Differential Current Sensors targeted for Three-Phase Transformerless Inverters

Vacuumschmelze GmbH & Co. KG (VAC) has added a further model to its family of ac/dc sensitive differential current sensors (DI sensors). The new T60404-N4646-X976 sensor can be mounted on the primary or secondary side of PCB assembly equipment and is designed for three-phase systems. It features four integrated primary conductors L1, L2, L3 and N, plus a test winding. VAC's new sensor is designed for operating currents of up to 50 A. The effective differential current range is typically 30 mA to 300 mA. The measurement range extends to 850 mA.

DI sensors by VAC have operated for many years in transformerless solar inverters. The devices deliver a key safety function by monitoring earth leakage current throughout the entire photovoltaic module and inverter system. As this leakage current contains dc and ac components, an ac/dc-sensitive monitoring unit is necessary. The heart of these units is the VAC differential current sensor, which delivers output voltage proportional to the differential current that is evaluated by the control system of the solar inverter.

Further features of this new DI sensor type are: operation from a simple +5V source, automatic sensor core demagnetization to minimize offset voltage, a range of self-monitoring and testing functions, metal screen against external fields and broad dc frequency range up to 10kHz. This type of three-phase DI sensor with plug-and-play compatibility, offering proven VAC quality and high-accuracy measurement with outstanding long-term and temperature stability, has long been awaited by the market.