Abstract: A method of detecting the presence of a hazardous foreign voltage on a conductor includes the steps of sensing an electric field in the vicinity of the conductor with a first non-contact conductive sensor and sensing the electric field in the vicinity of the conductor with a second non-contact conductive sensor spaced a predetermined distance from the first non-contact conductive sensor. The difference between the electric field sensed by the first conductive sensor and the electric field sensed by the second conductive sensor is determined. The first conductive sensor preferably is shaped as a truncated spheroid. If the difference is less than a predetermined threshold, the sensed electric field is ignored as being induced by a distant source. If the difference is greater than a predetermined threshold, the electric field sensed by the first and second conductive sensors is considered to be indicative of the presence of a foreign voltage on the conductor.

Abstract: A circuit breaker monitoring system for monitoring three-phase circuit breakers includes three channels that convert a respective phase current through a respective set of circuit breaker contacts into a sequence of digital signals each representative of an instantaneous value of current through the contacts. Each channel includes a transformer having a primary winding that receives current corresponding to that through the breaker contacts. A resistor across the secondary winding develops a voltage proportional to the current. An input buffer voltage follower couples this voltage to the input of a high-speed 12-bit bipolar analog-to-digital converter that provides the digital signals. A microprocessor coupled to a 12K RAM working memory, a 4K EPROM that may store breaker monitor software and a 2K E.sup.