Problem 103-13    Source:  Problem prepared by the website author.

Based on the result of item a) of the previous problem and considering only the motor losses in armature resistance, determine:

a) the torque developed by the engine.

b) the motor efficiency considering the shunt configuration.

Solução do Problema 103-13   

Item a

To calculate the torque value we will use the eq. 103-16, repeated below.

To apply this equation we must first calculate the value of ω using eq. 103-12. Then:

From eq. 103-16 and after an algebraic arrangement, we get:

Item b

In order to find the value of the efficiency of the motor, we must first calculate the value of the power that the motor absorbs from the power supply. In the shunt configuration, we know that the line current is given by:

So the power that the motor absorbs from the supply line is:

Then the efficiency of the motor is: