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.

Abstract: A circuit for ascertaining the direction of origin of the most significant transient appearing on a electrical power line within a predetermined interval is disclosed. Threshhold comparator circuit (325, 326) are provided to insure that transient polarities needed for the directivity determination are ascertained while the transient impulse is still rising towards its peak value. For any nominal, user-set threshhold (V.sub.2), a lower preliminary threshold (V.sub.1) is automatically set and when the transient exceeds the preliminary threshhold, the transient polarities are determined and correlated to effect a tentative directivity determination which is stored in an input latch (205). When the transient exceeds the nominal threshhold, the directivity determination is transferred to an output latch (211) to be read by an output printing device.