Detector for detecting voltage breakdowns on the high-voltage side of an electric precipitator

Claim 1

In a detector for detecting voltage breakdowns on the high-voltage side of an electric precipitator coupled to the detector, the voltage of the precipitator being supplied from an a-c network through a thyristor control circuit coupled to said a-c network, a high-voltage transformer coupled in series relationship to said thyristor control circuit, and a rectifier coupled in series relationship to said high-voltage transformer, said precipitator being coupled in series relationship to said rectifier, and said detector continuously comparing characteristic parameters of successive half-waves of periodical variations of the voltage at the precipitator, a predetermined deviation between successive characteristic parameters being a criterion for determining a breakdown of the precipitator voltage, the improvement comprising first means, coupled to said precipitator, for determining at fixed points in time individual values of the precipitator voltage on the decreasing flanks of the precipitator voltage half-waves, second means, coupled to said first means, for storing the precipitator voltage values determined, and third means, coupled to said second means, for comparing the precipitator voltage values determined with respective individual precipitator voltage values determined for a successive half-wave at corresponding later points in time, said second means comprising at least one storage amplifier, and said third means including at least one difference detector, coupled to said storage amplifier, to which said precipitator voltage values are transmitted and control means coupled to the precipitator and said storage amplifier, synchronized with the harmonics of said precipitator voltage, for controlling said storage amplifier and said difference detector.