The single-phase watt-hour meter, commonly used in 220V residential circuits, measures household electricity consumption. Its core components include voltage and current coils, a rotating disc, a rotating shaft, a braking magnet, gear mechanisms, and a display unit. Known for low energy consumption and high reliability, this meter helps users understand energy usage patterns and calculate electricity costs efficiently. 

The following section explains the working principle of single-phase watt-hour meters.

I. How does a single-phase watt-hour meter work?

When connected to a circuit under measurement, the voltage coil generates alternating magnetic flux (φU) that passes through the aluminum disc via the return pole. Simultaneously, the current coil produces alternating flux (φI) which traverses the aluminum disc in opposite directions through the U-shaped core. The interaction of these two phase-shifted magnetic fields induces eddy currents in the disc, creating rotational torque proportional to the circuit's power consumption.  

The magnetic return plate, constructed from steel sheet, extends into the lower section of the aluminum disc, forming a closed magnetic circuit with the voltage coil core. When AC fluxes from the voltage and current coils pass through different sections of the aluminum disc, they induce localized eddy currents. The interaction between these fluxes and eddy currents generates rotational torque, driving the aluminum disc's rotation.

Selecting appropriate meter specifications is crucial for measurement accuracy and device protection. An oversized meter yields inaccurate readings under low loads, while an undersized unit risks overload damage. For standard 220V single-phase applications: 

• 1A meter range: 11W (min) to 440W (max) 

Matching load requirements with correct specifications guarantees both measurement precision and operational safety.

Standard 220V single-phase meters deliver defined load parameters: 1A units support up to 440W, 2.5A models cover 27.5W-1100W, and 5A versions serve 55W-2200W applications, ensuring accurate measurement for residential to light commercial use.

II. What should be paid attention to when installing single-phase electricity meters

As single-phase watt-hour meters continue to play a critical role in modern residential energy measurement, industry experts highlight several key installation guidelines to ensure accuracy, safety, and reliable long-term performance.

1. Following meter installation, technicians must verify the integrity of bilateral sealing mechanisms, activate the main circuit disconnecting switch, and perform illumination testing to confirm proper meter functionality. This procedural step ensures both regulatory compliance and operational readiness.

2. Engineers emphasize that meters should be installed in dry, stable locations away from sunlight, moisture, and corrosive gases. Proper vertical alignment remains essential, as deviations may lead to measurement errors. The meter should also be positioned at heights suitable for convenient reading while strictly maintaining safety requirements.

3. Electrical specialists further advise that cables be connected per wiring diagrams and that all terminal screws and retention hooks be securely fastened to prevent operational faults or potential hazards during long-term use.

4. Electric meter wiring tips:

4.1. During installation, the current coils must be wired in series with the phase line, while voltage coils connect in parallel across the electrical equipment, following schematic specifications. This configuration ensures that current and voltage values are accurately captured during operation.

4.2. Industry standards also require generator terminals of both current and voltage coils to connect to the same power supply polarity to ensure proper meter operation and prevent reverse torque phenomena.

5. After the meter installation is complete, technicians must close the isolation switch and activate electrical equipment to confirm the aluminum disc rotates from left to right. A slight disc movement when the equipment is switched off is considered acceptable, provided it does not exceed one full rotation—an important indicator of meter stability and calibration integrity.