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# EMF & Torque Equation of DC Machines. Starter Quiz

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Question 1

Td vs Ia characteristic of a DC series motor is a-

Question 2

What is the increase in the torque expressed as percentage of initial torque. If the current drawn by a dc series motor is increased from 9A to 11A (Neglect saturation)?

Question 3Multiple Correct Options

A  pole, 220 V, 5 kW shunt motor gives 5 kW when running at 1000 rpm which draws armature and field currents of 25 A and 0.5 A and the armature resistance is 0.1 Ω and a drop of 1 volt per brush. The back emf (in V) and armature Torque of machine (in N-m) will be-

Question 4

A long shunt compound wound motor is having shunt field resistance, series field resistance and armature resistance of 300 Ω, 0.8 Ω and 0.6 Ω respectively. If the motor is drawing 60A at 500V, What is the voltage drop across series field resistance?

Question 5

If the applied voltage to a DC motor is 240 V, then back emf for maximum power developed is-

Question 6

A 240V series takes 50A when giving its rated output at 1000rpm. Its resistance is 0.8Ω. Then, find the resistance that must be added in series of armature to obtain rated torque at starting _________Ω.

Question 7

220 V, dc series motor takes 50 A when delivering its rated output at 1500 rpm. If the total armature resistance is 1 Ω. Then external resistance required to obtained rated torque at a speed of 900 rpm will be_____Ω.
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