An electricity meter is an instrument used to calculate electricity consumption. Its unit is "KW·h" (kilowatt-hour), which is the "degree" we often refer to as how many kilowatt-hours of electricity are consumed. A normal power of 1kW electrical device consumes 1KW·h (kilowatt-hour) of electricity when working for 1 hour, that is, it uses 1 kilowatt-hour of electricity.

Common types of energy meters include single-phase energy meters, three-phase four-wire active energy meters, three-phase three-wire active energy meters and reactive energy meters. At present, there are two types of electricity meters used in the market: mechanical and electronic.

Mechanical energy meters have advantages such as high overload capacity and low cost, but they are easily affected by factors such as temperature, voltage and frequency. Electronic energy meters process the collected electrical pulse signals by using integrated circuits and have the advantages of high precision, good linearity and wide operating voltage range.

Therefore, electronic energy meters are gradually replacing mechanical ones. In the future, when choosing an energy meter, electronic energy meters should be given priority.