The Characterstics of AC Power

Energy is at the core of twenty-first century life, and that energy mostly comes to us as electrical energy.

Mostly, when we use electricity, we get it from the mains grid.  We usually want our independent energy solution to provide us with electricity that has the same characteristics as the mains electricity, so that we can use appliances that are designed to run from the mains.

In Australia, that’s alternating current (AC), at 240 Volts and 50 Hertz. The two most important characteristics of an AC electricity supply are its voltage and frequency. Some appliances won’t work well if the voltage or frequency is not accurately controlled, and some appliances will be damaged if these characteristics are too far from their correct values.

For instance, the speed of an electric motor is directly related to the frequency of its electricity supply, so if the frequency is wrong the motor will turn at the wrong speed, and may not perform its task properly.  If the voltage is too low the motor may not be able to start, and will over-heat and fail.

Another important characteristic of an AC electricity supply is the smoothness with which the alternating current swings back and forth; this is called the waveform. Some appliances, particularly electronic appliances such as DVD players and computers, can be damaged by a poor waveform. The best waveform is called a sine wave, which looks like this: These characteristics of the AC electricity supply partly define the quality of an independent energy solution, and must be carefully considered when choosing one.