Product Description:

The S21HNNA-RNNE-00 is a 6-pole neodymium magnet brushless servo motor produced by Pacific Scientific in the S Brushless Motors series. It serves as a compact actuator that converts electrical current into controlled rotary motion for positioning axes and material-handling stages in industrial automation. A size 21 frameless resolver provides primary feedback to the drive, and because the unit comes without a holding brake or shaft seal, it is intended for machines that already provide external load holding and protection from surrounding contaminants. The built-in mounting pattern allows the motor to fit older NEMA-frame layouts without redrilling the mechanical interface.

During continuous duty, the motor delivers a stall torque of 0.5 Nm, helping conveyors or tables move smoothly at low speed. Short bursts can reach 1.36 Nm, which gives additional torque during acceleration or indexing moves. A line-to-line inductance of 3.7 mH affects current rise time and can limit the highest practical servo bandwidth. The winding’s phase resistance of 3.0 Ohms contributes to copper losses and affects the RMS current available at a given bus voltage. With a torque constant of 0.2 Nm/ARMS, the controller can relate measured phase current to mechanical output more directly.

Mechanical response is influenced by a rotor inertia of 0.042 kg·m² × 10⁻³, which supports fast reversals while still damping small load disturbances. The square flange matches the NEMA 23 standard, and the motor mass of 1.4 kg reduces load on mobile or vertical axes. A back-EMF constant of 0.13 VRMS/rad/sec allows the drive to estimate speed from voltage if resolver data is briefly unavailable. The motor also uses single-stack construction, H-class windings, and Interconnectron power and feedback connectors, and it does not include secondary feedback.