There are two types of systems available in electric circuit:

Single-phase and three-phase generators provide power differently. The most obvious evidence of this is seen in power delivery. Both types provide AC power, but a three-phase system produces three separate waves of power, delivered in sequence. This ensures a continuous uninterrupted flow of power that never drops to zero and makes three-phase generators more powerful than single-phase generators.

Single-phase generators deliver one constant wave of power however; the power level varies with the electrical current coming in. That means power levels can drop to zero during the cycle. This happens very quickly and is undetected by humans and rarely has an effect on whatever device is being powered. In fact, residential power is single phase and there’s never a problem powering devices in our homes. But for very large and demanding power applications, this dip can cause harm which is why three-phase systems exist.

The easiest way to visualize these power differences is to imagine a wave. One single wave (i.e. a single phase system) starts at zero, goes up to the peak, and goes back down to zero before the next wave starts. In a three-wave system, the three waves in sequence each individually look and act the same as the single wave, but since they arrive in sequence, their total power overlaps a bit providing more power than the single phase circuit, keeping that power always above zero, and distributing the total load over three phases/waves so there is less draw on one single wave.

It All Comes Down To Power Needs
If you’re questioning whether you need a single-phase or a three-phase generator, you need to think about your power needs and your budget. Single-phase systems are less complex and less costly. They are more common in residential or rural applications where the loads are relatively small. Unsurprisingly, 3-phase systems are more costly to install and maintain, but depending on your power needs, they may be a necessity.

3-phase systems are ideal for high-capacity settings which is why you usually only see them in industrial and commercial areas. Data centers, in particular, benefit from 3-phase backup generators due to the increased distribution capacity. 3-phase systems can power multiple racks whereas single-phase systems cannot.