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How does a generator work? And more Q&As

clock 10 minutes | 05 Oct 2021

a generator with the door open exposing internal parts

Here, we answer the most common questions we hear about generators to help you understand what they do, the parts they’re comprised of and how they work. At Essentra Components, we don’t produce generators, but we do design, manufacture and distribute many of the small essential components needed to build these vital machines.

You can learn more on how we help design engineers with their needs with our Quick Guide: Components for Your Industrial Generator.

Before you read on, a quick word about vocabulary. One person might wonder, “What is a generator?” Someone else might ask, “What is an electric generator?” These are one and the same. We use these interchangeably in these Q&As, as questions are asked of us using both terms.

What is a generator used for?

Power outages are common in areas of extreme weather, making generators a necessity. Generators provide reliable backup power to hospitals, businesses and homes. For businesses and people who work from home, generators prevent downtime. For hospitals everywhere, generators guarantee light and power to keep live-saving machines working. For people who rely on medical devices at home, such dialysis equipment, generators provide peace of mind, along with the power their devices need to keep working.

Generators can also provide a permanent means of power, such as on construction sites and oil and gas operations.

How does a generator produce electricity?

It doesn’t. While there are different types of generators, they all perform the same function: they convert mechanical energy into electrical energy. How generators work is relatively simple. They capture the power of motion and turn it into electrical energy. They do this by forcing electrons from the external source through an electrical circuit.

How are generators powered?

That depends on the external source, or mechanical energy, mentioned above and can vary. Think of hydraulic turbines at dams, for instance. In addition to water, common external sources also include steam, solar, wind, diesel, gas or natural gas (propane). How does an electric generator work? How does a gas generator work? A gas generator is an electric generator that uses gas as its external source.

How do generators use magnets to create electricity?

Place a conductor in a changing magnetic field and the electrons in the conductor move. This is a process called induction and answers the question, how does a generator create currents?

How generators work: step by step:

  1. When the electrons move, they become electric currents.
  2. In generators, a copper coil, wound onto a metal core, acts as the conductor and is rotated between the poles of a horseshoe-type magnet. This conductor coil, together with the core, is called the armature.
  3. The rotor connects to a shaft of the external source with rotating magnets. Alternatively, these coils of wire can also be rotated through magnetic fields.

What type of current does a generator produce?

Some convert the mechanical energy into an alternating current (AC), while others convert to a direct current (DC). The electrical current in an AC generator reverses direction periodically, while a DC generator flows in a single direction. An AC generator uses magnets to create electricity: the coil is fixed while the magnets move. With a DC generator, the coils rotate in a fixed magnetic field. How DC generators work are little different. They use the rotor to convert the current to AC voltage. How does an AC generator work? It uses what’s called a commutator to convert to DC voltage.

DC generators are typically used to power extremely large motors, such as railways. AC generators are ideal to power home appliances.

What magnets are used in generators?

They can either be permanent or electric, which are the two main types of magnets. Small generators typically use permanent magnets and don’t need an independent power supply. Electric magnets are iron or steel and wound with wire. The magnetic field is created when electricity passes through the wire. This in turn causes the metal to become magnetic.

What parts are found in an electric generator?

Gas- or diesel-powered generators are the most popular for industrial and home use. Generator parts are the same, however. For example, both channel electrical power through power cables, although if we’re talking about a portable machine, you can plug an appliance directly into the generator’s socket. For our purposes, our electric generator diagram depicts an industrial diesel unit. Where parts of a generator are placed can vary and often depends on the size of the generator. Regardless, a generator and its parts, such as gasoline generation parts and those of diesel, will be the same.

a generator showing each part or component

Generator components

Electric generator parts and functions include:

1. Engine

What is a generator engine? All generators have engines, no matter what their external source, be it diesel or hydrogen. It’s the engine that supplies energy to the generator. The more powerful the engine, the more electricity a generator can provide. The main components of a diesel engine – or more accurately, the parts of a generator engine –also include:

1.a Fuel system

In this case, diesel is the external source, or mechanical energy. A tank will hold your fuel, which in a large generator, permanently install, is typically a separate structure. The fuel tank for smaller, portable units is usually held within the generator. Pipes will take the fuel to the engine, similar to a fuel pump in a vehicle. A fuel filter will remove contaminants from reaching the engine, and a fuel injector pushes the fuel into the combustion chamber.

