AC static watt-hour meters, class 1 and 2 - IS 13779
This standard specifies static watt-hour meters of accuracy classes 1 and 2 for measuring alternating-current electrical active energy at frequencies ranging from 45 Hz to 55 Hz for single-phase, three-phase, balanced, and unbalanced loads. It only applies to static watthour meters consisting of measuring element and register enclosed in a meter case. It is also applicable to the operation indicator and the test output. It also applies to meters with multirate tariffs and meters that measure energy in both directions.