Abstract: A main and an auxiliary energy supply device supply energy to a load normally and during disturbances of the main supply respectively while, for bridging brief disturbances in the load supply, for example naturally brief disturbances or during the short time when a disturbance has begun and the auxiliary supply has not yet come into operation, there is provided an energy store which can receive and store energy from the main supply and make this stored energy quickly available to the load. A control logic system controls the main and auxiliary supply devices and the storage means to ensure substantially constant energy supply to the load. The disturbances in question may comprise voltage rises or reductions and/or waveform distortions for example.

Abstract: Two condition index variables are used for controlling operation in such a manner that one of the variables is kept as close as possible to a minimum value, while the other is held within an assigned range. Both condition index variables depend on the rate of flow of the flushing liquid through the working gap, on the interval between discharges in the gap or on the duty cycle or repetition frequency and amplitude of the discharge pulses. The condition index variable held to a minimum may be the integral of the square of the error signal from the regulating circuit of the electrode advancing drive, the integral of the square of the acceleration of electrode movement or the quotient obtained by dividing the square of the error signal by the square of the gap current. The regulating value to be held within an assigned range is a calculated breakdown potential defined by the relation of the variation of the error signal to the variation of the electrode spacing.

Abstract: In order to provide respective series of control signals for controlling separate items of apparatus, some of which may be redunant, there are provided a plurality of independently operable signal generators and a plurality of gating circuits connected to the generators and each operable to produce a respective control signal when it receives at least a predetermined number, dependent upon a chosen degree of redundancy of the generators, of correctly timed signals from the generators. Each generator is provided with a phase comparator type timing control device which adjusts the generator if its signals go out of synchronism with those of the other generators. The apparatus to be controlled can be a computer, a multiple-rectifier power supply or the like, and in connecting lines between various parts of the control apparatus and the controlled apparatus isolating devices can be provided.