ABB 2CSM258763R0621 standard digital time switches with 1CO contact, 6 years power reserve, 2 modules. The D1 time switch allows you to override the normal weekly program for one or more periods of the year or even through different years. It is equipped with large capacity internal batteries so they are able to function during a blackout and an EEPROM permanent data store, to ensure that the scheduled program is followed and the date and hour settings are maintained even during a power failure.