1.b Cooling and exhaust systems

Generators need cooling systems to regulate the heat and prevent overheating. Coolant fluid absorbs the heat and is then run through a heat exchanger, which sends the heat into the air or into another coolant fluid.

How much ventilation does a generator need? Exhaust gases should be channelled away from the engine and people, and are usually directed through pipes and vented into the external air. Follow the manufacturer’s guidelines regarding how much clear space is needed around the generator, which will vary by machine.

1.c Lubrication system

Generators are comprised of small, moving components. As such, they need lubricating with engine oil to enable smooth operation while protecting them from excessive wear and tear.

2. Alternator

The function of alternators in diesel engines – or any engine – is where the external source, in this case, diesel, converts into electricity. Moving and stationary parts create the magnetic field and movement of electrons. This answers another common question: What's the difference between an alternator and a generator?

The alternator is where the energy conversion takes place within a generator. The main components of an alternator and its critical parts include:

- Armature

This is the main part of an AC generator, and where voltage is generated. It consists of coils that carry the full load current in the generator.

- Field

Where the magnetic flux is created. In AC generators, the magnetic field changes as the coils rotate.

- Slip Rings

These are electric connections that conduct the current from the stationary part to the rotating part.

- Stator

The non-rotating electrical parts of a generator.

- Rotor

The rotating part of the generator. It produces a magnetic field in the generator. Depending on the generator, the rotating part can also be the armature or the magnetic field.

3. Voltage regulator

It’s critical that the generator regulates the voltage to produce a continual current for practical use. This is the job of the voltage regulator, which helps control the electricity voltage produced. If needed, it also converts the electricity from AC to DC. It’s usually located in either the generator’s main control box or the terminal box of the alternator. On small, portable generators, you’ll typically find it under the alternator’s rear cover.

How does a voltage regulator work on a generator? It automatically compares the voltage from the generator terminals to a stable reference. An error signal then adjusts the field current as needed to an exciter stator, which is part of the alternator. This, in turn, will either increase or decrease the voltage at the main stator terminals.

4. Battery charger

Just as your car relies on a battery to start, so does a generator. The battery can be charged by either the generator output itself or a separate charger.

5. Control panel

The generator is operated by the control panel, and covers everything from start and shut down to engine speed to AC power frequency.

6. Frame/housing

This is the assembly that contains the generator and holds it in one place. You have several options for this, from waterproof housing to an open structural frame, as show here. Another function of the frame or housing is to safely ground the generator’s electrical components.

Portable generator parts aren’t much different. These also have an engine, alternator, and fuel tank, but also outlets to plug appliances into and a starter, which can be a push button or pull cord, similar to a lawn mower.

How much voltage does a generator produce?

It’s important to note that a generator’s power is expressed as watts or kilowatts. Watts is the amount of power the generator can safely output in a given time, but let’s back up. Remember, electricity is the flow of electrons through a conductor. Amperes – commonly known as amps – is a measure of how many electrons are flowing. Voltage is simply pressure. It’s the force that moves electrons through the conductor. Voltage plus amperes produces the power that’s measured in watts.

But what determines output voltage? The speed that the conductor moves through the fixed magnetic field, coupled with that field’s strength. This speed is a result of the engine’s rotational speed. As the engine’s speed increases, so does the voltage generated. Common voltages on commercial generators range from 120 to 4160 volts.

What would cause a generator not to produce power?

Usually, this points to a loss of residual magnetism. This can happen through the generator’s lack of use. Over time the reserve of magnetism drains until it runs out. Residual magnetism can also be lost when a generator is powering a load and you turn it off. This causes the load to suck the last of the generator’s magnetism. Yet another cause for losing residual magnetism is leaving the generator on for too long while failing to plug it into anything.

To prevent loss of residual magnetism, use the generator from time to time, even if you don’t need backup power. Be sure that you’re not using any plugged-in loads when you turn it off and finally, keep the generator plugged into something unless you’re about to power it down.

Download free CADs and try before you buy

If you’re designing your own generator, download free CADs and request free samples, which are available for most of our solutions. It’s a great way to ensure you’ve chosen exactly what you need. If you’re not quite sure which product will work best for you, our experts are always happy to advise you. Whatever it is you need, you can depend on fast despatch.

Request your free samples or download free CADs now.

Questions?

Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.

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