Electricity metering equipment - Particular requirements - Part 21: Static meters for AC active energy (classes 0,5, 1 and 2)

IEC 62053-21:2020 applies only to static watt-hour meters of accuracy classes 0,5, 1 and 2 for the measurement of alternating current electrical active energy in 50 Hz or 60 Hz networks and it applies to their type tests only. This document applies to electricity metering equipment designed to: • measure and control electrical energy on electrical networks (mains) with voltage up to 1 000 V AC; • have all functional elements, including add-on modules, enclosed in, or forming a single meter case with exception of indicating displays; • operate with integrated or detached indicating displays, or without an indicating display; • be installed in a specified matching socket or rack; • optionally, provide additional functions other than those for measurement of electrical energy. Meters designed for operation with low power instrument transformers (LPITs as defined in the IEC 61869 series) may be tested for compliance with this document only if such meters and their LPITs are tested together and meet the requirements for directly connected meters. This document does not apply to: • meters for which the voltage line-to-neutral derived from nominal voltages exceeds 1 000 V AC; • meters intended for connection with low power instrument transformers (LPITs as defined in the IEC 61869 series) when tested without such transformers; • metering systems comprising multiple devices (except LPITs) physically remote from one another;