Importance

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Abstract

A circuit for indicating the approximate energy content of the most significant transient appearing on an electrical power line within a predetermined interval is disclosed. An input to a first threshold comparator (326) may be set by the user to mark the nominal minimum amplitude (V.sub.2 ) of voltage transient whose energy content (volt-second area) is to be recorded. The transient impulse voltage integrator (401) is turned on when the impulse amplitude exceeds a preliminary threshhold (V.sub.1) lower than the nominal amplitude (V.sub.2) under control of a second comparator (325) and flip-flop (423). When the transient impulse amplitude equals the nominal amplitude (V.sub.2), a latch (431) reading a digital converter (430) at the output of the integrator (401) is clocked to permit display of the accruing integrator. While the integration proceeds the threshold of the second comparator (325) is increased from V.sub.1 to V.sub.1 ' in accordance with the peak value attained by the voltage impulse and the comparator (325) turns off the integrator (401) when the transient impulse amplitude falls below V.sub.1 ' rather than V.sub.1. This earlier turn-off prevents the integrator from responding to 'trailing ringing' transients.

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First Claim