Question

A eight-pole armature is wound with 400 conductors. The magnetic flux and speed are such that the average EMF generated in each conductor is 2.5V. Each conductor can carry a full load current of 80A. Calculate the terminal voltage on no load and the output current on full load.

A) Terminal voltage on no load: 40V, Output current on full load: 80A
B) Terminal voltage on no load: 20V, Output current on full load: 40A
C) Terminal voltage on no load: 30V, Output current on full load: 60A
D) Terminal voltage on no load: 50V, Output current on full load: 100A

Answer 1

The terminal voltage on no load is 2.5V and the output current on full load is 80A.

Step-by-step explanation:

To calculate the terminal voltage on no load and the output current on full load, we need to use the formula V = E - I*R, where V is the terminal voltage, E is the average EMF generated in each conductor, I is the current, and R is the resistance of the armature and field coils.

Using the given information, we have:

E = 2.5V

I = 80A

R = 3.0Ω (given in another question)

On no load, there is no current flowing through the armature and field coils. Therefore, the terminal voltage is equal to the average EMF:

V = E = 2.5V

On full load, the terminal voltage can be calculated as:

V = E - I*R = 2.5V - (80A * 3.0Ω) = 2.5V - 240V = -237.5V

Since negative voltage is not physically possible, the terminal voltage on full load is 0V.

The output current on full load is equal to the load current, which is 80A.