A 220V, 5.5 kW, DC shunt generator has an armature resistance of 0.2 Ω and a total field-circuit resistance of 55 W. The generator is supplying rated current at rated terminal voltage. Answer the following questions relating to this generator and explain your choice of answer. (i) What is the generator armature current? 17 A 21 A 25 A 29 A 33 A (ii) What is the armature internal voltage E0? 2 V 2 V 0 V 0 V 8 V (iii) What is the efficiency of the generator if rotational losses are 300 W? 9% 2% 3% 2% 8% (iv) What is the generator voltage regulation if the terminal voltage rises to 222.2 V when the load (only) is reduced by 50%? Assume a linear regulation characteristic for the shunt generator. 5% 1% 2% 5% 10%
Synchronous Generator
In comparison to an asynchronous generator, it is a machine where the rotor speed is equal to the rotating magnetic field produced by the stator, i.e., mechanical speed is equal to the electrical speed, thus called synchronous, and not asynchronous.
Salient Pole Rotor
Salient pole rotor includes a large number of exposed poles mounted on a magnetic wheel. The construction of a bright pole is as shown in the image on the left. The proposed poles are made of metal laminations. The rotor winding is provided on these poles and is supported by pole shoes.
A 220V, 5.5 kW, DC shunt generator has an armature resistance of 0.2 Ω and a total field-circuit resistance of 55 W. The generator is supplying rated current at rated terminal voltage. Answer the following questions relating to this generator and explain your choice of answer.
(i) What is the generator armature current?
- 17 A
- 21 A
- 25 A
- 29 A
- 33 A
(ii) What is the armature internal voltage E0?
- 2 V
- 2 V
- 0 V
- 0 V
- 8 V
(iii) What is the efficiency of the generator if rotational losses are 300 W?
- 9%
- 2%
- 3%
- 2%
- 8%
(iv) What is the generator voltage regulation if the terminal voltage rises to 222.2 V when the load (only) is reduced by 50%? Assume a linear regulation characteristic for the shunt generator.
- 5%
- 1%
- 2%
- 5%
- 10%
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