... and displays real time AC phase voltage, line voltage, and current with LED display in 3P3W or 3P4W network. It is ... DescriptionYD9120:3 phase current, voltage input, 4 bits display,YD9121:3 phase current, voltage input, 4 bits display + one RS485,YD9122:3 phase ... current, voltage input, 4 bits display + one relay contact output, ...