Electronic overload detecting device

摘要

A device for detecting a persisting electrical overload in an electrical system includes means for monitoring an electrical parameter in the electrical system and for generating an electrical signal whose magnitude represents the instantaneous absolute value of the parameter, reference means which generates an output signal of predetermined value and which develops, in cooperation with the monitoring means, an electrical signal whose magnitude represents the amount by which the magnitude of the absolute value signal exceeds the predetermined value, integrator means to integrate the aforementioned electrical signal and to generate an output whose magnitude includes a component representative of the product of the electrical signal and a time-increasing value that represents the duration that an overload has persisted; and comparator means to continuously compare the magnitude of the integrator output signal with a second preselected value and which generates an indicative output whenever the integrator output signal exceeds the second preselected value.