The Ultimate Guide to a 3 Phase Generator

By now, almost everyone has come across a generator, whether at their residential apartment, a construction site, or the workplace. At best, you’ve at least seen generators online. Just as these machines appear efficient as they roar to give power, so are they. Not all generators are the same, however. They come in many different power outputs, portability, different constructions, and even different sizes. Knowing the types of generators available will help choose the right type of generator based on your budget and intended use.

3 phase generators are mostly used for industrial power supply in the event of a failed power supply. Without a doubt, industrial use implies that they produce high amounts of power, to provide sufficient energy for an industry to run even without the mainline electrical supply present. 3 phase generators also come in different fashions. Continue reading this article to know more about 3-Phase generators.

What is a 3-phase generator?

As the word suggests, 3-phase generators are a unique category of generators that produce 3 alternating currents which have a similar frequency. They are however out of phase in that they are placed 120 degrees apart on the stator. These are the main features of 3 phase generators:

• They have 3 coils placed 120degrees apart on a stator.

• Coils voltage and frequency are similar.

• When added together, these three coils give thrice as much power compared to single-phase generators.

These are the bottom-line features of 3-phase generators. They individually, however, have different specifications depending on the size, power output, and portability. The only thing we could perhaps say is similar in all is the higher amount of energy yielded in comparison to the same version of a single-phase generator.

How does a 3-phase generator work?

With the three different coils, a 3-phase generator can produce 3 distinct power waves in a sequence. This means that throughout its use, a 3-phase generator provides a continuous power flow. It concurrently means that the power will never subside to zero, a problem that happens a lot with single-phase generators. With the 3 coils, these generators are also able to take on large capacities of power making them the chosen type of industrial warehouses and other commercial facilities.

The science behind its structural composition hence it's working mechanism can be quite mind-joggling but it may come in handy when knowing what the subtle differences between one and another are. This will help you choose the best 3 phase generator to meet your needs.

Mechanism of a 3-phase generator:

They have an internal combustion system that burns fuel, which in most cases is either petrol or diesel. This system starts with a generator head that has valves, spark plugs and fuel injectors mounted on it. The valves control the amount of input and output, the fuel injectors bring in fuel and the spark is ignited to start combustion. The head also provides an outlet for the exhaust gas to escape.

This head is perhaps the most important part of the generator. It is therefore quite expensive and ranges from 6Kva, 12Kva, and above. The higher the Kva, the more expensive they are, yet the higher, the more suitable they are for the 3-phase generators. The combustion of fuel provides mechanical energy to drive a dynamo.

As with all generators, there is a dynamo that rotates to give electrical power. It converts rotation energy, which is mechanical energy into electrical energy through the use of fuel. The electrical energy is fed in three alternating currents that are balanced. The power load from these generators being balanced protects appliances and electrical devices from destruction by eliminating irregular voltage surges.

Difference between single-phase and three-phase generators.

Being able to recognize the differences between a 3 phase and single-phase generator will help in identifying the best possible solution for your power needs.

The most major difference is perhaps the reliability of power supply, whereby the 3-phase as previously mentioned can give a continuous supply, thanks to the 3 alternating currents that are consistently producing power. The single power wave makes it come short in terms of reliability.

Single-phase generators use either aluminum or copper for electrical conduction, and so do the 3-phase generators. The main difference in this case, however, is that 3 phase generators will generally use a lesser amount of copper and aluminum to give the same amount of energy.

Single-phase generators are generally less complex in construction which makes them cheaper.

Due to this, their application also differs. Single-phase generators are preferable when using household appliances and other devices, that amount to a total of 1000 watts of power or less. They are suitable for homes, small businesses, and compatible with any horsepower 5. On the other hand, the 3-phase generators are perfect for large commercial enterprises like the manufacturing and processing industries.

The 3-phase generator saves labor requirements through machinery use, hence returns the value of an investment. It is advisable for these kinds of businesses because of less labor treatment costs, security risks, and can run high power loads.

Furthermore, considering the nature of the environment, production parameters, high power equipment that have high power motors as well, a single-phase generator cannot meet the need of industries. This is why the choice of a 3-phase generator is convenient, to offer the right amount of power.

In terms of construction, at the feeding unit, the 3-phase generator has 3 power wires which are fed electricity in three different phases, hence the name. It makes the conditions for power supply optimal by 4 different wires which are the neutral, and three more known as R S T.

Finally, the three-phase generators are also capable of carrying power over longer distances in comparison to a single-phase.

Calculating the power from a three-phase generator.

Thanks to their efficiency, the popularity of the 3-phase generator continues to grow. To properly understand their working mechanism, calculating the amount of power that is given will come in handy. Though the formula and process may a bit complex, it will also benefit you in determining the accurate amount of energy given by a generator to avoid being misinformed.

The calculation formula for three-phase power systems

To calculate the amount of power transmitted first is the equation formula, also known as Ohms Law:

P= 1.73 x pf x I x V


Prefers to the power of the system (in Watts).

pf refers to the power factor

I refer to the current in a circuit (in amps)

V refers to the voltage (in volt)

Applying the Ohms law formula to calculate Power Output:

The pf should range between 0.85 and 1. This gives a P and V of kilowatts and kilovolts respectively.

When it comes to applying the formula, ensure that you convert all readings into the standard units of measurement.

