Question

A shunt generator has a field resistance of 60 Ω. When the generator delivers 6 kW, the terminal voltage is 120 V, while the generated EMF is 133 V. Determine: a) The armature resistance and b) The generated EMF when the output is 2 kW at a terminal voltage of 135 V.

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Answer 1

Answer:

a) 0.25 ohm

b)139.26 volt

Explanation:

given -

P= 6 kw,

V through terminal =120v

E= 135v

R of field = 60 ohms

a) E =Vt+I*Ra

Ra=E-Vt

I

133-120/52=0.25

Answer 2

The value of armature resistance is 0.0298 Ohm and  the generated EMF when the output is 2 kW at a terminal voltage of 135 V is 139.47V

Given:

A shunt generator has a field resistance of 60 Ω.When the generator delivers 6 kW, the terminal voltage is 120 V, while the generated EMF is 133 V

To Find:

The armature resistance and the generated EMF

Solution:

Armature resistance = 60 ohm

the field current in the winding $I_{f}$ = V/R

= 120/60

= 2A

when the connected load is 60 ohm,

V×$I_{l}$ =60000

$I_{l}$ = 60000/120

= 500A

for a shunt generator the

armature current = load current + field current

Ia = 500+2

= 502A

the generated EMF Eg = V + IR

135 = 120 + 502(Ra)

Ra = 0.0298Ohm

b) When the output is 20 kw and the terminal voltage,

V × I = 20000

I1 = 20000/35

I1 = 148A

If = 20000/135 = 148A

Eg = 135 + 150.25 × 0.0298

Eg = 139.47V

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