What is an alternator and how does it work?

What is an alternator and how does it work?-Do you know what is Alternator (What is Alternator )? Where is it used, what are its different types? There are many such questions that often arise in the mind. If you have a car, that means there is a car, then you must have probably heard about this word Alternator.

This is because it is used to charge the battery while moving in cars or any other large vehicle. This alternator’s job is to convert mechanical energy into electrical energy. And therefore it comes in handy to convert the mechanical energy being generated in such a car into electrical energy while driving.

As difficult as it sounds, it is not that difficult. That’s why today I thought that why should you be given information about some important questions like what is an alternator and how it works, what are its components, so that you can answer all the questions arising in your mind while reading this article.

What is Alternator

Alternator is a type of electrical machine that converts mechanical energy into alternating electric energy. Therefore it is also called synchronous generators or AC generators.

What is an alternator and how does it work?
What is an alternator and how does it work?

If you have a car or a heavy and big vehicle, then if your headlights are a bit dim, and your car is not starting always. And you are worried because what is the reason for this, then maybe the reason for this can also be a malfunction of the alternator, because this small piece of machinery is very useful for you, which generates electricity from mechanical energy. Also Alternators are your vehicles. It also charges the battery when you are driving it. If they are not working then your battery will slowly die.

Your car needs a lot of power to start up and work, and if your battery is not getting recharged, it will easily die very soon. That’s why Alternator has a very important job in any vechile.

Mechanical Energy and Electrical Energy

Mechanical energy is called that type of energy which is possessed by an object due to its movement or its position. The engine of your car is made up of many parts, in which there is also a thing called crankshaft.

This crankshaft rotates when the engine is running. This rotation produces a type of energy which is called mechanical energy, and this is passed to the alternator.

Then this alternator takes this mechanical energy and converts it into electrical energy, this is the same energy that comes from electric charge. Typically, the alternator produces alternating current, or AC.

As the name suggests, this electrical current alternates or keeps switching directions. In contrast, there is direct current, or DC, where electrical current flows in only one direction.

The current used in your home, office, and outlets is AC current, because it is easy to move from one place to another and it also provides more voltage.

At the same time, some of our devices such as cellphones, items that use batteries, and flat-screen TVs use DC. You must be wondering how DC is given to these devices, then the answer is that you can use these devices in AC outlets but for this you have to use AC adapter or a USB cable.

History of the alternator

Hippolyte Pixxi and Michael Faraday first brought the concept of alternator. He designed a rectangular rotating conductor inside a magnetic field so that it could generate alternating current for the outer static circuit.

J.E.H. Gordon designed and produced a similar model in 1886, which was its first prototype. A model which was a 100 to 300 Hz synchronous generator was designed by Kelvin and Sebastin Ferranti.

Whereas in 1891, Nikola Tesla built a commercially useful 15 Khz generator. Poly phase alternators became commercialized a few years after that, which have the ability to provide multiple phase currents.

What are the main components of an alternator?

Alternator is a very important part of any vehicle. Which maintains the battery of the car, provides power to the lights, as well as works for the heater and other accessories.

It works like a generator and produces electricity like a turbine system. The 12-volt battery of the car has enough charge so that the car can be started.

Whereas without an alternator, the battery cannot be recharged easily, but without it it has to be manually charged every time you restart the car. If seen, there are many main components of the alternator which do their own work. Let us know more about these components.


Alternators use electromagnets to create a magnetic field. Electromagnets use wire that is wrapped around a metal piece. When an electrical current goes through that wire, then that piece of metal becomes magnetized.

Before this, let us understand about some words which are associated with magnets. Magnetic field is called that field which is created around magnetic substances. A magnetic substance is a type of material in which the electrons are oriented in such a way that it can attract other metals. What does electron oriented mean?

You must be aware that all things are made up of tiny particles called atoms. The electrons in atoms are spinning outside the nucleus. Electrons are like tiny magnets. These electrons always spin in the same direction and that too in a certain way.

Actually all these are spinning differently, but since then the substances are not magnetic. And when they orient in the same direction, then they behave like a magnet.

In an electromagnet, when electrical current passes through the wire, it orients the electrons of the metal in the same direction, and you get a magnet.

Alternator Rotor

Rotor, it is made of iron core around which there is winding of copper wire. When an electrical charge is introduced into the wire, it magnetizes that iron core (electromagnet).

These electrical currents come from brushes that come in contact with metal rings. Speaking specifically, these metal rings are called slip rings, and they are usually made of copper.

As the rotor spins (think rotor = rotation), then these slip rings come in contact with the brushes which are made of carbon. This contact creates an electrical charge, and the charge travels through the winding copper wire, and it creates an electromagnet.


