What is the measurement principle of ETL energy meter to calculate energy consumption?

The measurement principle of an ETL (Electronic Totalizing) energy meter typically involves using current transformers (CTs) and voltage transformers (VTs) to sample and measure electrical parameters. Here’s a simplified outline of the measurement principle:

Voltage Measurement:
The meter uses a voltage transformer (VT) to step down the voltage of the electrical system to a level suitable for measurement (typically 110V or 120V for standard meters).
This reduced voltage is then fed into the meter’s internal circuitry for processing.

Current Measurement:
Current transformers (CTs) are used to step down the current flowing through the electrical circuit to a manageable level for measurement.
The secondary winding of the CT provides a proportional current to the primary circuit’s current, which is then fed into the meter.

Power Calculation:
The meter calculates the instantaneous power (P) by multiplying the sampled voltage (V) and current (I) values: P=V×I.
This calculation gives the real power (active power) consumed by the electrical load at any given moment.

Energy Accumulation:
Over time, the meter integrates the instantaneous power readings to accumulate energy consumption in kilowatt-hours (kWh).
The meter typically samples these values at regular intervals (e.g., every few seconds or minutes) to provide accurate cumulative energy readings.

Accuracy and Calibration:
To ensure accuracy, ETL energy meters are calibrated based on the standards and specifications relevant to their intended use (e.g., IEC or ANSI standards).
Calibration involves verifying the meter’s output against known loads and adjusting it if necessary to maintain accuracy over its operational life.

The measurement principle relies on precise sampling of voltage and current, coupled with accurate calculations of power and energy consumption over time. This enables ETL energy meters to provide reliable data for monitoring and managing electrical usage in various applications.