Accuracy rating of the meter

The rating of the meter is used to indicate the accuracy of the meter.

China's prescribed electricity meter is divided into seven grades: 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, 5.0.

The smaller the rating, the higher the accuracy of the meter. Usually the level of the meter used is marked on the dial of the meter.

The level of the meter can reflect the accuracy of the meter because the level of the meter is determined by the measurement error of the meter.

When measuring with an electric meter, the difference ΔX between the indicated value X of the electric meter and the measured actual value X0 is called the absolute error of the electric meter measurement.

The absolute error value is the ratio of the electric meter to the process Xn. The value expressed as a percentage is called the reference error En of the electric meter, that is, En=(ΔX/Xn)×100%.

When measuring with an electric meter, the maximum reference error Enm obtained will be obtained. Remove the % number and set it as the rating of the meter.

If the result is between two specified rating values, then the rating of the meter is set to a low accuracy level.

For example, the maximum reference error value measured by a meter is 0.7%, and the level of the meter is set to 1.0, but not to 0.5.

When measuring, knowing the level of the meter used and the range of the meter, you can calculate the maximum absolute error measured to estimate the accuracy of the measurement.

Common active energy meters have three accuracy levels of 0.5, 1.0, and 2.0. The allowable error of the 0.5-level electric energy meter is within ±0.5%; the allowable error of the 1.0-level electric energy meter is within ±1%; the allowable error of the 2.0-level electric energy meter is within ±2%.

The general resident customer is a Class V energy metering device, and the accuracy level of the active energy meter used is not less than 2.0; and the large power customers with a monthly average power consumption of 1 million kW·h and above are Class I energy metering devices. The active energy meter used has an accuracy level of not less than 0.5.