Correct equation of speed-torque characteristic of DC shunt motor

correct-equation-of-speed-torque-characteristic-of-dc-shunt-motor

Correct equation of speed-torque characteristic of DC shunt motor is____________

I got this question in an interview.

This intriguing question originated from Operating Characteristics of DC Shunt Motor topic in section Characteristics of DC Motors of DC Machines

Right choice is A. [Vt / kΦ] – [Ra / kl Φ2] T

To elaborate: Speed-torque characteristic equation is obtained by n = (Vt -IaRa)/ kφ and Torque = k1φIa. Thus, by combining these equations and by assuming all constants equal to k and kl we get the final equation shown above.