Those machines in which the flux is practically constant. (b) Those machines in which flux is varying. (c) Those machines in which flux is proportional to armature current. (d) None of the above.
the stray losses. (b) the copper losses. (c) the eddy current losses. (d) the friction losses.
(a) true. false.
Reduce the weight per KVA. (b) Increases weight per KVA. (c) Has no relation with the weight of the transformer. (d) Increases the weight per KW.
(a) cooling only. (b) insulation only. insulation and cooling both . (d) lubrication only.
(a) Moisture will reduce the density of the oil which is slightly undesirable. Moisture will reduce the dielectric strength of the oil and hence insulation is weakened. (c) Moisture will reduce the lubricating property of the oil. (d) Moisture will develop rust.
(a) Natural mineral oil used in the transformer. Synthetic insulating fluids used in the transformer. (c) Insulating materials for transformers. (d) Insulating materials for motors and generators.
(a) To supply oil to transformer whenever needed. To protect transformer from damage when oil expands due to rise in temperature. It stores the increasing volume of the oil. (c) To provide the fresh air cool down the oil. (d) To store ware for transformer cooling.
(a) Induction coil works on A.C. (b) Transformer is used to step up the potential of d.c. The output current of induction coil is nearly unindirectional. (d) In the step down transformers, the transformation ratio is always greater than one.
(a) Frequently of the supply only. (b) Number of turns in secondary only. (c) Maximum flux in core and frequency only. Frequency, flux and number of turns in the secondary.
true. (b) false.
(a) R2/K2. (b) R2/2/K2. R2/K2. (d) R2/√K.
true. b) false.
(a) true. false.
(a) true. false.
(a) The iron loss at any load. The copper loss at any load or at full load. (b) The hysteresis loss. (c) The eddy current loss.
(a) true. false.
(a) true. false.
true. b) false.
(a) D.C. shunt motor. Transformer. (c) Induction motor. (d) Synchronous motor.