S21HSNA-RNNM-03 Pacific Scientific
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The Pacific Scientific S21HSNA-RNNM-03 is a 6-pole Neodymium magnet brushless servo motor from the S Brushless Motors series. This NEMA 23 motor has a continuous stall torque of 0.5 Nm and a peak torque of 1.36 Nm. It features a size 21 frameless resolver as its primary feedback device and has a motor weight of 1.4 kg.
Internal Product Review
The S21HSNA-RNNM-03 is a 6-pole neodymium magnet brushless servo motor in a NEMA 23 frame. Continuous stall torque of 0.5 Nm and peak torque of 1.36 Nm support responsive motion control and dependable overload performance. A size 21 frameless resolver and motor-mounted MS connector make this motor a strong choice for compact servo applications.
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Product Description:
The S21HSNA-RNNM-03 brushless servo motor is manufactured by Pacific Scientific and belongs to the S Brushless Motors series. As a six-pole neodymium-magnet actuator, it converts drive current into tightly regulated shaft motion for positioning or velocity control within automated machinery. The compact frame allows direct coupling to small gearheads or lead screws, making the unit suitable for electronics assembly lines, laboratory dispensers, and light material-handling axes where space is limited but dynamic response is required.
During operation, the motor can supply a continuous stall torque of 0.5 Nm, providing a baseline for selecting gearbox ratios and holding loads. Short transients are supported up to a peak torque of 1.36 Nm before thermal limits intervene. The electromagnetic conversion efficiency is characterized by a torque constant of 0.2 Nm/A RMS, which links commanded phase current to delivered shaft torque. Electrical dynamics are set by a line-to-line inductance of 3.7 mH, which affects current ripple and the bandwidth that the amplifier can achieve. A phase resistance of 3.0 ohms establishes copper loss at rated current and influences the voltage margin required from the inverter.
The rotor’s reflected inertia is only 0.042 kg·m² × 10⁻³, so acceleration and deceleration can be executed with modest drive torque and minimal tuning effort. The total assembled mass is 1.4 kg, which eases installation on moving carriages or belt drives. The housing conforms to the NEMA 23 dimensional code, and the resolver provides absolute angular feedback without a secondary feedback device. With a back-EMF constant of 0.13 V RMS/(rad/s), the motor remains compatible with low-voltage servo amplifiers. An integral MS connector simplifies wiring, while the single-stack H winding helps minimize thermal rise. The shaft is supplied without a brake or seal, making it appropriate for applications that do not require passive holding or protection against liquid ingress.
