What it is and what it does
The Siemens 4EU3921-7BA00-0A is a three-phase commutating choke — a line reactor — for converter applications. It limits current rise and reduces harmonic distortion on the AC side of a variable-speed drive or rectifier. Rated for 500 V AC at 50 Hz, it carries 800 A continuous AC current (720 A operational) and peaks at 1 000 A. The 35 µH inductance with a 4 % relative inductive voltage drop defines the smoothing and commutation notch filtering it provides.
Key ratings and what they mean for fit
The 800 A AC maximum current at 50 Hz sets the thermal limit for continuous operation. The 720 A operational AC current is the design point for voltage drop calculations — use that for sizing the cable and upstream protection. The 4 % impedance is standard for drive input reactors; it keeps DC bus ripple and line notching within typical drive manufacturer limits. Power loss splits into 375 W copper loss and 230 W iron loss, totaling 605 W at rated load. That heat must be managed — the IP00 enclosure means no fan or filter; the choke relies on natural convection in the cabinet. Thermal class H (180 °C) insulation gives headroom for high ambient temperatures up to the 40 °C rated ambient.
Physical integration and connection
Dimensions: 0.385 m high, 0.41 m wide, 0.229 m deep. That footprint is substantial — plan for a dedicated mounting plate or sub-panel in the cabinet, not DIN-rail. Main circuit connection is via flat-type terminals, typical for busbar or large cable lugs. Verify busbar hole pattern and lug width against the terminal dimensions before ordering.
Lifecycle and sourcing
The 4EU3921-7BA00-0A carries an active product status. It is recognized under UL/CSA per EN 61558-2-20. Sourced and quoted to order through independent distribution; availability and current pricing confirmed at quote time. For a BOM freeze or a line-down replacement, this is a straightforward RFQ — no last-time-buy window to chase.