The Siemens 4EU3951-8UB00-0A is a three-phase mains choke (Netzdrossel f. FU) designed for the input side of a frequency converter drive. Its job is to smooth line current, limit harmonic distortion, and reduce voltage notching on the supply — a standard line-reactor role for a 480 V AC, 50/60 Hz three-phase feed. The 1260 A rated current (1400 A maximum) and 0.01 mH inductance place it squarely in the heavy industrial drive class, sized for a large motor load — think multi-hundred-kilowatt pumps, conveyors, or compressor trains. Go much higher and you lose torque headroom; much lower and the harmonic filtering drops off. This one hits the sweet spot for general-purpose drive protection.
Thermal and environmental limits
Rated for 40 °C ambient, thermal class H. Coil power loss 540 W, iron core 190 W. IP00 open-frame.
The part carries UL/CSA recognition per EN 61558-2-20, which covers safety requirements for chokes and reactors. That means it is accepted for North American panel builds without a separate UL evaluation. No RoHS or REACH statement appears in the available documentation — if compliance documentation is required for your quality system, request the manufacturer's declaration at quote time.