You just learned about the rotation, or spins, of a rotor. It is actually spinning inside the stator, which is an iron core that surrounds three coils. It is easy to differentiate these two from each other where the rotor rotates while the stator is stationary.

This allows the crankshaft drive belt to rotate easily, thereby turning on the rotor located inside the stator. This is the mechanical energy I talked about at the beginning of the lesson.

Rotor and Stator

These rotor and stator are belt-driven group of magnets of an alternator which are inside the copper wiring and they create a magnetic field. This belt is driven by a pulley that is connected to the engine, and which allows the rotor to spin at high-speed, creating a magnetic field.

Then the stator produces voltage and electricity which flows into the diode assembly. The electricity generated in this is alternate current, or AC.

Diode Assembly

The diode assembly of an alternator converts AC electricity into direct current, or DC, which is the current type used in car batteries. This diode assembly is a two-terminal system, which works only in the electricity which is produced in the stator and for it to flow in only one dirction.

Voltage Regulator

This voltage regulator is the surge protector of the alternator. Modern voltage regulators, which are internal systems, monitor both the alternator and battery voltage, adjusting the current only as needed. Older voltage regulators are mounted externally.

Parts of Alternator Motor

Now let’s know more about the parts of Alternator Motor.

Diode Rectifier

This diode rectifier, also called rectifier bridge, is responsible for converting alternating current into direct current with the help of an alternator. Most automobile alternators have six diodes. This part is like a translator between rotor, stator and battery.

Rotor Assembly

A rotor assembly is made up of many parts. Its main part is an iron core, around which the wires (field windings) are wound. There are finger poles around the core and windings, which are placed with alternating north and south charges. As the rotor spins, alternating finger poles create a magnetic field around the iron core.

Admittedly, the core, windings, and poles are very important parts of the rotor assembly, whereas there are other things in the rotor assembly such as a cooling fan, slip rings, brushes, and bearings. They are responsible for directing the current towards the winding, thereby protecting the alternator from overheating, and helping in the proper movement of the main assembly parts.

How does an AC Generator work?

The basic working principle of an Atlernator or AC generator is the same as that of a DC generator. According to Faraday’s law of electromagnetic induction, whenever a conductor moves in a magnetic field, EMF is induced across the conductor.

If close path is provided to the conductor, then this induced emf forces the current to flow in the circuit.

For example, when a conductor coil ABCD is placed in a magnetic field. Then the direction of magnetic flux will be from N pole to S pole. Then the coil will be connected to the slip rings, and the load will be connected to the brushes which will rest in the slip rings.

If the coil will rotate clockwise, then the direction of the induced current in this case will be according to Fleming’s right-hand rule, and it will be along A-B-C-D.

Because the coil is rotating clockwise, so after half of the time period, the position of the coil will be somewhat different. In this case, the direction of the induced current will be according to Fleming’s right-hand rule along D-C-B-A. This shows that the direction of the current changes after a half-time period, which means we get an alternating current.

Why Armature’s Winding Stationary is there in Alternator?

  • In high voltages, it is easy to insulate the stationary armature winding, which can be as high as 30 kV and even more.
  • This high voltage output can be easily taken out directly from the stationary armature. Whereas in a rotary armature, this is not so simple because a large brush contact drops into it at higher voltages, as well as sparking the brush surface.
  • The field exciter winding is placed in the rotor, and the low dc voltage can be transferred easily and safely.
  • In this, the armature winding is braced well, so that it can prevent the deformation caused by the high centrifugal force.

Types of Alternators

Alternator is also called synchronous generator. They are divided according to their application and their design. Let us know about some types.

  1. Automotive type – These are used in modern automobiles.
  2. Diesel-electric locomotive type – These are used in diesel-electric multiple units.
  3. Marine type – They are used in marine.
  4. Brushless type – They are used according to the main source of power in the electrical power generation plant.
  5. Radio alternators – These are used in low brand radio frequency transmission.
  6. Salient pole type.
  7. Cylindrical rotor type.

What are the Classifications of Alternators ?

There are so many types of Atlernator that they are classified into different categories. Let us get some information about its different categories below.

Based on output power

  1. Single Phase
  2. Three Phase

Based on the working principle

  1. Revolving armature type
  2. Revolving field type

Based on the speed on rotation

  1. Turbo alternator
  2. Low speed alternator

Based on coiling

  1. Air cooling
  2. Hydrogen cooling

What is the difference between Alternator and Generator?

Alternators and generators, both these devices are used to generate electricity. An alternator is actually a type of generator. It cannot be denied that both these devices have similar functions, but in all other aspects they are different from each other.

Alternator is a type of charging system of cars which produces electricity which is in small scale. Whereas Generators are used for large-scale electricity production.

Both alternators and generators are used to convert mechanical energy into electrical energy. But the main difference between these two is in its spinning.

