What is Difference Between Dynamo and Generator ?

Fig: Basic idea of DC & AC generator

What is the difference between a Dynamo and a Generator?

Dynamo- One of the simplest and earliest electrical generators, used to generate electrical power for industry. Dynamos were quickly replaced by other electrical generators because of the advantages of Alternating Current (AC).

The question is actually a bit confusing because the generator can be divided into two: one is a DC generator, and the other is an AC generator or Alternator.

So if you mean alternator by generator, then maybe the difference can be made that a dynamo produces DC current and an alternator produces AC current.

And if the dynamo means DC and the generator means the alternator-dynamo together, then…

Dynamo is the kind of system that can only produce DC current. The generator AC current can be converted to DC via a commutator.


The dynamo is actually the old state of the generator of the era. Alternator generators are now used throughout the world. Although there are times when low power DC flow is required where dynamo is still used.

Today, Dynamo means DC (Direct Current) generator, and Generator means alternator or AC generator. Further details, a DC generator generates AC current, but it contains a simple device called a commutator to convert AC into DC. A commutator diverts the flow of electrons inside the DC generator, so that the energy that appears at the output is a pulsing direct flow. On the other hand, an AC generator does not need a commutator, and it generates AC directly. Dynamos and Generators both convert mechanical rotation, like wind, hydro, gas, waves, etc., into electrical power.

Thomas Edison believed that the base of future electricity would be DC, but Nikola Tesla believed in AC. Finally, Nikola Tesla proved he was correct.


Early people used batteries for electricity, but batteries were not reliable and cost-effective. However, the Dynamo rapidly changed into a profitable and reliable technology for electricity.
A 
Dynamo or Generator is made up of a stator or stationary magnets which create a powerful magnetic field, and a Rotor or rotating magnet which distorts and cuts through the magnetic lines of flux of the stator. When the rotor cuts through lines of magnetic flux, it makes electricity.

Short History of Dynamos and Generators

In 1820, Michael Faraday and Joseph Henry first discovered and prepared some documents on electromagnetic induction. The Faraday Disk is the first electric generator, which shows that rotary mechanical power can be converted into electric power. The electric power generation race started from here; later on, this led to experimentation in Europe and America about Dynamos/Generators.

1832, Hippolyte Pixii & Ampère built the first hand-cranked dynamo using a commutator. Latter on 1860, Antonio Pacinotti created a dynamo that provided continuous DC power. H Wilde made the commercially successful Alliance generator in 1866 for powering arc lamps in lighthouses. All of these generators employed permanent magnets.

Instead of a weak permanent magnet dynamo/generator, a more powerful self-powered electromagnet in the stator was invented by Werner Von Siemens and Charles Wheatstone in 1867. The commercial revolution of electricity generation was achieved by Zenobe Gramme in 1871; he used an iron core to give an improved and efficient path for magnetic flux, which increased the power of the dynamo/generator and make wide usable for many commercial applications.


The best system for power generation, a 3-phase AC generator developed during 1886 to 1891, many scientist /engineer from the USA, Germany, Russia, and Italy worked to improve the generator.

What is the Characteristics of DC Generator?

A dc generator is an electrical machine which converts mechanical energy into direct current electricity. This energy conversion is based on the principle of production of dynamically induced emf. This article outlines basic construction and working of a DC generator. 

The above figure shows the constructional details of a simple 4-pole DC machine. A DC machine consists two basic parts; stator and rotor. Basic constructional parts of a DC machine are described below.

Yoke

The outer frame of a dc machine is called as yoke. It is made up of cast iron or steel. It not only provides mechanical strength to the whole assembly but also carries the magnetic flux produced by the field winding.

Poles and pole shoes

Poles are joined to the yoke with the help of bolts or welding. They carry field winding and pole shoes are fastened to them. Pole shoes serve two purposes; (i) they support field coils and (ii) spread out the flux in air gap uniformly.

Field winding

They are usually made of copper. Field coils are former wound and placed on each pole and are connected in series. They are wound in such a way that, when energized, they form alternate North and South poles.

Armature core

Armature core is the rotor of the machine. It is cylindrical in shape with slots to carry armature winding. The armature is built up of thin laminated circular steel disks for reducing eddy current losses. It may be provided with air ducts for the axial air flow for cooling purposes. Armature is keyed to the shaft.

Armature winding

It is usually a former wound copper coil which rests in armature slots. The armature conductors are insulated from each other and also from the armature core. Armature winding can be wound by one of the two methods; lap winding or wave winding. Double layer lap or wave wingdings are generally used. A double layer winding means that each armature slot will carry two different coils.

Commutator and brushes

Physical connection to the armature winding is made through a commutator-brush arrangement. The function of a commutator, in a dc generator, is to collect the current generated in armature conductors. Whereas, in case of a dc motor, commutator helps in providing current to the armature conductors. A commutator consists of a set of copper segments which are insulated from each other. 

The number of segments is equal to the number of armature coils. Each segment is connected to an armature coil and the commutator is keyed to the shaft. Brushes are usually made from carbon or graphite. They rest on commutator segments and slide on the segments when the commutator rotates keeping the physical contact to collect or supply the current.