Abstract: Method and apparatus for providing alternate current paths to a junction through different sets of gate controlled SCRs coupled to the junction. The method starts with the step of initiating a switch from an active set of SCRs to an inactive set by removing a gate signal from two parallel connected, opposite sense current carrying SCRs which in combination carry AC current in either direction. Removal of the gating signal is often initiated, for example, in response to an indication that one alternating current source is faulty so that a switch to a second source is initiated. Current is then sensed through the two SCRs of the active set to determine a current carrying state for each of those two SCRs. After the state of the current carrying SCRs is determined the current carrying state of the SCRs is confirmed during a delay time period.

Abstract: Method and apparatus for providing alternate current paths to a junction through different sets of gate controlled SCRs coupled to the junction. The method starts with the step of initiating a switch from an active set of SCRs to an inactive set by removing a gate signal from two parallel connected, opposite sense current carrying SCRs which in combination carry AC current in either direction. Removal of the gating signal is often initiated, for example, in response to an indication that one alternating current source is faulty so that a switch to a second source is initiated. Current is then sensed through the two SCRs of the active set to determine a current carrying state for each of those SCRs. After the state of the current carrying SCRs is determined the current carrying state of the SCRs is confirmed during a delay time period.

Abstract: A digital signal processor implemented monitoring circuit for detecting phase and magnitude disruptions in multi-phase alternating current input signals. A phase lock loop receives multi-phase alternating current input signals and provides one set of alternating current output signals in phase with a time average of the multi-phase alternating current input signals and provides a second set of alternating current output signals phase shifted in relation to the first set of output signals. In a three phase system the phase lock loop provides six alternating current signals. A demodulation circuit multiplies the first set of output signals from the phase lock loop circuit with the multi-phase input signals to produce demodulated sets of signals. An output circuit coupled to the demodulation circuit sums the first set of demodulated signals to provide a first source quality signal. The second set of demodulated signals is also summed to provide a second source quality signal.

Abstract: An induction motor operating system having a pulse width modulation operating system and a time domain signal generating system.The induction motor is operated from the time domain system to provide extremely large motor starting forces compared to the nominal motor force. Opposite ends of each of first, second and third motor windings are connected across a D.C. power supply and individual power supply. Waveforms are supplied to said respective motor windings during a predetermined brief interval. The first waveform, supplied to a first winding, is configured such that current initially flows through the first winding to establish a first magnetic field in the motor. The second and third waveforms are configured so that current is supplied to the second and third windings after establishment of the first magnetic field to establish second and third magnetic fields reacting with the first magnetic field to create a motive force acting on the moving element of the motor.