Product Description:

The SS250BE is a synchronous stepping motor manufactured by Danaher as part of the Slo-Syn Synchronous Motors series. Designed for direct-line operation, this single-phase unit converts a constant mains supply into precise incremental shaft motion, making it useful for low-speed indexing tasks and regulated conveyor drives in industrial automation. Electrical terminations land on a terminal board for straightforward field wiring. The single-phase configuration simplifies connection to common utility power sources.

The motor is powered by a nominal 120 Vac source and draws 0.6 A RMS per phase when operated on a standard 60 Hz grid. A series capacitor rated at 6.5 µF provides the phase shift required for self-starting, while a 150-ohm, 50-W resistor limits inrush current during energization. Under rated conditions, the rotor settles at 72 rpm, a speed that corresponds directly to the line frequency and internal pole count. The minimum running torque is 250 oz-in, allowing the shaft to maintain motion against friction and process loads without stalling. A rear shaft extension supports a feedback encoder or manual handwheel, and the 2.186-inch mounting pilot locates the frame concentrically with gearheads or machine plates.

The shaft can accept an axial push or pull of 50 lb and withstand a radial overhung load of 25 lb without excessive bearing wear. Dynamic response is influenced by a rotor and load inertia of 0.12 oz-in-s², which balances move-to-rest settling time with torque stability. Couplings must match the 0.375-inch-diameter shaft. The precisely ground journal measures 0.3750 in and includes a flat for secure set-screw contact. Heat generated during continuous operation is conducted through the frame, and sufficient mounting clearance should be provided to allow natural convection around the motor body. Proper alignment of the mounting pilot and coupling also helps prevent unnecessary radial stress on the shaft and bearings during operation.