What is an energy meter and what does it measure?

Energy meter definition and measurement scope:

• Energy meter (electricity meter) : Device that continuously measures active electrical energy consumed in a circuit. Displays cumulative kilowatt-hours (kWh) consumed since meter installation or last reset.
• Measurement calculation : Energy = power × time (kWh = kW × hours). Example: 10 kW load running 8 hours = 80 kWh energy consumed. Meter internally integrates instantaneous power (watts) continuously, outputting cumulative energy.
• Parameters measured : - Voltage (per phase, RMS AC). - Current (per phase, RMS AC via current transformers). - Power factor (cos φ; ratio active/apparent power). - Active energy (kWh; positive direction, "energy imported from grid"). - Reactive energy (kVAh; inductive/capacitive power oscillation). - Active power instantaneous (kW current power demand). - Frequency (50 Hz or 60 Hz verification).
• Metering periods : Standard meters record kWh at fixed intervals (15-minute, hourly, daily). Example: "04:00–05:00 consumption: 15 kWh" allows time-of-use tariff billing (peak vs off-peak rates).
• Accuracy class : Per IEC 62053-22, typical meters Class 0.5 (±0.5% error over 20%–120% rated current) or Class 1 (±1% error). MID-certified meters Class 0.5S/0.2S for official billing.
• Bidirectional metering : Modern meters can measure both directions simultaneously (import from grid, export to grid). Critical for solar PV installations or local generation. Bi-directional energy = net metering capability.
• Interface communication : Meters output energy data via Modbus RS485, Modbus TCP, M-Bus, pulse contact, or direct display (LED digits). Building management systems (BMS) query meter for real-time consumption.
• Energy tariff applications : - Single tariff: fixed rate all hours (residential, small commercial). - Dual tariff: peak rate (07:00–23:00) and off-peak rate (23:00–07:00). Meter sums energy separately per period. - Multi-tariff: up to 4 time-of-use periods. Industrial customers may have summer/winter rate variations.

Socomec energy meters (DIRIS A60, POWERSYS) certified per IEC 62053-22 (non-billing) and EU Directive 2014/32/EU (MID certified for billing). Modular hardware: same electronics support single-phase 230V and three-phase 400V installations. Data logging up to 12 months. Integration ISO 50001 energy management systems. Contact optim-elec.com.