Impulse Strength Measurement: A New Technique for Analyzing Power-Supply System Performance Under Actual Field Conditions

Abstract

"Impulse Strength" is a relatively new parameter, having been defined officially as "the area under the amplitude-time relation for the impulse". In power systems, impulse strength is measured in volt-seconds, and it can be a critical factor in determining the "worst-case" performance of power-supply regulators, "line conditioners," or so-called "uninterruptible" systems. Mathematical analysis of the effect of an impulse on a typical filtered power supply shows that the amplitude of the transient at the output is almost directly proportional to the volt-second area (impulse strength) and virtually independent of the peak impulse amplitude. Another example relates the impulse strength, its source impedance, and the load's breakdown impedance to the destructive power of an impulse. With the recent advent of instrumentation for measuring and recording impulse strength over wide ranges, it is now posible to test systems "in situ". It is also now feasible to write power-supply, UPS, and system specifications so that the reliability of these systems is assured, even in environments having high impulse incidence and strength.