Test 001 Transformer

Electrical Engineering Practice Test

Electrical Machines

1. A transformer transforms

A) frequency
B) voltage
C) current
D) voltageand current

... Answer is D)

2. Which of the following is not a basic element of transformer

A) core
B) primary winding
C) secondary winding
D) mutualflux

... Answer is D)

3. In an ideal transformer

A) winding have no resistance
B) core has no losses
C) core has infinite permeability
D) all of the above

... Answer is D

4. The main purpose of using core in a transformer is to

A) decrease iron losses
B) prevent eddy current losses
C) eleminate magnetic hysteresis
D) decrese reluctance of the common magnetic circuit

... Answer is D)

5. Transfomer cores are laminatedin order to

A) simplify its constuction
B)minimise eddy current losses
C) reduce it
D) reduce hystersis loss

... Answer is d)

6. A stepup transformer increses

A) voltage
B)current
C)power
D) frequency

... Answer is A)

7. A transformer has negative voltage regulation when its load power factor is

A) zero
B)unity
C)leading
D)lagging

... Answer is C)

8. no load test on a tranformer is carried out to determine

A) copper loss
B) magnetic current
C) magnetising current nd bo load loss
D)efficiency f the transfomer

... Answer is C)

9. The simplest way to shift load from one dc shunt generator running in parallel with another is to

A) adjust their field rheostats
B)insert resistances in their armature circuits
C)adjust speeds of their prime movers
D)use equalizer connections

... Answer is A)

10. the main factor which leads to unstable parallel operation of flat and over compound dc generator is

A) unequal number of turns in their series field winding
B)unequal series field resistances
C)their rising voltage characteristics
D)unequal speed regulation of their prime movers

... Answer is C)