A short shunt compound generator supplies a load current of 100 A at 250 V. The generator has the following winding resistances: shunt field = 130Ω, Armature 0.1 Ω and series field = 0.1 Ω . Find the Emf generated if the brush drop is 1 V per brush.
A short shunt compound generator supplies a load current of 100 A at 250 V. The generator has the following winding resistances:
shunt field = 130Ω, Armature 0.1 Ω and series field = 0.1 Ω . Find the Emf generated if the brush drop is 1 V per brush.
Right Answer is:
272.2 V
SOLUTION
Voltage = 250 V
Load current (IL) = 100 A
Shunt field (Rf) = 130Ω
Armature field (Ra) = 0.1Ω
Series field (Rse) = 0.1Ω
Brush voltage Drop = 1V
Now voltage drop in the field winding = ILRse
= 100 x 0.1 = 10 V
For short shunt compound generator, the voltage drop across series field winding gets added with voltage drop across armature winding
Voltage drop across field winding + Voltage drop across armature winding
V1 = 250 + 10 = 260 V
Field current If = V1/Rf = 260/130 = 2 A
So armature current
Ia = IL + If = 100 + 2 = 102 A
Generated EMF
E = V1 + IaRa
= 260 + 102 × 0.1
E = 270.2 Volt