Abstract: An uninterrupted AC supply includes an AC to DC converter having several DC storage devices which maintain a constant DC voltage in the event of a failure of several cycles of the AC source. Each of the storage devices is connected to a separate branch circuit. Each branch circuit includes a transistor that is driven in a linear manner during a portion of a quarter cycle of an AC reference source, so that only one branch conducts current at a time. The DC voltage supplied to each branch and the conducting interval of each branch are such that equal energy dissipation occurs in each branch during each quarter cycle. To enable only one set of branches to be used for opposite polarity variations of the AC reference source, the current from all of the branches flows to a single node, then to opposite terminals of a center tapped transformer primary winding via a pair of switches.

Abstract: Three-phase power susceptible of having different line to line input voltages in the wye and delta configurations is converted into a three-phase wye output, each phase of which has the same line to line voltage for all of the predetermined input voltages. A three-phase transformer has a secondary winding connected in a wye configuration. No switches are connected to the secondary winding. A primary winding of the transformer includes, for each phase, first and second coils, each having a single tap between a pair of end terminals. The terminals and taps are selectively connected in series with each other. The end terminals are selectively connected in parallel with each other. In certain of the situations all of first end terminals of first coils for each phase are connected to the line voltages. In others of the situations, predetermined first end terminals and taps of predetermined coils are connected to the line voltages and the first terminals and taps of other coils are connected to a neutral terminal.

Abstract: A circuit for attenuating interfering voltage excursions occurring in either the common mode or transverse mode. An isolation transformer having primary and secondary windings separated by a conductive grounded shield has connected across one or both of its windings a shunt path comprising a capacitor in series with a breakdown device of predetermined bi-directional threshold conduction level with a dead band.

Abstract: An AC power line transient suppression circuit comprises a bi-directional series breakdown element in combination with a series inductor and a shunt capacitor.

Abstract: Suppression circuit for transient noise pulses in which the magnitude of the pulse is limited to the threshold value of a selected breakdown device that is equally effective with voltage excursions of either polarity, and which includes means to reduce the high frequency content of the noise pulse and radically attenuate any tendency for oscillation.

Abstract: Circuit for reducing voltage oscillations created by transient pulses in the supply circuit in which a voltage-sensitive breakdown device is placed in series with the capacitor of an inductor-capacitor low pass filter. The breakdown device, having a finite threshold, provides a discontinuity in conduction during the noise pulse excursions to thereby damp any resulting oscillations.