If the flux of a dc motor approaches zero, its speed will approach infinity.
2.A series motor is working drawing a load current of 1A from the line if now the load is reduced such that the current drawn is halved, the speed of the machine (neglecting the saturation and armature resistance) would be
The speed of a dc shunt motor Falls slightly from no load to full load.
5.A dc shunt generator has an armature resistance of 0.1 and runs at 1200 rpm when delivering 50 kW at 250 V. The speed of the machine, when run as a motor fed from 250 V supply and drawing 50 kW will be approximately.
The dc motor, which can provide zero speed regulation at full load without any controller is Differential compound .
12.A dc shunt motor having unsaturated magnetic circuit runs at 1,000rpm with rated voltage. If the applied voltage is half of the rated voltage, the motor will run at
13.What happens to the speed when the flux is reduced by 10% in a 200 V dc shunt motor having an armature resistance of 0.2 ohm carrying a current of 50 A and running at 960 rpm prior to weakening of field. The total torque may be assumed constant. Neglect losses
Torque developed by the armature of a dc motor is proportional to (Magnetic flux per pole) x (Armature current).
16.What is the increase in torque expressed as percentage of initial torque, if the current drawn by a dc series motor is increased from 10A to 12A (neglect saturation)?