What Are the Main Types of Generators in Physics?
There was a time when the battery was the only method for deriving electricity. However, it was costly.
To replace this method, nowadays, people install a device outside their homes to utilize electricity whenever there is a power cut.
What is that device people utilize to get electricity?
Well, this device is the generator.
A generator is a device that takes energy from the source and converts it into electrical energy.
When we provide a torque to the generator, it continues to rotate.
So, rotational mechanics occur because of mechanical energy. Due to this motion, we get electricity.
It works on the principle of conservation of energy.
According to the conservation of energy, the generator doesn’t produce energy; it only transforms one form of energy into another.
Principle of a Generator
A generator works on the principle of electromagnetic induction (EMI).
What is EMI?
Suppose a closed coil is placed between the N and the S pole as shown below:
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If we look at the above diagram, the magnetic field lines pass from the North to the South pole.
As the coil rotates, the number of magnetic field lines crossing this coil varies.
Because of the change in the number of magnetic field lines during the rotation of the coil, electricity generates. This phenomenon is called EMI.
Induced Current
EMI is an interesting phenomenon in physics. It states that if we keep on changing the number of magnetic field lines, neither increase nor decrease them, a type of current, a generator, produces the induced current.
So, what does induced mean?
The word induced means intangible.
The induced current is also intangible because we don’t touch the coil, only the varying magnetic field lines passing through the rotating coil, and we are getting electricity.
Now, let’s talk about the different types of Generators.
Types of Generators
There are mainly three types of Electric Generators (or the types of power generators) that are outlined:
Portable Generators
Inverter Generators
Standby Generators
The common types of Generators are:
Gasoline Generators
Diesel Fuel Generators
Propane Gas or Vapor Generators
Biodiesel Generators
Emulsified Diesel Generators
Natural Gas Generators
Hydrogen Generator
Now, let’s discuss these one-by-one
Portable Generators
If you wish to use a generator that is light-weight, safe to use, reliable, and soundproof, and outdoor enthusiasts, then installing portable generators outside is the best choice for you.
These residential generators are diesel-powered devices that provide temporary electrical power.
We use them to fulfill our essential home power needs during power-outages, for powering cabin appliances, or for power tools needed during projects.
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Inverter Generators
If you prefer the output on low energy emissions and a small, quiet working device, then installing the inverter generator would be the first choice.
An inverter generator electronically controls the movement of the engine to fulfill electricity demand instead of running full tilt all the time.
The best part of using such a device is that you don’t have to fill up the gas tank frequently.
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Standby Generator
If you wish to use a device that has the following features:
Worry-free, i.e., you don’t need to refill for weeks for its functioning.
Runs automatically
Sized to power an entire house in the event of an outage
An electrical back up system
Then installing a standby generator would be best for you.
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Diesel standby generator
Gasoline Generators
It is one of the best generators because it runs on gasoline and is easily available at low-cost.
These generators are available in small sizes; they are ideal for power models.
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The Demerits of using this device are:
They generate high emissions
Gasoline is unavailable during power outages because it requires electricity to pump.
They don’t start well in cold weather.
Diesel Fuel Generators
Diesel is the least flammable of all the fuel sources and is easily available.
Merits
Have a long lifespan
They perform efficiently for a long time under proper maintenance.
Affordable to operate
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Demerits
Diesel fuel is good only up to 24 months of storage, and storing large quantities is expensive.
Produce high emissions
Costlier than gas engines.
Propane (vapor and liquid) Generators
These generators have the following features:
Produces low emissions
They boast a longer shelf life than diesel and gasoline generators
Burn cleanly
Can be easily stored in any quantity
Readily available in power outages
Affordable, and long-lasting
Starts easily in cold temperatures
Quiet operation
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Demerit
Propane is kept under pressure because it is highly inflammable, even explosive.
Biodiesel Generators
Biodiesel is made by the mixture of diesel and from biological sources, such as vegetable oil or animal fat.
Merits
They require lesser fossil fuels
Burn with lower emissions and leaves less residue
Environment-friendly
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Demerits
Unavailable during power outages.
Emulsified Diesel Generators
It is a mixture of diesel fuel and water blended with a mixing agent.
Merits
Consumes less fossil fuel and produces lower emissions
Demerits
Maintaining a proper diesel to water ratio is a challenging task.
Natural Gas Generators
Natural gas has a limitless supply.
Merits
Natural gas is supplied continuously during their operations that these generators never run out of fuel or require refilling
They are quiet at operating
Burns cleanly with lowe emissions
Starts well in cold conditions
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Demerit
Include high installation costs for a continuous supply of natural gas.
