Overview
IEC 62054-21:2004 - Electricity metering (a.c.) - Tariff and load control - Part 21 - specifies particular requirements for the type test of newly manufactured indoor time switches with operation reserve. It covers devices used to control electrical loads, multi‑tariff registers and maximum‑demand devices in electricity metering systems. The standard applies to time switches that keep real time (and optionally date, leap years, daylight saving and synchronization), and that use analogue mechanical dials or electronic digital displays (synchronous or crystal‑controlled). IEC 62054-21 is intended to be used alongside IEC 62052-21; where overlap occurs, its requirements take precedence.
Key Topics and Requirements
- Scope and device types: Indoor time switches for tariff switching, load control, multi‑tariff and maximum‑demand equipment; integrated functionality in meters is covered where applicable.
- Type tests: Defines type test requirements for newly manufactured units; includes mechanical, climatic and electrical type tests.
- Mechanical & display requirements:
- Analogue dials: readable to the nearest minute, direction of rotation marked, indelible markings.
- Digital displays: legible, each displayed value identifiable (codes/indicators), display time of at least 6 s.
- Time setting & programming:
- Mechanical dials: day‑dial setting accuracy better than ±7.5 min, programming resolution ≤15 min (week and year dials have coarser resolutions).
- Digital devices: time/date settable with 5 s accuracy; programming resolution down to 1 minute.
- Time‑keeping & operation reserve:
- Requirements for operation reserve (back‑up) and time‑keeping accuracy (e.g., synchronous devices specified to maintain accuracy under normal conditions).
- On supply restoration outputs must assume the program‑determined position quickly (outputs to position within 5 s; program execution to resume within 6 h after prolonged interruption unless otherwise agreed).
- Electrical, EMC and interference tests: Supply voltage/frequency ranges, immunity to voltage dips/interruptions, electromagnetic compatibility and radio‑interference suppression tests are specified or referenced.
- Tests & annex: Test conditions, type‑test procedures and an informative Annex A with example acceptance tests are included.
Applications & Who Uses It
- Utilities and grid operators for tariff switching, peak‑load shedding and demand management in Smart Grid deployments.
- Electricity meter and time‑switch manufacturers for product design and type compliance.
- Test laboratories and certification bodies performing type testing and conformity assessment.
- Meter integrators, DER aggregators and building energy managers implementing scheduled controls tied to tariffs or load profiles.
Related Standards
- IEC 62052-21 (general requirements, tests and conditions for tariff/load control equipment) - use in conjunction.
- IEC 62054-11 (electronic ripple control receivers).
- IEC 62059 series (dependability and reliability of metering equipment).
- Replaces IEC 61038 (particular requirements for time switches).
Keywords: IEC 62054-21, time switches, electricity metering, tariff switching, load control, operation reserve, time‑keeping accuracy, Smart Grid, type test, EMC.
