Allen-Bradley 150-A35NBDC AC Variable Frequency Drive

Allen-Bradley 150-A35NBDC Smart Motor Controller (SMC-2) is an open-style soft-start device for 3-phase motors, designed to limit inrush current and provide a controlled ramp start. It is rated for 380–480V AC input with a 50/60 Hz supply and carries a continuous current rating of 35 A, delivering up to 25 HP at 460 V. This model is intended for use in industrial automation where a soft-start is beneficial to reduce mechanical stress on conveyors, pumps, fans, and other motor-driven loads. The 150-A35NBDC variant aligns with the SMC-2 family and is specified for 3-phase operation at 460 V, making it suitable for applications requiring reduced voltage starting rather than full variable-frequency speed control. While the device is a legacy part that Rockwell Automation has discontinued, it remains encountered in surplus and aftermarket channels and is compatible with systems designed around the SMC-2 architecture. In practice, it addresses starting torque and current spikes without implementing full frequency modulation, distinguishing it from true AC variable frequency drives.