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.Management Sciences
Category: Transformers
In a transformer the resistance between its primary and secondary is____________?
A. zero
B. 1 ohm
C. 1000 ohms
D. infinite
In an actual transformer the iron loss remains practically constant from no load to full load because:____________?
A. value of transformation ratio remains constant
B. permeability of transformer core remains constant
C. core flux remains practically constant
D. primary voltage remains constant
C. secondary voltage remains constant
No-load current of a transformer has_____________?
A. has high magnitude and low power factor
B. has high magnitude and high power factor
C. has small magnitude and high power factor
D. has small magnitude and low power factor
A transformer core is laminated to__________?
A. reduce hysteresis loss
B. reduce eddy current losses
C. reduce copper losses
D. reduce all above losses
A shell-type transformer has_________?
A. high eddy current losses
B. reduced magnetic leakage
C. negligibly hysteresis losses
D. none of the above
Delta/star transformer works satisfactorily when______________?
A. load is balanced only
B. load is unbalanced only
C. on balanced as well as unbalanced loads
D. none of the above
Power transformers are designed to have maximum efficiency at___________?
A. nearly full load
B. 70% full load
C. 50% full load
D. no load
In the transformer the function of a conservator is to_______________?
A. provide fresh air for cooling the transformer
B. supply cooling oil to transformer in time of need
C. protect the transformer from damage when oil expends due to heating
D. none of the above
The no load current in a transformer lags behind the applied voltage by an angle of about_____________?
A. 180°
B. 120″
C. 90°
D. 75°
The purpose of providing iron core in a step-up transformer is?
A. to provide coupling between primary and secondary
B. to increase the magnitude of mutual flux
C. to decrease the magnitude of mag-netizing current
D. to provide all above features
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