AS 62054.21:2018 pdf download.Electricity metering (AC)- Tariff and load control Part 21: Particular requirements for time switches (IEC 62054-21:2017 (ED.1.1), MOD).
7.1.5 Long interruptions of supply voltage
7.1.5.1 Requirements
During an interruption of the supply voltage not exceeding the operation reserve, the time switch shall keep the time within the prescribed accuracy (see 7.5.2). The output elements shall take up the position determined by the time switch programme within 5 s after the restoration of the nominal supply voltage.
If the length of the interruption of the supply voltage exceeds the operation reserve, the time may need to be re-adjusted. The time switch shall begin to execute the time switch programme within 6 h following the restoration of the supply. However, the user and the supplier may agree that, after a prolonged interruption of the supply voltage, the time switch does not restart, the outputs take up a pre-determined position and the time switch displays a special flag.
7.1.5.2 Test of effect of a long interruption of the supply voltage
For testing the time-keeping accuracy on operation reserve, see 7.5.2.3. The test of the behaviour of the output elements consists of verifying that, after Interrupting the supply voltage for an agreed length of time and when the supply is restored to the time switch, the output elements take up the position as determined by the time-switch programme, according to the indicated time. This test shall be carried out for all possible positions of the output element(s).
The restoration of the supply voltage shall be made with the switching device free from bounce.
7.5.1 Time setting and programming
7.5.1.1 Time switches with mechanical analogue dials
On a day dial, it shall be possible to set the time with an accuracy better than ±7,5 min.It shall be possible to programme the switching operations with a resolution of 15 min or smaller and it shall be possible to programme a minimum of two successive switching operations at least within 60 min. On a week dial, it shall be possible to set the day of the week and the time with an accuracy better than 1 h. It shall be possible to programme the switching operations with a resolution of 2h or smaller and it shall be possible to programme a minimum of 2 successive switching operations at least within 8 h. On a year dial, it shall be possible to set the date and time with an accuracy better than 2 days. It shall be possible to programme the switching operations with a resolution of 4 days or smaller and it shall be possible to programme a minimum of 2 successive switching operations at least within 16 days.
7.5.1.2 Time switches with digital displays
It shall be possible to set the date and time (day, month, year, hours and minutes) with an accuracy of 5 s. The setting of the time shall reset the seconds to zero. If setting of the seconds is also available, then the setting of the time shall not reset the seconds to zero, but to the intended value.
NOTE In this case, it is preferable to display also the seconds. If a daylight saving function is available, the time switch shall display the official time
according to the regulations. It shall be possible to set the switching operations with a resolution of 1 minute, 1 hour, 1 day, 1 month and 1 year.
7.5.2 Time-keeping accuracy
7.5.2.1 Requirements for synchronous time switches
Synchronous time switches shall have a time-keeping accuracy under normal operating conditions better than +5 s/30 days assuming that the supply frequency keeps its average on the nominal value.
On operation reserve, at reference temperature, the time-keeping accuracy shall be better than士120 s/day, if operation reserve is provided by a spring and better than 士1 s/day if operation reserve is provided by a supercapacitor, rechargeable battery or primary cell.
7.5.2.2 Requirements for crystal controlled time switches
At reference voltage and reference temperature, crystal-controlled time switches shall have a time-keeping accuracy better than ±0,5 s/day. The variation of the time-keeping accuracy with the temperature shall be less than (±0,15 s/°C/24 h).AS 62054.21 pdf download.