In an alternator, electricity is produced when a magnetic field spins inside the stator (which are the windings of wire). Whereas in a generator, the armature or windings of wire spin within a fixed magnetic field from which electricity is generated.

Alternators are considered to be more efficient than generators. This is because alternators conserve excess energy and use only the energy needed, whereas generators use up all the energy that is produced.

Therefore, alternators have a higher output than generators. When it comes to polarization, it is different between alternators and generators. Where generators are polarized after installation, polarization is not required in alternators.

Alternator brushes last longer than generators. This is because in an alternator brushes are used only to power the rotor to carry current and in slip rings which make the ride smooth.

They also work differently in charging. Where an alternator cannot charge a dead battery and it can also burn out on charging. While a generator, but a dead battery can be used for charging.

Talking about the size, the Alternator requires very little space to fit but while the Generators require a large space.

What does the alternator do

Do you know what the alternator produces? Modern vehicles and electrical systems get their power from the alternator.

In the old days, DC generators or dynamos were used for a specific purpose. After alternator development, these are more robust and light weight alternators which are used as replacement of DC dynamos.

Still a general requirement for motor vehicles with direct current and it is still an alternator with a rectifier diode, in place of a DC generator, it is a better choice as it does not involve complicated communication. Is.

Another use of the diesel electric locomotive is the alternator. Alternator which is driven by a diesel engine, it is an engine of the locomotive. DC is converted to AC which is produced from the generator and is integrated into the silicon diode rectifiers which feed all the DC traction motors.

It is also used in marine like diesel electric locomotive. It has been designed in such a way that its synchronous generator is used in marine so that it can easily face the salt-water environment. 12 or 24 volt is the output level of the marine alternator. Power is generated by the alternator in the marine system, it is first rectified by charging the engine battery starter and this battery supply is helpful in a way for marine.

What are the Advantages and Disadvantages of Alternators

If I tell you something old, in the late 1800s, Nikola Tesla and George Westinghouse made a case against Thomas Edison that the United States’ electric plants should generate alternating current (A/C) or direct current (D/C).

Where Tesla developed 40 patents in A/C technology, which was purchased by Westinghouse. Whereas Edison did not want to lose his D/C royalties, and he promoted D/C technology only, but later he had to give up because A/C’s superiority is much higher than D/C current.

Let us know more about the advantages and disadvantages of both these currents.

There is no need to do Matching Voltage in this
A D/C generator has to produce the same level of voltage in which it can be used. A/C however has the advantage that it allows you to convert the current to a different voltage by using a transformer. Transformers work only in A/C and not in D/C.

They Can Travel Longer Distances
Traveling longer distances in A/C does not result in more loss of power as compared to D/C. By converting the current into high voltage, it reduces the current, thereby reducing the power loss. This can be understood from the formula P=R*I-squared, where P is power loss due to resistance, R is resistance, and I is current. Since I is squared in this power formula, so by decreasing I a bit (by increasing the voltage), it earns a lot of power loss.

Transformer Requirement
A/C generators have a disadvantage that they require transformers, which complicates the circuitry. They have to be designed in such a way that the higher voltage does not discharge (arc) one side.

High voltages are not generated efficiently, so low voltages are generated and the voltage is transformed into a higher level for long-distance transmission.

Another safety-related disadvantage is that there is a danger of electric shock in A/C because higher voltage is used for long-distance transmission. This is especially because in long-distance transmissions, the power lines are placed high above the ground.

125k Va Kirloskar Old Model Alternator Diode Light Price?

The price of this model from Kirloskar ranges from Rs.30,000 to Rs.50,000.

Can a 5kva Alternator be powered by a Maruti 800?

The alternator output of the Maruti 800 should range from 13.5 to 14.5 V.

Where to get tractor operated alternator 15 kv second hand in Bhopal?

Bhopal is a very big city, so there are many shops in it and in such a situation, almost all the goods are available in everyone like tractor alternator etc. You should look for any good shop near you.

Alternator में दोनों Brushes में साथ Electric संपर्क बनाई है?

Alternator में brushes को लेकर काफी problem आती है. ऐसा इसलिए क्यूंकि alternator के भी एक finite life होती है लेकिन इसकी life को बढ़ाने के लिए आपको rotating belt का ख़ास ख्याल रखना चाहिए जैसे की ये ज्यादा tight नहीं होना चाहिए और न ही ज्यादा ढीला.

Why are capacitors not installed in the alternator?

The capacitor is not put in the alternator because by applying it, it will overload the alternator because there will be extra watt consumer in it, due to the capacitor.

Full details of alternator

I hope that I have given you complete information about What is an alternator and how does it work? and I hope that you have understood about the work of an alternator.

If you have any doubts about this article or you want that there should be some improvement in it, then you can write low comments for this. From these thoughts of yours, we will get a chance to learn something and improve something.

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