Chapter 6 · MCQ Read Mode

Electrical Machines

A transformer transfers energy between two circuits mainly through:

The EMF equation of a transformer is given by E =:

In an ideal transformer, the turns ratio a = N1/N2 equals:

The core of a power transformer is laminated primarily to reduce:

Maximum efficiency of a transformer occurs when:

The open-circuit (OC) test on a transformer is primarily used to determine:

The short-circuit (SC) test on a transformer is primarily used to determine:

Voltage regulation of a transformer is defined as the change in:

An autotransformer differs from a two-winding transformer because it:

A pulse transformer is specifically designed to:

The EMF induced in a DC generator armature is classified as:

The function of a commutator in a DC generator is to:

The EMF equation of a DC generator is E =:

Which type of DC generator has its field winding connected in parallel with the armature?

Armature reaction in a DC machine refers to:

Poor commutation in a DC generator typically results in:

Interpoles (commutating poles) are used in DC machines primarily to:

Losses in a DC generator include copper losses, iron losses, and:

Before connecting two DC generators in parallel, it is essential that they have:

The magnetization (no-load) characteristic of a DC generator plots:

The working principle of a DC motor is based on the:

The back EMF (Eb) in a DC motor:

Which DC motor type provides high starting torque but has speed that varies greatly with load (and can “run away” at no load)?

Which DC motor type provides an almost constant speed regardless of load?

A starter is used when starting a DC motor mainly to:

Speed of a DC motor is directly related to back EMF and flux by:

A Brushless DC (BLDC) motor achieves commutation using:

Swinburne’s test on a DC machine is used to determine:

Regenerative braking of a DC motor works by:

Reversing the direction of rotation of a DC motor is achieved by:

The rotor of a squirrel cage induction motor:

The synchronous speed of an induction motor is given by:

Slip of an induction motor is defined as:

The frequency of the rotor-induced EMF in an induction motor equals:

At standstill, the slip of an induction motor is:

The Direct-On-Line (DOL) starting method for induction motors is simple but results in:

Speed control of an induction motor by varying the supply frequency is achieved using a:

An induction machine can act as an induction generator when driven by a prime mover:

Which single-phase induction motor type uses two different capacitor values — one for starting, one for running?

A shaded-pole single-phase induction motor is characterized by:

A synchronous generator (alternator) produces AC output at a frequency related to speed by:

The rotor of a synchronous generator used in high-speed steam/gas turbine plants is typically:

In a synchronous generator's equivalent circuit, the generated EMF is in series with the:

The power developed by a synchronous generator is primarily a function of:

Before paralleling (synchronizing) an alternator with the grid, which condition is NOT required?

A synchroscope is used to:

A Permanent Magnet Synchronous Generator (PMSG) differs from a conventional synchronous generator mainly because it:

PMSGs are particularly popular in which application?

Voltage regulation of a synchronous generator is defined as the percentage change in terminal voltage when:

The armature/stator winding of a synchronous generator is typically:

A synchronous motor runs at:

A synchronous motor is NOT inherently self-starting because:

The torque developed by a synchronous motor is proportional to:

The maximum (pull-out) torque of a synchronous motor typically occurs at a torque angle δ of:

Damper (amortisseur) windings on a synchronous motor rotor are mainly used to:

An under-excited synchronous motor draws current from the supply that is:

An over-excited synchronous motor draws current from the supply that is:

Because of its variable-excitation behaviour, an over-excited synchronous motor running with no mechanical load is often used as a:

Speed control of a synchronous motor (while remaining synchronized) can only be achieved by varying the:

The counter EMF (CEMF) of a synchronous motor is best described as the: