AP ECET EEE 2017-3

1. In RLC Circuits,the current at resonance is

A. Maximum in Series RLC Circuit, minimum in Parallel RLC Circuit
B. Manimum in Series RLC Circuit, maximum in Parallel RLC Circuit
C. Maximum in both Circuits
D. Minimum in both Circuits

Answer : Maximum in Series RLC Circuit, minimum in Parallel RLC Circuit
Explain:-

2. The power consumed by a coil is 300w when connected to a 30v DC source and 108w when connected to 30v Ac source.The Reactance of coil is

A. 3 Ω
B. 4 Ω
C. 5 Ω
D. 6.67 Ω

Answer : 4 Ω
Explain:-

3. If the source of 200v RMS supplies active power of 600w and reactive power of 800VAR the RMS current drawn from the supply

A. 10A
B. 5A
C. 3.75A
D. 2.5A

Answer : 5A
Explain:-

4. A 3phase delta connected symmetrical load consumes P Watt of power from a balanced supply.If the same Load is connected in star to the same supply, then what is power consumption

A. P/3
B. P
C. √3P
D. 3P

Answer : P/3
Explain:-

5. The desirable properties of transformer core material are

A. Low permeability and low hysteresis loss
B. High permeability and high hysteresis loss
C. High permeability and low hysteresis loss
D. Low permeability and high hysteresis loss

Answer : High permeability and low hysteresis loss
Explain:-

6. Two single phase 100KVA transformers,each having different leakage impedances are connected in parallel. When a load of 150KVA at 0.8 power factor lagging is applied then

A. Both transformers will operate at power factor more than 0.8 lagging
B. Both transformers will operate at power factor less than 0.8 lagging
C. One of the transformers will operate at power factor more than 0.8 lagging and other will operate at power factor less than 0.8 lagging
D. Both transformers will operate at identical power factors

Answer : One of the transformers will operate at power factor more than 0.8 lagging and other will operate at power factor less than 0.8 lagging
Explain:-

7. The most essential condition for parallel operation of two 1-phase transformers is that they should have the same

A. KVA Rating
B. percentage impedance
C. polarity
D. voltage ratio

Answer : polarity
Explain:-

8. It is advisable to use auto transformer if the transformation ratio is

A. Greater than 1
B. Near to 1
C. 0.25
D. 0.5

Answer : Near to 1
Explain:-

9. In a transformer, zero voltage regulation at full load is

A. Not possible
B. Possible at leading power factor load
C. Possible at lagging power factor load
D. Possible at unity power factor load

Answer : Possible at leading power factor load
Explain:-

10. If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then

A. Both hysteresis loss and Eddy current loss in the core will increase
B. Hysteresis loss will increase but Eddy current loss in the core will decrease
C. Hysteresis loss will decrease but Eddy current loss in the core will increase
D. Hysteresis loss will decrease but Eddy current loss in the core will remain unchanged

Answer : Hysteresis loss will decrease but Eddy current loss in the core will remain unchanged
Explain:-