14
6.2 Functional circuit diagram
Figure 7: Functional circuit diagram
6.3 Tariff switching clock
The tariff switching clock works on the basis of a Real Time Clock (RTC) and can be set
via the D0-interface. The accuracy is within
5 ppm. The tariff switching clock gives the
time when the tariff switching should take place. Tariff switching can be parameterised,
one tariff is always active. External tariff control is possible; thereby the internal tariff
control is automatically deactivated. The ITZ has separate daily switching clocks for
weekdays and holidays.
The following day types are supported:
a) Monday - Friday
b) Saturday
c) Sunday
d) Holidays
Setting the date and time
The date and time can be set with the software EMH-COM or EMH-COMBI-MASTER
2000 either via the optical- or the electrical interface. In Germany, according to the PTB
requirements, the latter may only be carried out once after ending the parameter status
or after voltage return.
Synchronisation of the Real Time Clock
takes place via:
a) the internal quartz or
b) the synchronisation input.
Buffering of the Real Time Clock
takes place
a) with battery or
b) with capacitor.
The battery guarantees a running reserve of > 10 years, the capacitor of > 7 days.
With a completely discharged capacitor the charging time is approx. 20 minutes after
applying the phase voltage (90% voltage). If the running reserve is exhausted then in the
display the relevant symbol is displayed (see page 21). After voltage return the Real
Time Clock is set to the time of the network power failure. Furthermore, the energy is
registered in a fixed register (depending on the configuration 1.8.0, 1.8.1, 1.8.2, 1.8.3 or
1.8.4).
