# Test: Rotating Amplifiers

## 15 Questions MCQ Test Electrical Machines | Test: Rotating Amplifiers

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Attempt Test: Rotating Amplifiers | 15 questions in 10 minutes | Mock test for Electrical Engineering (EE) preparation | Free important questions MCQ to study Electrical Machines for Electrical Engineering (EE) Exam | Download free PDF with solutions
QUESTION: 1

### The rotating amplifiers are widely used in

Solution:

The rotating amplifiers are applicable in feedback systems giving large amplified outputs.

QUESTION: 2

### The quantity which make rotating amplifier applicable in large power levels is/are

Solution:

The rotating amplifiers have stable transient conditions, which makes them favourable to use in high power sectors.

QUESTION: 3

### The ordinary dc machines are not favourable as amplidynes due to

Solution:

The sluggish transient response of the ordinary dc machines makes them inappropriate to use them in amplidynes.

QUESTION: 4

In rotating amplifiers, armature reaction mmf of the first stage is made to act as field flux for second stage.

Solution:

Yes, the reaction mmf of the first stage is made to act as field flux for second stage to have faster transient response.

QUESTION: 5

The cross field machines have

Solution:

The cross field machines have two fluxes electrically in quadrature.

QUESTION: 6

In cross field rotating amplifiers, there is

Solution:

There are two stages for flux generators in order to have faster response in the system.

QUESTION: 7

Metadyne is _________ feedback with respect to main ___________

Solution:

Metadyne is negative feedback with respect to main current flowing in the second stage set of motors.

QUESTION: 8

An amplidyne, d-axis flux is always neutralized due to

Solution:

The d-flux is neutralized by compensating winding at all possible loads as the same flux will be produced but in the opposite direction so as to cancel the flux.

QUESTION: 9

In amplidynes, the resultant d-axis flux is

Solution:

The resultant d-axis flux lies along the main field poles and are so field flux. The d- axis is completely under the control of field winding and is unaffected by direct axis current.

QUESTION: 10

Amplidynes are best applicable in

Solution:

Amplidynes find applications in feedback systems with large power handling requirements.

QUESTION: 11

Interpoles provide mmf more than armature mmf in a dc machine.

Solution:

Interpoles nullify armature cross magnetizing flux and the reactance voltage. So it is more than the armature mmf for a good efficient machine.

QUESTION: 12

The delay of the commutation occurs due base cause of emf induced due to

Solution:

The commutation in dc machines is delayed because of the emf induced in the coils and the mutual interaction of the field with neighbour coils.

QUESTION: 13

I. DC shunt motor – variable speed application
II. DC compound generator – constant supply voltage
III. Differentially compounded motor – welding purposes
Above are the applications of the dc machines , but all are not matched correctly. Choose the wrong marking

Solution:

Differentially compounded generators are used for welding purposes, not motors.

QUESTION: 14

I. DC shunt motor – Lathe machine
II. DC compound generator – Drilling machine
III. Differentially compounded generator – welding purposes
Above are the applications of the dc machines, but all are not matched correctly. Choose the wrong marking

Solution:

DC compound generators are used for maintaining constant voltage across the terminals.

QUESTION: 15

Mark the order for the decreasing order of the voltage regulation for dc generators

Solution:

Dc shunt motor is almost constant speed generator and thus its voltage regulation is very good than all and differential compound generator has most poor v.r.

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