Question

Give three reasons for the drop in voltage of the Shunt Generator with increasing load??

Answer 1

In shunt generator, both armature and field winding are connected in parallel.

V=E-Ia*Ra

Where, V= terminal voltage

E= generated voltage = (phi)ZNP/(60*A)

Ia= armature current

Ra= armature resistance

1.Armature resistance drop:

Increase in load means increase in load current. So, armature current increase while increasing the load. This increase armature voltage drop (Ia*Ra). This decreases the terminal voltage.

2. Armature reaction:

The effect of armature flux on the main field flux is called as armature reaction. Generated voltage is directly proportional to flux. While increasing load, armature current increases. That causes armature flux increases. Due to this armature reaction, flux decreases. That causes the generated voltage decreases. This implies terminal voltage decreases.

3. Field weakening due to armature reaction and armature voltage drop.