AP ECET EEE 2020-3

1. A parallel AC Circuit in resonance will

A. Have a high voltgae developed across each inductive and capacitive section
B. Have high impedance
C. Act like a resistor of low value
D. Have current in each section equal to the line current

Answer : B. Have high impedance
Explanation:-

2. In an RL series circuit R=10ohm and Xl=17.32ohm. The phase angle in degrees between voltage and current is

A. 30
B. 45
C. 60
D. 90

Answer : C. 60
Explanation:-

3. A three phase, balanced delta connected load of 25∠-63°Ω is connected across a 400V,3-Phase balanced supply.Determine the phase current IR?(Assume phase sequence to be RYB

A. 15∠-63.4°A
B. 25∠63.4°A
C. 25∠-63.4°A
D. 16∠63.4°A

Answer : D. 16∠63.4°A
Explanation:-

4. By using two wattmeter method, power can be measured in

A. 3-phase,3-wire system
B. 3-phase,2-wire system
C. 3-phase,4-wire system
D. 1-phase,2-wire system

Answer : A. 3-phase,3-wire system
Explanation:-

5. The purpose of provideing iron core is to

A. Provide support to windings
B. Reduce hysteresis loss
C. Decrease reluctance of magnetic path
D. Reduceeddy current loss

Answer : C. Decrease reluctance of magnetic path
Explanation:-

6. A good voltage regulation of a transformer means

A. Difference between primary and secondary voltages is more
B. Output voltage fluctuation from no load to full load is least
C. Output voltage fluctuation with power factor is least
D. Difference between primary and secondary voltages is least

Answer : B. Output voltage fluctuation from no load to full load is least
Explanation:-

7. The useful flux of a 1-phase transformer at full load is 2webers. At half load,the flux will be

A. 0.5Webers
B. 1 weber
C. 4 webers
D. webers

Answer : D. webers
Explanation:-

8. Why transformers connected in parallel should have same voltage ratio?

A. To avoid no load circulationg current
B. To avoid full load circulating current
C. To avoid other losses
D. To avoid all types of currents

Answer : A. To avoid no load circulationg current
Explanation:-

9. Breather is provided in a transformer to

A. Absorb moisture of air during breathing
B. the filter of a transformer oil
C. provide cold air in the transformer
D. insulation between windings

Answer : A. Absorb moisture of air during breathing
Explanation:-

10. The efficiency of two identical transformers under load conditions can be determined by

A. Short circit test
B. open circuit test
C. No load test
D. Back to Back test

Answer : D. Back to Back test
Explanation:-