Three-Phase Electricity Meter: Working Principle and Key Differences with Single-Phase Electricity Meter
Single-Phase Watt-Hour Meter
A single-phase watt-hour meter is designed for active energy metering. It is accurate, modular, and compact (only 18mm wide), making it easy to install in terminal distribution boxes. It features DIN-rail mounting with bottom wiring, perfectly compatible with miniature circuit breakers. Its intuitive mechanical display is easy to read and helps prevent data loss during unexpected power outages. This meter operates without the need for an external power supply and functions across a wide temperature range. It is ideal for commercial buildings and public infrastructure, enabling accurate measurement and statistics of power consumption across different areas or loads. It is also suitable for industrial buildings, providing energy consumption statistics for various production lines or loads and supporting internal accounting.
How a Three-Phase Watt-Hour Meter Works
A three-phase watt-hour meter measures the energy output (or consumption by a load) in a three-phase AC circuit. Its working principle is similar to that of a single-phase meter, with the main difference being the use of multiple sets of driving components and aluminum disks on the rotating shaft to measure three-phase electrical energy.
Three-phase watt-hour meters are classified as either active or reactive, depending on the type of electrical energy being measured. They are typically used in a three-phase four-wire system. Below are some characteristics of the three-phase active watt-hour meter:
Key Differences Between Three-Phase and Single-Phase Meters
A three-phase four-wire active watt-hour meter consists of three driving elements and three aluminum discs mounted on the same rotating shaft. Its reading directly reflects the total power consumed by the three-phase system. In some models, three sets of driving components act on a single aluminum plate. This design offers advantages like a smaller size, lighter weight, and reduced friction torque, which improves sensitivity and extends the meter’s lifespan. However, due to the interaction of 50 electromagnetic elements on the same disk, there can be increased interference from magnetic flux and eddy currents. Compensation measures, such as increasing the distance between electromagnetic elements and enlarging the diameter of the turntable, are required to mitigate these effects.
The three-phase three-wire active watt-hour meter uses a design where two sets of driving components act on either two aluminum disks or one disk mounted on the same shaft. The reading process remains the same. For more details on the structure and working principles of three-phase reactive watt-hour meters, readers can refer to related technical books.