Q. III A 10-hp 230-volt shunt-wound motor has rated speed of 1000 rpm and full-load efficiency of 88%. Armature-circuit

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Q Iii A 10 Hp 230 Volt Shunt Wound Motor Has Rated Speed Of 1000 Rpm And Full Load Efficiency Of 88 Armature Circuit 1 (30.13 KiB) Viewed 48 times

Q. III A 10-hp 230-volt shunt-wound motor has rated speed of 1000 rpm and full-load efficiency of 88%. Armature-circuit resistance, 0.2682; field-circuit resistance, 225 22. If this motor is operating at rated load and the field current is very qu reduced to 50% of its rated value while the speed remains constant: a) What will be the effect upon the back emf (E.), armature current (I.) and torque (Ta)? b) Referring to Part (a) above, what value of resistance must be inserted in series with the armature of this motor in that the speed may be reduced to 50% of its rated value, and the torque is limited to 150% of the rated value? c) Referring to Part (b) What will be the new output power and efficiency of the motor?