Difference Between Alternator and Generator

Alternator and Generator are electrical devices used to generate electricity. They have a wide range of applications, from power generation to providing electricity in portable devices. Fundamentally both the devices are the same, but they differ in mode of operation and also have different characteristics.

In this article, we’ll discuss and understand what are Alternators and Generators, their working, and the differences based on various key characteristics.

What is Alternator?

An alternator is a device which converts mechanical energy into alternating current, which can either directly be used or can be first converted to direct current (DC) and stored for later usage. Since it produces alternating current, hence the name alternating current, in alternating current the electrons move forward and backwards constantly, the same type of current is used in our homes for lightning and various electrical appliances, but the voltage is very high.

The alternators can be found inside the car which is responsible for charging the battery and powering various electrical systems in the car such as light, horn, etc. The basic components of an alternator include a rotor, stator, diode rectifier assembly, voltage regulator, and cooling fan.

Working of Alternator

The alternator has a shaft that is connected to the engine of the car via a belt and pulley, when the engine is running the shaft is forced to rotate, and the alternator’s rotor, typically in the form of a coil of wire, rotates within a magnetic field generated by the stator.

This rotation induces an alternating current in the stator windings, but the car uses direct current to run various devices so alternator used a rectifier which converts alternating current into direct current, which is then stored in the battery to power various car operations such as engine turn on, lights etc. The speed of the car is not the same all the time so the current generated is not always same so alternator uses a regulator to maintain a nearly constant output current.

What is Generator?

A generator is a device which converts mechanical energy in direct current or alternating current, where the elector moves in only one direction. Direct Current (DC) is also produced from the battery or cell.

The electric motors produces energy through electromotive induction and is used to generate electricity in power plants. The mechanical energy is generally provided by steam turbines, gas turbines, and wind turbines. Electrical generators provide nearly all the power that is required for electric power grids.

Working of Generator

It operates on the basis of Faraday’s law of electromagnetic induction which states that an electromotive forces (EMF) is produced when a current carrying wire cuts the constant magnetic field lines, and is used to produce electricity in power plants, engines, and various applications where electrical power is required. The mechanical energy supplied to generator forces the movement of electric charges present in the wire of its windings through an external electric circuit.

This flow of electrons constitutes the output electric current supplied by the generator. This movement create an high electromotive force or voltage difference which cause the electric charges to flow, hence generating electric current. It also uses a regulator to maintain a constant output current.

Difference between Alternator and Generator

• Based on work: Alternators convert mechanical energy into AC (alternating current), where as Generators as designed to convert mechanical energy into DC (direct current) or AC
• Based on output type: Alternators produces alternating current, in three-phased power, which are typically out-of-phase with each other, whereas generator produces direct current which are either produces single- phase or multi-phase based on specific type, depending on single voltage or multiple voltage.
• Commutator: The device which ensure the consistent flow of current in one direction, generator uses commutator for rectification of DC power generated, whereas alternators do not use commutator, the output power produced is suitable for use.
• Maintenance: Generator uses commutators and brushes which commonly wear-out , thus require high maintenance than alternators as they do not used commutators etc.
• Efficiency: Alternator are in comparison more efficient in converting mechanical energy to electrical energy as compared to generators.

All the key differences are listed in the following table:

Parameters	Alternator	Generator
Principle of Working	Convert mechanical energy in alternating current.	Convert mechanical energy in direct current or alternating current
Output Produced	Produces alternating current.	Produces direct current or alternating current
Commutator	Does not used any commutator.	Uses a commutator.
Output Voltage	Generally used for high voltage applications.	Can be used for high as well as low voltage applications.
Phases of voltage	Produces three-phase alternating current.	Produces either single-phase or multi -phase direct current based on specific design.
Design	Uses stationary magnetic field and rotating coils.	Have a rotating magnetic field and stationary coils.
Cooling Type	Air-cooled usually.	Can be air or liquid cooled.
Maintenance	Low maintenance	Requires maintenance on regular basis as have wearing out parts.
Usage	Very commonly used in modern times.	Popular in portable dc generation application.
Control	Generally better at voltage regulation.	May have difficulties in regulating voltage.
Power Factor	Have a better power factor.	May have a lower power factor in comparison.
Efficiency	More efficient in comparison in generating electricity.	Less efficient than alternators.
Cost	More cost-effective in comparison.	Can be more expensive because of additional components.
Components	Uses a rotating armature and stationary field windings.	Uses a armature and brushes.
Lifespan	Has a longer lifespan.	Due to wear on brushes and commutator tends to have a shorter life.
Application	Used in modern vehicles and power plants.	Useful in older systems and potable devices.

Application of Alternator and Generator

The applications of Alternator and Generators are mentioned below:

Alternator Applications

• Alternators are used in vehicles to charge battery and to power various electrical systems, including lights, air conditioning etc.
• Alternators are important components in power plants, often driven by various sources of mechanical power such as steam turbines, gas turbines, or diesel engines, to generate electricity.
• Alternators provide power for various machinery and equipment in industries where a stable and reliable power source is necessary.
• Alternators has also been extensively used in agriculture to power tractors.

Generator Applications

• Generators are used in power plants to produce electricity on a large scale for cities, industries, and residential areas.
• They are used as backup or standby power systems in buildings, hospitals, data centers, and for portable applications like RVs, boats, and construction sites.
• Generators power tools and machinery are used at construction sites, remote locations, and mining operations where a power grid connection is not available.
• Generators are used in outdoor events, concerts, and recreational vehicles (RVs) to supply electrical power in remote locations or short period.

Alternator and Generator – FAQs

1. What is Alternator?

An alternator is a device which converts mechanical energy in alternating current.

2. What is Generator?

A generator is a device which converts mechanical energy in direct current.

3. Mention some Common Sources of Large Scale Mechanical Energy.

The common sources of large scale mechanical energy are steam turbines, gas turbines, and wind turbines.

4. What is a Regulator?

Regulator is a device which is used to maintain the voltage of current.

5. What are the Various Components of Electric Generator?

The components of an electric generator are an engine, frame, voltage regulator, cooling system, lubrication system, exhaust system, and a central control panel.

6. What is the Principle of Current Generation in Generator?

It operates on the Faraday’s law of electromagnetic induction which states that an electromotive forces (EMF) is produced when a current carrying wire cuts the constant magnetic field lines.