UNE-EN 62052-21:2006 Electricity metering equipment (a.c.) - General requirements, tests and test conditions -- Part 21: Tariff and load control equipment (IEC 62052-21:2004)
2018UNE-EN 62052-21:2006/A1:2017/AC:2018-04 Electricity metering equipment (AC) - General requirements, tests and test conditions - Part 21: Tariff and load control equipment
2017UNE-EN 62052-21:2006/A1:2017 Electricity metering equipment (AC) - General requirements, tests and test conditions - Part 21: Tariff and load control equipment
2006UNE-EN 62052-21:2006 Electricity metering equipment (a.c.) - General requirements, tests and test conditions -- Part 21: Tariff and load control equipment (IEC 62052-21:2004)