Electric power is not all the same. What you need depends largely on your application. 

Whether you are a homeowner or a business owner, we'll help you understand the differences between single and three-phase electricity so you can be sure you're getting the perfect generator for your needs. 

 

You Need Different Power, Not More Power!

You may be wondering why your contractor is saying you can’t power that electric boiler or 2-cycle air compressor with a single-phase generator. If you're running a business, it may be a given if you're already running three-phase power. But what if you have the option to choose? What if you have an electric vehicle that you want to fast-charge?

At a certain point, single-phase motors can only produce so much electricity before they become so inefficient or unstable (read overheating wires) that multi-phase power is necessary to produce and carry the electrical load. If you're using any machinery, equipment, or appliance that operates on three-phase power - you cannot use a regular generator as a backup. Conversely, if you only have single-phase equipment, with no plans to change, you can use a single-phase generator, even though it might not be as efficient at higher kilowatt ranges. 

So what's the difference between single and three-phase generators? Let's take a look at how electrical phases work to find out. 

 

AC/DC

It may not sound as exciting as the band; however, you may recall from school that electricity in a circuit is made up of flowing electrons. Negatively-charged electrons flow toward positively-charged atoms (electron flow), and it's this movement of electrons that creates electricity. 

There are two types of electrical current, direct current (DC) and alternating current (AC). Just as the names indicate, direct current produces a continuous flow of electricity, while alternating produces fluctuations consisting of peaks and valleys at a rate or frequency. Sources of constant DC power include batteries and solar panels, while AC power comes from generators and power plants.

Whether your supply of AC power originates from nuclear, wind, or water (like from the Hoover Dam), those energy sources drive alternators inside turbines that produce alternating current along the grid. The power is then sent to power stations and conditioned before it reaches your meter. This "conditioning" refers to keeping the electrical flow very consistent in amplitude (amount) and rate (frequency). 

The standard frequency in North America is 60 hertz. And, you'll quickly notice any power fluctuations. Too much power can be hazardous and destroy equipment, while too little power can cause outages like blackouts and brownouts. The same can happen when the frequency fluctuates too much as well. 

 

We call these variations dirty power, and when referring to a generator, it's called total harmonic distortion (THD). Luckily, standby generators condition the electricity so that THD isn't an issue like it can be with some open-frame portable generators.   

  

Single-Phase Power

In single-phase electrical applications, power is delivered over one set of wires, typically hot (negative), neutral (positive), and ground. When viewed on an oscilloscope, a single wave pattern can be seen. 

You can think of this single circuitry as throwing a ball up in the air and catching it with one hand. If the ball isn't too heavy, like a tennis ball, and not being thrown too quickly, the task isn't that difficult. However, imagine you are now trying to throw a bowling ball faster and higher in the air. Your arm will soon get tired, and the chance of dropping the ball dramatically increases. The same thing happens with electrical circuits when they are overloaded. 

Three-Phase Power

By delivering electricity over multiple circuits, the power can be more effectively managed and timed using multi-phases. 

With three-phase power, the alternating current is not only evenly spaced out but can handle heavier loads more efficiently. Returning to the juggling analogy, three-phase power is like juggling three balls. Instead of trying to juggle a nine-pound bowling ball with one hand, spread that weight across a few three-pound balls and three hands! Not only are you juggling one pound per hand, but there is a greater effect where you cannot tell when a ball is up or down... that's what three-phase power gives you. The ability to run more power more efficiently, reliably, and with greater ease and somewhat more dependability in fluctuations.

A common question we get is whether there's a safety difference between single and three-phase power. And there is certainly a difference in the number of amps (weight) between the two types. For the same wattage, three-phase power will carry the load using fewer amps than single-phase power, making it theoretically safer, all things being equal.  

 

Single-Phase vs. Three-Phase Generators

With three-phase generators, you will notice that they operate at lower engine RPMs than their single-phase brethren, sometimes half the speed or more. The slower speeds mean less noise, longer engine life, and possibly less overall maintenance over the generator's lifespan.

Because of the reduced speed, three-phase generators are also more economical. Comparing the fuel consumption ratings, you will notice that three-phase generators use far less fuel than single-phase generators. 

 

Are 3-Phase Generators Better?

Again, it depends on your specific application and load requirements, not just for now but also for the future. Sure, single-phase generators are less expensive upfront, but if you have multiphase equipment or have high power demands, you will sacrifice efficiency and costs over the longterm. 

If you’re still not clear about which phase electric generator you need, our product experts are happy to help. Please contact us with your questions.

 NEXT: How to Pick the Perfect Commercial Generator