Product Description:

Pacific Scientific manufactures the M21NRXB-LDN-NS-00, a two-phase stepper motor in the POWERMAX II M Motors series. It serves as a positioning element in industrial automation, translating pulse trains into incremental 1.8-degree movements so that conveyors, gauges, or small actuators reach repeatable stops without an encoder. A double-ended smooth shaft lets couplings or feedback wheels be mounted on either side of the NEMA 23 frame.

Because it uses one stack and winding type B, the motor develops a bipolar holding torque of 0.97 Nm while drawing up to 4.6 A/phase in parallel operation. In series connection, it carries 2.3 A/phase, and in unipolar mode it carries 3.3 A/phase. The fixed step angle of 1.8 degrees gives 200 full steps per revolution, and positional error remains within ±1.5%. Class B, 130 °C insulation, 5.5 °C/W thermal resistance, and an operating range of -20 °C to +40 °C support continuous-duty use, while rotor inertia of 0.012 × 10⁻³ kg·m² helps the motor settle quickly after each pulse. A parallel inductance of 1.0 mH with 0.32 Ω resistance balances rapid current rise with manageable losses, whereas the series path presents 4.0 mH and 1.28 Ω for smoother low-speed control.

The NEMA 23 housing is 52.3 mm long and weighs 0.68 kg, which helps keep the motor compact. A 6.35 mm smooth double-ended shaft transmits torque to timing pulleys, and the opposite end can carry a manual knob. In unipolar operation, the motor delivers 3.3 A/phase and 0.68 Nm of holding torque for systems that use simpler drives. Receptacle-style lead-wire connections exit through a NEMA-pattern face, and insulation resistance is 100 MΩ at 340 Vdc to help limit leakage. The single-stack core aids thermal transfer, and the mounting style fits standard NEMA brackets for straightforward installation.