Explore topic-wise MCQs in Electrical Engineering Questions.

In double delta transformation, a double delta refers to the case where there are two delta transformations in

The value of load angle δ and the internal machine angle ∅ for maximum power developed in synchronous motor is equal to

What happens if a stationary alternator is connected to live bus bar?

If a d.c. series motor is started on very light load or on no load then

If the flux is increased by 50% and speed is reduced by 50% of a d.c. motor (keeping the other parameters constant), then its back emf will become

In a single phase, full wave bridge circuit and in three phase, delta full wave bridge circuit, the ripple voltage frequency is always

During the one complete revolution of the conductor in a 4 pole synchronous generator, induced emf will experience

Which method is suitable for the speed control, below and above the normal rated speed of d.c. shunt motor?

When the induction motor runs faster than the synchronous speed, the induction motor runs as

The performance of induction motor is effected by the harmonics in the

Ampere turns per pole for compensating winding in d.c. machines is equal to

In regenerative test, the supply is given to the motor

Swinburne’s test can be performed at

Due to presence of third harmonic component in the star-star connection of three phase transformer, the frequency of the circuit component becomes

In refrigerators the commonly used motors are

Brushes in d.c. machines are made up of

The most commonly used connections for power systems as a step - up and step - down transformers are

The brush contact losses in a d.c. Machine is

To perform field test on d.c. machines two motors are required. The motors used are

The back to back test is best suited for

The test which can be performed on the d.c. series motor is

Stray losses are the losses which vary with the load but their relationship with load current cannot be identified. Stay losses is maximum in

Copper losses in a rotating machine are

Iron losses are considered to be the constant losses. It depends on

For low reluctance path for the flux in armature, the permeability of the material should be

Electrical power output in a d.c. generator is equal to

The conductors which will cause distortion in the main field flux of d.c. machine are

Out of electrical, mechanical and magnetic losses, the losses which is minimum is

Mechanical power developed in armature of a d.c. motor is given by

A 6 pole wave wound d.c. generator has 460 armature conductors carrying armature current of 180 A. The armature reaction demagnetizing and cross magnetizing ampere turns per pole if brushes are shifted by 6 degree electrical from G.N.A are

The armature in d.c. machines are always placed on rotor

In a d.c. machine, the eddy current losses mainly occurs in

Two 4 pole d.c. machines of identical armature, one with wave winding and other with lap winding are wound. Then

Due to the effect of armature reaction in d.c. machine, the value of generated voltage and flux per pole

The armature reaction in d.c. machine causes distortion in the main field flux. This effect of armature reaction can be reduced by

For the parallel operation of three phase transformers, which among the following connection is not applicable?

While connecting three phase transformer in star-star connection, the terminals of secondaries are wrongly joined. Then the mutual phase angle and magnitude of line to line voltages of secondaries will

In a d.c. machine, the commutator provides

The phase shift in a star-star connected three phase transformer is

To have perfect neutralization of armature mmf under the pole shoe, the ampere conductors of compensating winding must be

In the biomedical instruments like artificial heart pumps, the commonly used motor is

If K is the transformation ratio, then the secondary phase voltage of delta-delta connected three phase transformer will be

For the construction of the armature of a d.c. machine, the best suited material is

For large low voltage transformers, the most commonly used connections are

In case of delta-star connection of three phase transformer, secondary line voltage with respect of primary line voltage is at

To have d.c. voltage, a device is used in a d.c. generator to convert alternating emf to unidirectional emf. This device is called

Yoke in d.c. machine serves the outermost cover. For magnetic flux it provides

Functions of commutator in d.c. machines are

In a d.c. machine, the form of armature reaction mmf is

If A is the number of parallel paths and P is the number of poles, then the number of parallel path in lap winding and in wave winding is