Explore topic-wise MCQs in Electrical Engineering Questions.

While performing sumpner’s test on transformer, if the secondary are not in series opposition then the meter will read

A 10 kVA, 2000 / 100v transformer has R1=1.5 ohm, R2=0.005 ohm, X1=2.5 ohm and X2=0.08 ohm. The equivalent resistance referred to primary is

For maximum efficiency in a transformer

A 600 kVA transformer has iron losses of 400 kW and copper losses of 500 kW. Its kVA rating for maximum efficiency is given by

If the applied voltage of a certain transformer is increased by 50% keeping the frequency constant, the maximum flux density will become

For parallel operation of transformers, the most satisfactory condition is achieved when the load shared by the transformers is in exact proportion with their

If the supply voltage is kept at constant value and the supply frequency is increased. The magnetizing and core loss component

For a certain transformer if E1 is the emf across primary winding, E2 is the emf across secondary winding and K is the ratio of secondary to primary turns. The value of secondary emf referred to the primary side is

For a single phase no load transformer, which among the following losses will be minimum?

Which test is also called as back to back test?

The globules of water present in oil may result directly in a breakdown. This can be prevented by

In a transformer tank, grounding is given to protect it from lightening stoke. Grounding lug is usually installed near

In a step-up transformer when the voltage delivered is higher than that received, the current delivered is

What happens if dc supply is given to the transformer?

For a transformer, permeability and hysteresis loss should be

During starting, the magnetic field produced in a transformer is

For transformers ratings are always given in kVA, not in kW because

With increase in load, the speed of synchronous motor

The method used for starting synchronous motor is/are

In case of hydro generators, the driving torque can be changed by controlling the

A synchronous motor is started by using damper winding. When the motor runs at synchronous speed then the induced emf in the damper winding will be

Back emf in case of synchronous motor depends on the

If the load on a synchronous motor increases then its

According to Blondel’s two reaction theory the armature mmf is divided into components, direct axis component and quadrature axis component. The component acting along quadrature axis is

When an alternator is connected to infinite bus bar, change in excitation for alternator will

The increase in mechanical torque in case of alternator will

If a three phase winding is displaced in space by 120 degree in a synchronous motor then the magnitude of resultant flux when it is rotated by Θ = 0 degree and Θ = 60 degree is

Hunting in a synchronous motor results in

For a half cycle of fluxes in a synchronous motor, the resultant flux has rotated through

The reluctance offered to the mmf wave is lowest when

According to Blondel’s two reaction theory, the armature mmf component acting along direct axis can be

The synchronous reactance of an alternator is equal to

If the frequencies of the two alternators in lamp dark method for synchronization of alternators are unequal, then the two lamps will

In lamps dark method for synchronization of single phase alternator, if the frequency of two alternators is exactly same as well as their voltages are in exact phase opposition then the resultant voltage will be

For synchronization of single phase alternators which method gives the more accurate result?

Which method for finding percentage regulation in synchronous machines is called pessimistic method?

For high capacity alternators, which method is not suitable for finding percentage regulation?

Low value of SCR in an alternator indicates

For finding voltage regulation of an alternator, the method which gives most accurate result is

If the value of SCR in an alternator is low then the air gap and voltage drop across synchronous reactance will be

In Potier’s triangle method, to determine armature leakage reactance and armature reaction mmf separately, the tests performed are

For reducing the slot harmonics in an alternator, the length of air gap is

The open circuit voltage and short circuit current of a 3 phase, star connected alternator are 1050 V and 250 A respectively. Its field current is 12 A. Then the synchronous impedance of alternator will be

When the voltage across any two terminals of an armature winding of star connected alternator, then the armature resistance per phase is

If x is the order of harmonic component, then the general expression for distribution factor is

To minimize the harmonics from the voltage waveform, the suitable steps is / are

Generally the effective resistance of alternator under a.c. condition is taken as

The leakage flux in the armature of alternator makes the armature winding

Salient pole alternators are best suitable for the application of

The air gap in a salient pole machine is