Correct Answer - Option 1 : separately excited type DC generator
Applications of Separately Excited DC Generators:
This type of DC generator is generally more expensive than self-excited DC generators because of their requirement of separate excitation sources. Because of that, their applications are restricted. They are generally used where the use of self-excited generators is unsatisfactory.
- Because of their ability to give a wide range of voltage output, they are generally used for testing purposes in laboratories.
- Separately excited generators operate in a stable condition with any variation in field excitation. Because of this property, they are used as supply sources of DC motors, whose speeds are to be controlled for various applications. For example Ward Leonard Systems of speed control.
- Used in power and lighting purpose with the help of field regulators
Compound Wound DC Generators:
- Among various types of DC generators, the compound wound DC generators are most widely used because of their compensating property.
- Depending upon the number of series field turns, the cumulatively compounded generators may be over compounded, flat compounded, and under compounded.
- We can get desired terminal voltage by compensating the drop due to armature reaction and ohmic drop in the line.
Applications:
- Over Compound DC Generators are generally used for lighting, power supply purpose, and for heavy power services such as feeding long DC transmission lines.
- Cumulative compound wound generators are also used for driving a motor.
- Flat compounded generators are generally used for small distance operations, such as power supply for hotels, offices, homes, and lodges.
- The differential compound wound generators, because of their large demagnetization armature reaction, are used for arc welding where huge voltage drop and constant current are required.
Applications of Shunt Wound DC Generators:
The application of shunt generators is very much restricted for its dropping voltage characteristic. They are used to supply power to the apparatus situated very close to its position. These types of DC generators generally give constant terminal voltage for small distance operation with the help of field regulators from no load to full load and employed for various applications such as:
- They are used for general lighting.
- They are used for battery charging because they can be made to give constant output voltage.
- They are used for giving the excitation to the alternators.
- They are also used for small power supply (such as a portable generator).
Applications of Series Wound DC Generators:
These types of generators are restricted for the use of power supply because of their increasing terminal voltage characteristic with the increase in load current from no load to full load. They give constant current in the dropping portion of the characteristic curve. For this property, they can be used as a constant current source and employed for various applications such as:
- They are used for supplying field excitation current in DC locomotives for regenerative braking.
- These types of generators are used as boosters to compensate for the voltage drop in the feeder in various types of distribution systems such as railway service.
- In series arc lightening this type of generator is mainly used.
