The Working Standard WS 2330 is a three-phase precision reference meter for electrical power and energy measurement, dedicated to on-site meter testing. The device provides also function of local data exchange with smart meters (data readout). The device is designed for operation in single-, two- and three-phase systems, where it evaluates and displays all individual quantities per phase and cumulative three-phase quantities. Universal inputs can be equipped with any combination of interchangeable precision voltage and current sensors up to 600 V and 6000 A. It contains direct voltage input 300V CAT IV / 600 V CAT III and provides function of supply from measuring circuit. Measurement is based on precision A/D conversion and DSP technology and enables accurate high-speed real time evaluation of all main and informative quantities. Beyond measurement of power, voltage, current and phase the device indicates voltage sequence, evaluates active, reactive and apparent energy and measures distortion and wave-form of measured signals. The device can generate any programmed energy proportional or constant frequency on the impulse output. This unique feature allows precision error evaluation with minimum integration period. The device is equipped with integrated error calculator and meter scanner capturing LED, DISK or Closed Contact output of tested meters and snap switch for simple manual testing. The device can be supplied from internal rechargeable battery, from external power adapter or from car outlet. Function of supply from measured circuit is integrated as a standard. Software for MS Windows enables transfer and presentation of measured data in PC. Optional portable printer enables on-site printing of results or actual display content.