater is connected across the mains. If the 60 watt bulb is replaced by 100W bulb
a.)The heater output will increase✔
b.)The heater output will decreas
c.)The heater output will be same
d.)The heater output will slightly decrease

Q.132. A cube of material of side 1cm has a resistance of 0.02Ω between its opposite faces. If the same volume of the material has a length of 4cm and a uniform cross section , the resistance of this length will be
a.)0.128Ω
b.)0.064Ω
c.)0.032Ω✔
d.)0.016Ω

Q.133. Which one of the following is not a condition of parallel operation of transformer
a.)MVA rating of transformer must be same ✔
b.)Voltage ration of transformer must be same
c.)Percentage impedance  of transformer should be same
d.)Polarity of transformer must be identical

Q.134. If the supply frequency of a transformer increases the output voltage of the transformer will
a.) Decrease
b.) Increase proportionally✔
c.) Remain same
d.) Increase very rapidly

Q.135.In a core type transformer
a.) HV winding is placed nearer to the core limb
b.) LV winding is placed nearer to the core limb✔
c.) Any of the LV or HV can be placed nearer to the core limb
d.) HV and LV windings are placed in different Cor limb

Q.136. The primary secondary winding of a transformer are
a.) Conductivity linked
b.) Inductively linked✔
c.) Electrically linked
d.) MechanicallyLinked

Q.137. At what Power factor in the voltage regulation of a transformer can be zero
a.) Leading power factor✔
b.) Lagging power factor
c.) Unity power factor
d.) Zero power factor

Q.138. In a three phase Star delta transformer what is the angle between primary and secondary phase voltage
a.) Delta side legs by 30°
b.) Star side legs by 30°
c.) Star side leads by 30°
d.) Delta side leads by 30°✔

Q.139. What will be the Eddy current loss if the supply frequency of a transformer become double
a.) 8 times
b.) Remain same
c.) Doubled
d.) 4 time✔

Q.140. The efficiency of a transformer is mainly depend upon
a.) Core losses✔
b.) Copper losses
c.) Stray losses
d.) Dielectric losses

Q.141. If supply frequency of a transformer decreases
a.) Both Eddy current and hysteresis losses will increase
b.) Eddy current loss will increase but hystresis loss will decrease
c.) Both Eddy current hysteresis losses will decrease✔
d.) Eddy current loss will decrease but hysteresis loss will increase

Q.142. Transformers operating in parallel will share the load depending upon their
a.) Leakage reactance
b.) Rating✔
c.) Efficiency
d.) Percentage impedance

Q.143. No load primary current in a transformer
a.) Leg behind applied voltage somewhat less than 90°✔
b.) Lags behind applied voltage by exactly 90°
c.) Lead the applied voltage by exactly 90°
d.) Leads the applied voltage somewhat less than 90°

Q.144. Which of the following is minimised by laminating the core of a transformer
a.) Hysteresis loss
b.) Eddy current loss✔
c.) Copper loss
d.) Stray loss

Q.145. Breather is provided in a Transformer to
a.) Absorb moisture from air entering in Transformer as well as provide breathing to the Transformer✔
b.) Provide cold air in transformer
c.) Absorb moisture from air entering in Transformers
d.) Filter the Transformer oil

Q.146. Iron loss in transformer mainly occur in
a.) Iron made tank of transformer
b.) Steel core in transformer✔
c.) Winding of transformer
d.) Transformer insulating oil

Q.147. Which of the following losses in the Transformer varies with load
a.) Copper loss✔
b.) Eddy current loss
c.) Hysteresis loss
d.)Stray loss

Q.148. In a transformer the magnetic coupling between the primary and secondary winding can be increased by
a.) Increasing the number of turns
b.) Using soft material for winding
c.) Using the magnetic core of low reluctance✔
d.) Using Transformer oil of better quality

Q.149. The short circuit test on transformer is conducted to obtain
a.) Copper losses✔
b.) Core losses only
c.) Eddy current loss
d.) Hysteresis loss

Q.150. In a transformer short circuit test and open circuit test are conducted
a.)In LV side of transformer
b.)In HV side and LV side of transformer respectively ✔
c.)In LV side and HV side of transformer respectively
d.)In HV side of transformer