 # Electrical Engineering Objective Questions { DC Motors }

155. In a dc generator operating on load with its brushes on the geometrical neutral axis (GNA), the magnetic neutral axis (MNA) is shifted in the direction of rotation Now, if the brushes are given a lead of 90? (electrical), then the MNA will

156. A bipolar de machine with interpoles has a mainpole flux of 4) per pole and an inter-pole flux of 4); per pole. The yoke of the machine is divided into four quadrants by the main-pole axis and the commutation axis.The flux-distribution in the quadrants will be

157.  A cumulatively compounded dc motor runs at 1000 rpm at no-load. On full load, the flux increases by 10%, whereas the full load drop in the combined resistance of the armature and series field is 5%. Neglecting magnetic saturation, the full load speed will be nearly

158.  A 6-pole lap-connected de generator with 480 conductors has an armature resistance of 0.06 ohm. lithe conductors are reconnected to form a wave winding, other things remaining unchanged, the value of the armature resistance will be

159. A 2-pole series motor with its two field coils connected in series runs at a speed of 500 rpm. If the field coils ar reconnected in parallel and assuming that the torque is constant and the magnetic circuit is unsaturated, the new speed will be

160. On direct on line (DOL) starting, dc motor is found to rotate in the direction opposite to that for which it was designed. The motor is a

161. In a dc machine, the armature mmf is

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