Difference Between AC And DC Generators

Comparisons, Knowledgebase

Last Updated on November 25, 2022 by mdmtool

AC and DC generators both produce electricity. DC generators use direct current to produce electricity, while AC generators use alternating current. This means that DC generators can generate a constant flow of electricity, while AC generators can generate an electric current that alternates direction.

What Is An AC Generator?

what is ac generator

An AC generator is an electrical machine that converts mechanical energy into alternating current (AC) electrical energy. The basic principle of an AC generator is similar to that of a DC generator. However, in an AC generator, the armature winding is connected to the external circuit through slip rings and brushes instead of being directly connected as in a DC generator.

What Is A DC Generator?

dc generator

A DC generator is an electrical machine that converts mechanical energy into direct current (DC) electricity. The most common type of DC generator is the brushed DC motor.

A DC generator works by using magnets to create a magnetic field and then using that magnetic field to generate electricity. The north and south poles of the magnets create opposing magnetic fields. When these fields interact, they create a force that rotates the armature, which is connected to the generator’s shaft.

Types Of AC Generators

differnece of ac dn generator

  • Induction generators: These generators work on the principle of electromagnetic induction. When the flux in the stator winding is rotated, an induced emf is set up in the rotor winding.
  • Synchronous generators: These generators work on the principle of electromagnetic induction. When the flux in the stator winding is rotated, an induced emf is set up in the rotor winding. This induced emf sets up a rotor winding current, producing a magnetic field.
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Types Of DC Generators

There are three types of DC generators:

  • Shunt-wound: In a shunt-wound DC generator, the field winding is connected in parallel with the armature winding.
  • Series wound: In a series wound DC generator, the field winding is associated with the armature winding.
  • Compound wound: In a compound wound DC generator, the field winding is connected in parallel and series with the armature winding.

What Are The Differences Between AC And DC Generators?

  • The Design and Mechanism: An AC generator has a commutator-less winding arrangement. The armature is directly coupled to the field winding, resulting in a more compact design. A DC generator has a commutator and brush-type arrangement.
  • Use and Maintenance: An AC generator is used in various applications, including wind turbines, hydroelectric power plants, and internal combustion engines. A DC generator is mainly used in automobile applications.
  • Connectivity: An AC generator can be connected to an AC load directly. A DC generator needs a rectifier to convert the DC output to AC before joining it to an AC load.
  • Powered: Another significant difference between AC and DC generators is how they are powered. DC generators are powered by batteries, while AC generators are powered by an external power source such as a generator or the electric grid.
  • Transformation: The main advantage of an AC generator over a DC generator is that the AC can be easily transformed to any desired voltage level using a transformer, which is impossible with a DC generator.

DC Generators Advantages

  • They are very simple and rugged in construction.
  • They have no commutator and brushes hence maintenance free.-They can be operated at any speed.
  • They can be used for variable loads.
  • They have high power density.
  • They are more efficient than AC generators.
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AC Generators Advantages

  • They are very efficient.
  • They are easy to maintain.
  • They have a long lifespan.
  • They can be used for variable loads.
  • They can be operated at any speed

AC Generators Disadvantages

  • They are more expensive to maintain and repair than DC generators and that they require more frequent maintenance.
  • AC generators produce alternating current, they cannot be used to directly power most devices and must be converted to DC before they can be used.

DC Generator Disadvantages

  • DC generators require more frequent maintenance.
  • DC  generators and may not be able to produce as much power.

How To Convert An AC Generator Into A DC Generator?

An AC generator can be converted into a DC generator by adding a commutator. A commutator is an electrical switch that reverses the electric circuit’s current direction. It is used in DC generators to change the current flow through the armature coil each time the coil reaches the positive or negative peak of the magnetic field. This keeps the current flowing in one direction, allowing DC to be generated.

Which One Is Better: An AC Generator Or A DC Generator?

AC generators are typically more efficient than DC generators, which makes them a better choice for large-scale power generation. However, DC generators can be more efficient than AC.


Why is an AC generator used over a DC generator?

The main reason AC generators are used rather than DC  generators is that they are much more efficient. AC generators can produce higher voltages than DC generators, meaning they can transmit power over long distances with less loss.


AC generators are more efficient than DC generators and can produce more electricity per unit of fuel. This is because AC generators can convert more energy from the power into electricity, while DC generators convert less energy into electricity. This makes AC generators the preferred choice for applications where a large amount of electricity is needed.

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