Question

A series motor has a 230 V supply and draws 108 A when running at 555 rpm. The armature resistance is 0.12 Ω, and the resistance of the series field winding is 0.04 Ω

Calculate the emf generated when the current is 108 A.

a. (a) 220 V
b. (a) 250 V
c. (a) 200 V
d. (a) 275 V

Answer 1

The emf generated when the current is 108 A in a series motor with a 230 V supply, an armature resistance of 0.12 Ω, and a series field winding resistance of 0.04 Ω is approximately 212.72 V.

Step-by-step explanation:

In a series motor, the back emf (E) can be calculated using the formula: E = V - I(Ra + Rf), where V is the supply voltage (230 V), I is the current (108 A), Ra is the armature resistance (0.12 Ω), and Rf is the resistance of the series field winding (0.04 Ω). Plugging in the values, we get: E = 230 - 108(0.12 + 0.04) = 230 - 108(0.16) = 230 - 17.28 = 212.72 V. Therefore, the emf generated when the current is 108 A is approximately 212.72 V.