232. The purpose of a breather in a transformer is to
A. provide cooling to the winding
B. take insulting oil from the conservator
C. provide insulation to the winding
D. extract moisture from the air
233. Cross-over windings are used for
A. high voltage winding of large rating transformers
B. high voltages winding of small rating transformers
C. low voltage winding of small rating transformers
D. none of these
234. concentric windings are used with transformers, the
A. low voltage winding placed next to core
B. low voltage winding on the outerside In core-type
C. high voltage winding placed next to core
D. high voltage winding on the outerside
235. The yoke sections of transformers using hot-rolled laminations is made 15 per cent greater than that of the core so as to
A. to increase the size of the transformers
B. to reduce the copper loss
C. to reduce the iron loss in yoke and magnetizing current
D. to provide better cooling
236. When two single phase transformers are running in parallel and if the impedance triangles of the transformers are not identical in shape and size then
A. power factor of one transformer and power factor of common load will be same
B. power factors at which the transformers operate will be different from one another and again these will be different from power factor of common load
C. power factors at which the transformers operate will be same but different from power factors of common load
D. power factors at which the transformers operate and power factor of common load-all will be same
237. What is the typical use of a auto-transformer?
A. Control transformer
B. Isolating transformer
C. Variable transformer
D. Toy transformer
238. In a transformer the magnitude of mutual flux
A. varies at low loads and constant at high loads
B. is low at low loads and high at high loads
C. is high at low loads and low at high loads
D. same at all loads
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