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DC Electric Machines, Electromechanical Energy Conversion Principles, and Magnetic Circuit Analysis: Practice Problems, Methods, and Solutions

127 SOLVED PROBLEMS

Question: 16.18

In a 200 V, 20 A, DC motor, the magnetic flux suddenly increases to about 10%. Calculate the current that this machine will deliver to the electrical grid. Herein, assume that the magnetic circuit of the machine is linear and the armature circuit resistance is 0.1 Ω. Difficulty level ○ Easy ...

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Question: 16.17

In a shunt DC motor, it is assumed that the magnetic circuit is linear. If the applied voltage is halved in the no-load condition, what will be the ratio of the new speed of the motor to the old one? Difficulty level ○ Easy ○ Normal ● Hard Calculation amount ○ Small ● Normal ○ Large 1) 0.5 2) 2 ...

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Question: 16.16

A shunt DC motor that has been connected to a variable mechanical load is supplied by a 200 V power source. When the motor is under load A, its speed and current are 157 rad/s and 20 A. However, when the motor is under load B, its speed and current are 167.5 rad/s and 18 A. Calculate the torque of ...

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Question: 16.15

The magnetization characteristics of a shunt DC motor are shown in Fig. 15.3. The field winding resistance of the motor is 80 Ω and assume that the developed electromagnetic torque of the motor is proportional to its speed. When the motor is supplied with 240 V, its armature current and speed are ...

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The magnetization characteristics of the shunt DC ...
Question: 16.13

A 200 V, 12 A, 1940 rpm, shunt DC motor has the armature winding resistance of 0.5 Ω. If the applied voltage decreases to about 150 V, calculate the speed of motor if the load torque remains constant, the magnetic circuit is linear, and the field current is negligible. Difficulty level ○ Easy ...

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Question: 16.14

The no-load current of a 220 V shunt DC motor at the speed of 1000 rpm is 2 A. If the full-load current of the machine is 35 A and the armature winding resistance is 0.2 Ω, what is the full-load electromagnetic torque developed? Assume that the magnetic flux remains constant and ignore the current ...

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Question: 16.12

The magnetization characteristics of a DC shunt machine at the speed of 1150 rpm are illustrated in Fig. 15.2. The machine is operated as a motor and supplied by a 215 V power source. The no-load speed of motor is 1075 rpm. Determine the field winding resistance. Difficulty level ○ Easy ○ Normal ...

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The magnetization characteristics of the shunt DC ...
Question: 16.11

The no-load characteristics of a shunt DC machine at the speed of 1000 rpm are as follows: ...

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Based on the information given in the problem, we ...
Question: 16.10

A 250 V shunt DC machine has the armature winding resistance of 1 Ω and the field winding resistance of 100 Ω. If the machine is supplied by a 250 V power source and draws the line current of 25 A, calculate the ratio of speed of the machine in generating mode to the motoring one. Difficulty level ...

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Question: 16.9

In a 10 kW, 200 V, shunt DC motor, the armature winding resistance and the field winding resistance are 0.1 Ω and 200 Ω, respectively. The motor is rotating at the speed of 713 rpm with the rated voltage. If the machine is operated as a generator, determine the speed needed for the same field ...

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