It is also preferable that in relation to a number of loads to be switched on at time intervals, the voltage is always set to the highest of the values concerned. If a load is switched on at any arbitrary time-point and starting from an arbitrary voltage, the voltage can be increased to the first value. If now a further load is to be switched on before the predetermined time interval after which the voltage should be reduced to the second value has elapsed, then the first voltage can be kept at the first value. The predetermined time interval can then be measured from the moment when the further load is switched on. In this case the voltage is only reduced when no switch-on process of another of the loads connected in parallel precludes it. Corresponding behavior can be produced if a load is to be switched on during a waiting time interval which lapses before the voltage should be reduced to the third value. In another embodiment it is also possible to prevent the first value from remaining set for longer than a predetermined time due to the re-triggering described. This can prevent overloading of the load.

It is also preferable for the voltage to be reduced to a fourth predetermined value which is lower than the third predetermined value when no load is connected to the terminals. In particular the fourth value can be zero, so that the voltage is switched off when no load is connected. A control device for applying the controlled voltage at the terminals can thereby be treated with greater care and electrical energy can be saved.

Preferably, at least one of the values is determined on the basis of an electrical resistance connected between the terminals. In this way the operating conditions of one or more inductive loads can be reacted to more effectively.