US 3,937,937 A · Primary power fault detector

Abstract

Data processing and computer systems require continuous monitoring of the primary alternating current power. A power failure must be detected very quickly (within a fraction of a cycle), so that the contents of a volatile memory can be quickly converted into a nonvolatile form. This must occur before power system storage is expended and control is lost. RMS power direction is developed by the product of voltage and current with an integrated circuit multiplier device. When power fails, the circuit indicates a power flow reversal or power equals zero from the detected system current times voltage factor. A retriggerable one-shot in conjunction with a NAND gate is utilized to detect the instantaneous voltage drop to zero and current reversal in order to energize other circuits to protect such volatile data in the event of a power failure.

Claims18

Dependent claims

A power fault detection system comprising:

first means for detecting applied voltage and generating a voltage sensed signal, second means for detecting applied current and generating a current sensed signal, multiplier means for multiplying the voltage and current sensed signals, circuit means coupled to said multiplier means for generating predetermined width signals in response to the output from said multiplier means, and logic circuit means coupled to the output of the circuit means and the output of the multiplier means for detecting the logic level of said outputs, said logic circuit means remaining in a first logic state at an indication of power flowing in a first direction in said system and switching to a second logic state at an indication of power flowing in a second direction in said system.

Dependencies are inferred from the claim text.

Primary power fault detector

Life of this patent

Primary power fault detector

Life of this patent

Abstract

Claims18