Question

A shunt-connected D.C machine driven by a diesel engine supplies a current of 25A to a eeo 110v battery. The armature and field resistances are 0.52 and 1102 respectively, and friction, windage and other losses total 220W. Calculate

a. The generated e.m.f,
b. Efficiency

Answer 1

The generated e.m.f is 122V and the efficiency is 92.7% for the shunt-connected D.C machine driven by a diesel engine supplying a current of 25A to a 110V battery.

Step-by-step explanation:

First, let's calculate the generated electromotive force (e.m.f) of the shunt-connected D.C machine. The generated e.m.f can be found using the formula:

e.m.f = V + Ia * Ra

Where V is the voltage supplied to the battery (110V), Ia is the armature current (25A), and Ra is the armature resistance (0.52).

Plugging in the values, we get:

e.m.f = 110 + (25 * 0.52) = 122V

To calculate the efficiency, we can use the formula:

Efficiency = (Useful power output / Total power input) * 100%

The useful power output can be found by subtracting the losses from the generated power. The total power input can be found by multiplying the generated e.m.f by the armature current. Let's calculate:

Useful power output = Generated e.m.f * Armature current = 122 * 25 = 3050W

Total power input = Generated e.m.f * Armature current + Losses = 122 * 25 + 220 = 3295W

Now, we can calculate the efficiency:

Efficiency = (3050 / 3295) * 100% = 92.7%