4. A dc series motor having a resistance of 0.950 drives a fan for which the torque varies as the square of the speed. At 220V, the set runs at 300 rpm and takes 20 amp. The speed is to be raised to 500 rpm by increasing the terminal voltage. Determine the necessary voltage and the corresponding current assuming the field to be unsaturated.

4. A dc series motor having a resistance of 0.950 drives a fan for which the torque varies as the square of the speed. At 220V, the set runs at 300 rpm and takes 20 amp. The speed is to be raised to 500 rpm by increasing the terminal voltage. Determine the necessary voltage and the corresponding current assuming the field to be unsaturated.

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter32: Three-phase Motors

Section: Chapter Questions

Problem 13RQ: A squirrel-cage induction motor is operating at 1175 RPM and producing a torque of 22 Ib-ft. What is...

See similar textbooks

Similar questions

hotors a) What power is developed by a motor that turns at 1200 rpm and has a torque of 3.0 N-m?
A 240 V d.c. series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 ohm. The value of resistance which must be added to obtain rated torque at 1000 rpm is ?
A 250 V series motor has an armature resistance of 0.2 ohm and a series-fieldresistance of 0.18 ohm. If the speed is 6oo RPM when the current is 32 amps.What will be the motor speed when the load is reduced so that the current is18 amps, under which condition the percent flux change is 50 % of the percentcurrent change.
1. The operation of Commutator in DC Motor is * O a) to convert dc to ac O b) to convert ac to dc O c) to convert fixed dc to variable dc O reverse the current direction in the rotating windings each half turn
459. The current drawn by a 460 V dc motor of armature resistance 0.5 ohm and back emf 420 V is -
A 230v DC series motor takes 30A when giving its rated output at 1400 rpm. It has a field resistance of 0,4 ohms, Calculate the value of the resistance (Ra) of the armature when Eb = 200V. Select the correct response: 0.2 ohms 0.6 ohms 0.8 ohms 0.4 ohms
In a d.c. series motor, the torque developed is 20 Nm at 10 A. If the load current is doubled, the new torque will be (a) 60 Nm (c) 80 Nm (b) 45 Nm (d) 100 Nm
A 250V series motor draws a current of 40A. The armature resistance is 0.15 ohm and the field resistance is 0.05 ohm. Determine the maximum efficiency of the motor.
A series motor runs at 800rpm when the voltage is 400v and the current is 25 ampere the armature resistance is 0.4ohm and the series field resistance is 0.2ohm determine the resistance to be connected in series to reduce the speed to 600rpm with same current
A 400 V DC series motor develops shaft torque of 200 Nm at 80 percent efficiency while running at 1200 rpm. The current drawn by the motor in amperes is?
6. The motion in DC motor can be increased by the following factors... (you may choose more than one) * a) Using a stronger magnet b) Increasing the potential difference c) Increasing the current d) Increasing the number of turns on the coil
A 240 V series motor takes 40 amperes when giving its rated output at 1500r.p.m. Its resistance is 0.3 ohm. Find what resistance must be added to obtain rated torque at starting. * O 5.7 O 6.7 5.5 6.3