Difference Between AC and DC Generator

Difference between AC and DC generator is one of the most discussed topics among the physics enthusiasts. In this article, the main differences between AC and DC generator in tabular form are given in a simple and easy to understand way. These AC and DC generator differences can help the students learn about this topic better and remember the points more effectively.

Difference Between AC and DC Generator

Before going to the differences, it is important to learn about AC generators and DC generators in detail. By knowing their details, understanding the differences will become easy and simple. Check about AC and DC generators from the links given below.

Difference Between AC and DC Generator

Sl. No.

Differentiating Property

AC Generator

DC Generator



AC generator is a mechanical device which converts mechanical energy into AC electrical power.

DC generator is a mechanical device which converts mechanical energy into DC electrical power.


Direction of Current

In an AC generator, the electrical current reverses direction periodically.

In a DC generator, the electrical current flows only in one direction.


Basic Design

In an AC generator, the coil through which the current flows is fixed while the magnet moves. The construction is simple and costs are less.

In a DC generator, the coil through which the current flows rotates in a fixed field. The overall design is very simple but construction is complex due commutators and slip rings.



AC generator does not have commutators.

DC generators have commutators to make the current flow in one direction only.



AC generators have slip-rings.

DC generators have split-ring commutators.


Efficiency of Brushes

Since slip-rings have a smooth and uninterrupted surface, they do not wear quickly and are highly efficient.

Both brushes and commutators of a DC generator wear out quickly and thus are less efficient.


Short Circuit Possibility

As the brushes have high efficiency, a short circuit is very unlikely.

Since the brushes and commutators wear out quickly, sparking and short circuit possibility is high.



In case of AC generators, the armature is always the rotor.

In case of DC generators, the armature may be either rotor or stator.


Rotating Parts

The rotating part in an AC Generator is low current high resistivity rotor.

The rotating part in a DC generator is generally heavy.


Current Induction

In AC generator, the output current can be either induced in the stator or in the rotor.

In DC generator, the output current can only be induced in the rotor.


Output Voltage

AC generators produce a high voltage which varies in amplitude and time. The output frequency varies (mostly 50Hz to 60Hz).

DC generators produce a low voltage when compared to AC generator which is constant in amplitude and time i.e. output frequency is zero.



AC generators require very less maintenance and are highly reliable.

DC generators require frequent maintenance and are less reliable.



AC generators can of varying types like 3 Phase generators, Single phase generators, synchronous generator, induction generator, etc.

DC generators are mainly two types which are Separately excited DC generator and Self-excited DC generator. According to field and armature connection, they can be further classified as DC series, shunt or compound generators respectively.



The initial cost of AC generator is high.

The initial cost of DC generator is less when compared to AC generators.


Distribution and Transmission

The output from AC generators is easy to distribute using a transformer.

The output from DC generators is difficult to distribute as transformers cannot be used.



AC generators are very efficient as the energy losses are less.

DC generators are less efficient due to sparking and other losses like copper, eddy current, mechanical and hysteresis losses.



It is used to power for smaller motors and electrical appliances at homes (mixers, vacuum cleaners, etc.)

DC generators power very large electric motors like those needed for subway systems.

These were the main AC and DC generator differences. In the above difference between DC and AC generator, several higher level concepts are also included to give in-depth insights about the DC and AC generators. This is extremely important for the students wishing to pursue engineering (especially electrical).

Apart from these differences, students can also check additional related articles given below. The additional related articles can help to learn similar topics in a better and more effective way. Click the links given below for more related articles.

Also Check:

Alternating Current (AC) and Direct Current (DC)

Electric Generator

The Electric Motor

Electromagnetic Induction

Stay tuned with BYJU’S to get more such articles on differences and on other important physics topics.

Practise This Question

If x=sin 130 cos 80, y=sin 80 cos 130, z=1+xy,
which one of the following is true