324 / | HD | ELECTRICITY: MEASURING AND TESTING |
76.11 | DF | MEASURING, TESTING, OR SENSING ELECTRICITY, PER SE {46} |
76.39 | DF | .~ Frequency of cyclic current or voltage (e.g., cyclic counting etc.) {6} |
76.52 | DF | .~.~ By phase comparison {10} |
76.66 | DF | .~.~.~ With capacitive energy storage {1} |
76.67 | .~.~.~.~ With space discharge device |