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Single Phase Vs. Three Phase, what is the difference?

This is a question that comes up regularly when we speak to our customers. While three phase power is not required to operate any of our ground power units (GPUs), we will take a bird’s eye view of the differences between these power delivery systems in this article.

 What is single phase electricity?

Single phase power consists of a total of three wires. Two of these wires carry the load and are known as “hot” wires, and the third is a “ground” or “neutral” wire. In general, AC electricity is shaped like a sinusoidal wave when viewed on an oscilloscope. Single phase power appears as a single wave with voltage peaks at both the top and the bottom of the wave.

What is three phase electricity?

Three phase power can consists of a total of three or four wires. There is no “neutral” in three-wire setups, which means that all the wires are “hot”. In a four-wire setup, three wires carry the load (Hot) and one wire acts as the “ground” or “neutral” wire. When viewed on an oscilloscope, three separate waves appear. There are more peaks and valleys than what is seen on a single-phase wave, which results in the voltage being very steady and able to handle much higher loads.

A simple way to visualize the difference between single-phase and three-phase electricity.

Picture a canoe with a single paddler in it. The canoe will only move forward while the paddler moves his oar through the water. When the oar is out of the water there is no power moving the canoe. Now picture the same canoe, but with three paddlers in it. If their strokes are timed so they are never all out of the water at the same time, the boat will have more power and more consistent propulsion through the water.