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How Do Generators Work?

A collage of how generator works.

An electric generator converts rotational mechanical energy into electric current. Steam turbines and gas turbines are all sources of mechanical energy.

Let’s start by dissecting the generator to understand how a generator works. Next, we will briefly discuss the components.

Past and Present

An antique generator in a mill.

Early generators used permanent magnets to convert kinetic energy to mechanical energy. They produce almost all the electricity consumed at the same time.

The generator today uses an electromagnet and not permanent magnets. An electromagnet, a magnet that is produced by electricity in a coil of wire, is an electric magnet.

This generator is different from one that uses permanent magnets. It is made up of several insulated coils which are wired together to form a stationary cylinder (the stator). The rotor is the rotating electromagnet mounted in this cylinder.

The electromagnet rotates and induces small electric currents in each section. Each section of the stator is a separate small electrical conductor.

Each section creates a small current which combines to create a large current. This is the electricity that flows through the power lines that connect generators and consumers.


Man hands holding an alternator.

The alternator produces electricity. The machine is called a generator because it produces electricity, not because it has a generator. An alternator is called an alternator, while a direct current generator should be called a dynamo.

Modern synchronous generators are powered by rotating field alternators. Armature winds are stationary and provide power without using brushes. Slip rings and brushes provide DC excitation power to the rotating magnetic field windings, so that the electrically generated magnetic field rotates.

Generator vs Alternator: What’s the Difference?

Electric generator on the street.

The speed of a rotating magnetic field is equal to the speed of a motor. It determines the frequency and voltage of alternating current. The regulator regulates voltage and amperage by controlling the current of the DC field windings.

The generator converts engine power into electrical energy. The voltage and amperage generated by a synchronous generator can be precisely controlled. It cannot keep the frequency constant when there are varying loads.

This is reflected in the slight drop in engine speed that occurs when a load has been applied to the generator.

The alternating frequency depends on two factors: the number of poles in an alternator and the speed at which the alternator spins (RPM). To produce 60 Hz, a bipolar generator must spin at 3600 rpm. To produce 60 Hz, a four-pole generator must spin at 1800 rpm.

Gasoline engines are starved at 1800 rpm. They can only produce maximum power at 4000 rpm. Bipolar alternators are used to maintain the motor in the power band generators.

The regulator regulates the frequency at 60 Hz by controlling the motor speed at 3600 rpm with a stepper motor.

Voltage Regulator

The voltage regulator controls the current in the DC field windings. It measures the output voltage and then compares it to a reference voltage. To maintain the output voltage at the nominal value, the circuit adjusts the excitation potential of the magnetic field windings.

Cooling and Exhaust Systems

Generator motor cooling system

Because synchronous generators produce a lot of heat, their cooling is crucial. Forced air circulation is used to cool the alternator and engine in portable generators. The fan that drives the motor draws in cool air from the atmosphere and blows it inside the motor.

All heated air is exhausted to the atmosphere. Open-frame generators dissipate heat more efficiently, but fan, motor, and generator noises are much louder. Noise canceling is not available and may make noise irritating to others.

To make the noise bearable, keep the generator away from people.


Closeup of generator engine.

Generator engines are small stationary industrial engines. Four-stroke engines are the most common engines used in portable generators. Four-stroke engines produce more torque at 3,600 rpm than two-stroke engines and can accommodate clean air regulations.

The size of the engine is determined by the required power of the generator. They range from 50cc overhead valve (OHV) engines to 670cc 4-stroke twin-cylinder OHV engines.

For cooling, all engines use forced air from the fan attached to one end of the crankshaft. Most portable generators use the same air to cool the alternator, but some models have a second cooling fan.

Both large and small engines are equipped with transistorized magneto ignition systems which ensure that the engine runs smoothly and starts instantly. Small engines have a recoil start system, which requires you to pull the cord to start the engine.

To start the engine, some larger generators include an additional 12-volt electric starter. As a backup, the booster launcher can still be used.

Normally, oil is used to lubricate the engine. To meet emission regulations, all engines use unleaded gasoline with an octane rating of 86 or higher. These compression ratios can also be quite high.

Generator engine exhaust reduces noise levels as much as possible. To prevent bushfires, they also install a spark arrester screen in the exhausts.

Fuel System

Yellow fuel tank of a gas generator.

Fuel tanks are usually made of steel and placed on the engine and alternator. Even small engines can use a float type carburetor. That’s why we have to use the generator on flat ground.

The fuel shutoff is used to shut off the fuel supply to the carburetor from the tank. It can be used with a drain valve, which is fitted to some carburetors, to drain the fuel. If your carburetor doesn’t have a drain cock, close the fuel shut-off valve while you run the engine and let the carburetor dry out.

Most generators have a manual choke for cold starting. Most generators with remote start controls use an automated choke.


If you have a generator in your home or are trying to decide whether to buy one or not, it is important to know how it works. From this article, we hope that you have gathered enough information to make your purchase.

A generator is something that every home should have, in case of an emergency such as a natural disaster. You should consider getting one.