Abstract: A scheme for providing an output signal approximating a true sine wave representative of a sine wave source voltage from corrupted line voltages connecting the source to a load includes the development of a first signal representative of the corrupted lines line voltage. The first signal is then filtered to reject all but higher frequency components and this filtered output is then combined with the first signal to provide a combined signal which is further filtered to provide a final output signal.

Abstract: A detection system for detecting unintentional impedances between the power conductors and a first node of either a power conversion circuit or a load, the first node typically being an earth ground. The circuit has power level lines utilizing a wye-connected line filter network which has equal impedance values for each leg of the line filter and which defines a first node at the common connection thereof. A different impedance network is also connected in wye-fashion to the power level lines and defines a second node at the common connection thereof. Each impedance leg of the impedance network is also equal in impedance value whereby the second node normally has the same potential as the first node. The potential difference between the first and second nodes is frequency compensated to produce a system output signal indicative of a predetermined value of current in unintentional impedance between any of the power conductors and the first node.

Abstract: A circuit for controlling the rendering conductive of the controlled rectifiers of a power conversion unit to thereby control the power supplied to a load from a source of alternating current voltage employs a single means to sense a prescribed phase relationship between adjacent phase to neutral voltages of the source which means is utilized to develop a digital count representing a time-phase relationship with respect to the point determined. The digital count thus developed is supplied to a memory system to address that system and based upon the contents of the locations within the memory system thus addressed there is provided an output which determines the time and firing sequence of the rectifiers of the power conversion system. This output is then utilized to generate suitable signals which are applied to the rectifiers of the power conversion system to thereby control the power supplied to the load.