Product Description:

The PMB31D-20200-02 is a brushless servomotor manufactured by Pacific Scientific and supplied within the PMB Brushless Servomotors series. It serves as a torque source in automated machinery, accepting drive current from a matched amplifier and converting it into precise rotary motion under feedback control. Typical uses include indexing tables, moderate-inertia axes, and feeder mechanisms that require accurate speed regulation and stable position holding. Its brushless design also reduces mechanical wear associated with commutator-based motor systems. That operating role makes it suitable for systems that need repeatable starts, stops, and dwell periods without the brush maintenance associated with older motor types.

The motor housing follows the NEMA Size 34 standard, so its 3.4-inch square face and pilot diameter align with widely used gearheads and mounting brackets. Continuous stall operation at 240 Vac is limited by a winding current of 5.4 ARMS, which marks the continuous thermal current limit for applications that hold load for long periods. Rotor position is reported by a resolver, providing sinusoidal feedback that tolerates electrical noise and elevated temperatures better than many digital encoder systems. Electrical power, feedback, and thermal leads exit as flying leads with MS connectors, which support straightforward connection to the matching harness. Mechanical coupling is through a shaft machined with a square key, helping prevent slip between the motor and the driven element during acceleration or reversal. This combination of feedback and connector style supports orderly cable routing between the motor and the amplifier in enclosed machine frames.

For thermal supervision, a built-in PTC thermistor acts as a thermal sensor, changing resistance sharply when the stator reaches its threshold and prompting the drive to reduce current or shut down. The laminated core uses a stack length multiple of 1, the shortest configuration for this motor format, which helps keep overall length and inertia low. That shorter stack is useful on pick-and-place axes that must start and stop quickly without adding unnecessary rotating mass. The motor serves as a compact actuator in installations where limited mounting space and integrated thermal protection are both important.