307 / | HD | ELECTRICAL TRANSMISSION OR INTERCONNECTION SYSTEMS |
43 | DF | PLURAL SUPPLY CIRCUITS OR SOURCES {14} |
44 | DF | .~ One source floats across or compensates for other source {3} |
45 | DF | .~.~ With intervening converter {1} |
46 | .~.~.~ Storage battery or accumulator-type source |