Abstract: A rectifier plant controller is combined with a continuously operating feeder monitor option in order to provide feeder line data on demand. The feeder monitor option continuously monitor feeder lines selected by the rectifier plant controller and stores the data acquired in a memory accessible to both the feeder monitor option and the rectifier plant controller. The rectifier plant controller can recover the data upon request at any time.

Abstract: A rectifier plant control system includes a stored program of a master control to control operation and monitor rectifier plant conditions. The master control is designed to cooperate with optional control systems to accomplish new operations without requiring modifications to the stored program control of the master control. One such optional control system permits accessing the master control from a remote location.The optional control system includes an associated stored program which is utilized by the master control to accomplish the option. This associated stored program is in an address field of the stored program of the master control and is executed by the master control.

Abstract: A power train of an uninterruptible power supply selectively transforms its load from a primary source of power to a reserve source of power under control of a stored program control operating in real time. A microprocessor operating in conjunction with a prioritized interrupt controller and a plurality of external counters monitors and responds to signal conditions existing at various points of the power supply. In particular, the amplitude of a primary AC voltage source is sampled at precise angles of the sinusoidal waveform in response to a comb pulse waveform generated to conform to the actual period of the primary AC voltage. The frequencies range is determined by comparing a count interval to the period of the primary AC voltage. Relative power flow from the primary AC voltage source and a reserve AC voltage signal is controlled by relative phasing of the two signals.

Abstract: A power train of an uninterruptible power supply selectively transforms its load from a primary source of power to a reserve source of power under control of a stored program control operating in real time. A microprocessor operating in conjunction with a prioritized interrupt controller and a plurality of external counters monitors and responds to signal conditions existing at various points of the power supply. In particular, the amplitude of a primary AC volatge source is sampled at precise angles of the sinusoidal waveform in response to a comb pulse waveform generated to conform to the actual period of the primary AC voltage. The frequencies range is determined by comparing a count interval to the period of the primary AC voltage. Relative power flow from the primary AC voltage source and a reserve AC voltage signal is controlled by relative phasing of the two signals.

Abstract: A power supply system having a plurality of individual power supplies utilizes a master control to periodically compensate for errors in individual power supplies. The master control is periodically coupled to individual power supplies by multiplexing means to provide compensation signals to counter drifts and errors due to varying circuit parameters therein.

Abstract: An uninterruptible power supply includes a digital control circuit to control the transfer of power from a primary and a secondary power source to a load circuit to be energized. The digital control circuit controls through digital techniques the relative phase angles of a primary power signal, a secondary power signal, and a load signal to advantageously minimize the power drain on an idling secondary power source when the primary power source is active and to minimize transients in the load signal when converting from one power source to another.

Abstract: A power supply load transfer system reduces the transients produced at a moment of transfer by reducing the first and second half-cycle durations of the reserve signal output following the moment of transfer by equal amounts so that a previous phase lag between a primary signal and the reserve signal is eliminated.

Abstract: A digital counter driven by a stable high frequency source generates a periodic signal synchronized to an external signal source. Gating circuitry responsive to particular digital counts, accumulated by the counter, defines precise quantized time intervals. The external signal is examined during these quantized time intervals for the occurrence of significant cyclic events such as zero crossing. A single occurrence of cyclic event is determined during a first time interval while successive multiple occurrences of the cyclic event are searched for during a second but smaller time interval. In each instance failure of the event searched for activates corrective circuitry to inhibit synchronous oscillation with the external signal source.

Abstract: An alarm circuit to monitor a periodic signal source for an occurrence of a short-circuit condition detects the entry of the instantaneous periodic signal magnitude into a predefined window bounded by an upper and lower threshold. The duration of the entry is timed to determine if a short circuit has occurred.