A phase meter is a diagnostic tool that is used to detect electrical waves being transmitted through a power source, and it measures the overall delivery of electricity. These devices run continuously, measuring both voltage and the ensuing current being supplied to any electrical circuit to provide an accurate reading of overall power consumption. On standard models, an aluminum dial is connected to a readout screen to display the amount of power used at any given time by monitoring the number of revolutions that the disk makes per hour. The resulting numbers on a phase energy meter are displayed either in kilowatt hours (kWh) or megajoules (MJ) to determine the total usage for that structure. Properties equipped with a phase meter are billed at certain intervals for the total usage of kWh or MJ, depending on their geographical location, and a history of the average usage is recorded by the electricity provider.
Globally, almost every residential and commercial building that is equipped to receive power from a centralized grid is equipped with a phase meter to measure the current that passes into it during any given period of time. This normally is conducted for billing and statistical purposes, but a phase meter also safeguards an electrical circuit from unintentional overloads that could damage any electronic devices connected to that grid. There also are various safeguards in place to prevent the tampering of a phase rotation meter by those who would benefit from showing a lower usage than the actual amount of power transferred.
The type of phase power meter installed varies by region. For example, prepaid meters are popular throughout Europe, but other countries rely on a monthly or semiannually billing process. There also are variations of electronic and mechanical phase meters that are used throughout the world that can serve a variety of functions, such as automatic usage reporting, outside interference or unusual draws of sudden power. A three phase meter is utilized to allow for a more evenly distributed, constant flow of power when heavy machinery or devices that require large amounts of power are used. Some companies choose to install smart meters that give more accurate real-time measurements of power usage and can automatically bill variable amounts depending on the time of day or the seasonal temperatures.