This part of EN 60947 applies to a.c. semiconductor non-motor load controllers and contactors intended for performing electrical opertions by changing the state of a.c. electric circuits between the ON-state and the OFF-state. As controllers, they may be used to reduce the amplitude of the r.m.s. a.c. voltage on the load terminals from that of the applied voltage - either continuously or for a specified period of time. The half-wave period of the a.c. wave form remains unchanged from that of the applied voltage. They may include a series mechanicall switching device and are intended to be connected to circuits, the rated voltage of which does not exceed 100