Hydrogen Generator
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These generators use hydrogen because:
It is tremendously abundant (particularly from water sources),
Non-toxic,
Clean,
Cheap, and
Generates more energy per pound than any other fuel source
FAQs on Types of Generators Explained: Principles and Applications
1. What is an electric generator and on what principle does it work?
An electric generator is a device that converts mechanical energy into electrical energy. It does not create energy but transforms it from one form to another, following the law of conservation of energy. The working principle behind most electric generators is electromagnetic induction (EMI). This principle states that when the magnetic flux linked with a conductor or coil changes, an electromotive force (and hence a current) is induced in the conductor.
2. What are the two fundamental types of electric generators based on the current they produce?
Based on the type of electrical output, generators are fundamentally classified into two main types as per the CBSE syllabus for 2025-26:
- AC (Alternating Current) Generator: This generator converts mechanical energy into electrical energy in the form of an alternating current, which periodically reverses its direction.
- DC (Direct Current) Generator: This generator converts mechanical energy into electrical energy in the form of a direct current, which flows in only one direction. This is achieved using a component called a commutator.
3. What are the common types of generators based on their application and fuel source?
Beyond the fundamental AC/DC classification, generators are also categorised by their use-case and the fuel they consume. Common types include:
- Portable Generators: Lightweight and used for temporary power needs.
- Inverter Generators: Quiet, fuel-efficient, and produce stable power, ideal for sensitive electronics.
- Standby Generators: A permanent backup system that automatically powers a home or building during an outage.
- Fuel-Based Generators: These include Gasoline, Diesel, Propane, and Natural Gas generators, each named for the fuel it uses and having different operational costs, emissions, and maintenance needs.
4. How is an AC generator different from a DC generator in construction and output?
The primary difference lies in their construction, which dictates their output. An AC generator uses slip rings, which allow the current to reverse its direction with each rotation of the coil, producing an alternating sine wave output. In contrast, a DC generator uses a split-ring commutator. This device reverses the connection to the external circuit every half rotation, ensuring the current in the external circuit always flows in the same direction, producing a direct current output.
5. Which type of generator is best suited for residential use during a power outage and why?
The best choice depends on the user's needs. A Standby Generator is often considered the best for whole-house backup because it starts automatically, can power an entire house, and often runs on natural gas for a continuous fuel supply. For more limited or temporary needs, a Portable Generator is a cost-effective choice for running essential appliances. An Inverter Generator is an excellent portable option if you need to power sensitive electronics like laptops and TVs, as it provides a more stable and clean electrical output.
6. Why does a generator not create energy, but only transform it?
A generator operates based on the law of conservation of energy. This fundamental law of physics states that energy cannot be created or destroyed, only changed from one form to another. In a generator, mechanical energy (from a rotating turbine, a diesel engine, etc.) is used to move a coil within a magnetic field. This input of mechanical work is then transformed into electrical energy through electromagnetic induction. The generator itself is just the medium for this energy conversion.
7. What are the main advantages and disadvantages of using a diesel generator compared to a gasoline generator?
Both diesel and gasoline generators have distinct pros and cons.
Diesel Generators:
- Advantages: They are more fuel-efficient, have a longer lifespan, and diesel fuel is less flammable than gasoline.
- Disadvantages: They are generally more expensive upfront, produce higher emissions, and can be heavier.
Gasoline Generators:
- Advantages: They are typically cheaper to buy and more portable.
- Disadvantages: Gasoline has a shorter shelf life, they have higher fuel consumption, and produce more emissions.
8. What types of generators are typically used in large-scale power plants?
Large-scale power plants, which supply electricity to the grid, primarily use massive three-phase AC generators, also known as alternators. These generators are driven by turbines that are powered by various sources, such as:
- Steam Turbines in thermal (coal, gas, nuclear) power plants.
- Water Turbines in hydroelectric power plants.
- Gas Turbines in natural gas power plants.
- Wind Turbines in wind farms.
These generators are designed for extremely high efficiency and continuous, stable power output to meet city-wide or regional electricity demands.
9. Why is the current produced in a generator called an 'induced' current?
The term 'induced' means to be produced without direct contact or physical connection. In a generator, the electrical current is not created by a battery or a direct chemical reaction. Instead, it is generated or 'induced' in the wire coil simply because the coil is moving through a magnetic field (or the magnetic field is changing around the coil). This phenomenon, where a changing magnetic field creates a current in a nearby conductor, is called electromagnetic induction, and the resulting current is therefore known as an induced current.