The voltage is measured using a voltmeter, whereby you then record the line to line voltage.

Find out the power factor of your generator.

Finally, examine the generator's load capacity in amperage.

Apply the formula.

Consideration when purchasing a 3 Phase generator.

We’ve already seen that generally, 3-phase generators will differ. When purchasing one, here are some factors to think about:

1. Do you get a new or used one?

Even without getting into the integrals of the generator, the first question to ponder upon is whether to get a new or second-hand generator. If you’re looking for a backup power source for your industry, commercial business or even construction site, numerous second hand and new generators are at your disposal. New ones from trusted manufacturers are available all-over online retail sites like Amazon.

When buying second-hand generators, however, you have to take precautions so as not to fall in the hands of fraudsters. This is through market research to understand performance levels of the available options after which you should inspect whether it meets the standards. To save yourself all the trouble, you should look for a reputable repair and installation expert, one who possesses the tools required to assess the workability of the device. With this, you even have the leverage to return for consultations in case of any malfunctions.

2. How much does the generator cost?

Of course, you do not want to go broke over a device that you’ll use as a backup source of power, especially if blackouts are rare in your specific location. There are different sellers in the market, so do your research to find the best price, and ensure that the range makes sense to avoid counterfeit goods. A second option that is in good shape will also save quite a sensible amount of money hence should be considered.

3. Does the generator quality meet your requirements?

3-phase generators are of many kinds, sizes, colors, power outputs, and could either be portable or not. To make the best decision, ensure that you assess whether the specifications match your desired product.

4. Brand

A reputable brand will ensure that the generator you opt for is efficient, of high quality, and durable. Once a generator is bought, you trust the generator to be reliable whenever it is called upon to provide energy in critical times. Choosing the right manufacturer minimizes risk, and guarantees performance strength.

5. Hours of operation

The best option would be purchasing one that is labeled low-hour. This means that is can run efficiently since it has been operating in a reasonably low number of hours.

6. Warranty

Warranty is a form of insurance, and since a generator is quite the investment, it will only do you good to purchase one that has a legitimate warranty. This minimizes the risk of your investment in case of any malfunction. This is where the disadvantage of buying a second-hand device comes in. In case you experience challenges, you have no claim over the warranty.

7. Voltage

There are 120V, 240V, 480V, and other types of 3-phase generators. Most industries use 480V since it has numerous application possibilities. It also accommodates the use of large loads for machinery. The 120V/240V is also versatile in that it could provide 120V and 240V options as well, and is known as the wild or high leg delta. The only problem with the former is that not being cognizant of the difference in voltages may cause problems. It is also portable, making it quite the catch.

8. Switching mode.

3- Phase generators could either have an automated or manual switching mode. Depending on preference, you may choose your desired mode.

9. Mobility

There are standby and portable types of generators, with the latter being the better option if you have more than one industry, and are looking to buy one generator to serve other locations too.

10. Fuel type

They could either use petrol/gasoline or diesel. While the diesel-driven tend to be more expensive, they give value for your money. This is because they give fuel economy in the long run. Besides this, they also run for longer hours than petrol-driven engines.

11. Engine Type.

If anything, this should be amongst the first considerations. Check the engine class, and gensets. In this case, the diesel gensets are preferred to gasoline. This is because they effectively turn mechanical into electrical energy with diesel. Even with everyday use, they are sturdy and will last long without wear and tear. In intensive workloads like the one in industries, they are perfect. When the power supply is low, a good engine will automatically rise to the task. Remember, the better your engine, the more efficient the generator is. It is the essence of power production.

Some Common Types of 3 phase Generators

480-volt 3-phase portable generator:

It is a very powerful kind which makes it effective for industrial plants with high power requirement machinery. It will also produce about 2 to 2.3 times the energy a regular 208V and 240V generator will give and has very low energy requirements. Finally, it uses less current requiring less wiring and construction implements which makes it very compact. This makes it quite easy to carry around from one site to another.

208v 3 phase portable generator:

They operate on sites without a battery requirement therefore suitable to contractors and projects with a high voltage consumption and out of reach from the main power lines. Not that their portability will, however, depend on the manufacturer, with the options of 2 or 4 wheels mounted on a framework. They have a built-in voltmeter and automatically shut down when oil levels are near depletion.

There are many other types, but these two stand out in terms of efficiency in use. You should also know when to alter the 3-phase generator to your preferred voltage, which is where the calculation comes in. Manufacturers will also have manual guides that will come in handy when calculating your power requirement for the home or business.

What are the main advantages of the three-phase generator?

  • They are smaller and lighter than single-phase generators.
  • More efficient in power supply hence more popular globally.
  • Total instantaneous power is also constant meaning it does not suffer variations in time.
  • They have fewer vibrations thanks to the constant torque
  • Higher power thanks to the windings and 3 coils.
  • They are very reliable in power production since they will never have zero power.
  • They also do not require other devices since they are powered by 3 phases.


In a nutshell, the 3-phase generators should always be the go-to when looking for a large power supply, like industrial use. This is also the case when looking for continuity in power supply and when you want a guarantee that there can never be a power supply failure as long as the generator is in good condition. If you want a device for high power equipment, opt for none other than the three-phase generators which will give you top-notch performance and efficiency!

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