Product Description:

The SS25 is a synchronous AC stepping motor manufactured by Danaher in the Slo-Syn Synchronous Motors series. As a constant-speed, self-starting unit, it is used in industrial automation to index conveyors, actuate metering pumps, and hold rotary tables at fixed angles without additional feedback devices. By locking its rotor to the power-line frequency, the motor supplies precise rotational increments that allow controllers to advance mechanical loads in equal steps during each half-cycle.

The motor is designed for single-phase operation on a nominal 120 VAC supply at the North American mains standard of 60 Hz. Under these conditions, it develops a holding and running torque of 25 oz-in, which is suitable for light positioning stages or small valve linkages. Line current does not vary with the operating state because the start, run, and stall currents are identical, simplifying thermal calculations for power supplies. Three preterminated leads simplify connection to triac or relay outputs. At startup, the rotor synchronizes within 1.5 cycles, and once locked, it rotates at a synchronous shaft speed of 72 rpm. No separate cooling is required because the laminated frame dissipates I²R losses and helps control the stator temperature when the shaft is blocked.

When powered from a 50 Hz utility grid, the shaft settles at 60 rpm, preserving step accuracy in machinery designed for that supply frequency. The internal winding geometry produces a quadrature phase shift of 90° between the auxiliary and main coils, so the rotating field maintains a constant amplitude during acceleration and load transients. The case temperature may reach up to 100 °C without insulation breakdown, permitting installation in warm enclosures. Deceleration is also precise because the rotor comes to rest within 5 mechanical degrees of the commanded stopping position. This stopping performance supports repeatable motion in pick-and-place and print-registration applications.