NK Technologies APN Series Power Monitors measure three phases of current and voltage and compute fourteen values necessary to track power usage. The monitor uses current transformers to measure the amperes. The line voltage connects directly to the transducer, up to 600 VAC. The result is 14 data points in the RS485 Modbus RTU format. NK Technologies APN -R Series Power Monitor measures three phases of current and voltage and computes fourteen values necessary to track power usage.