Soft-starts optimise power factors dynamically

Baldor has introduced two ranges of soft-starts: a programmable range that can optimise the starting profile to suit the application; and a low-cost range for standalone use or fitting inside motor cabinets.

The high-end MD series can optimise a motor`s power factor (PF) dynamically when it runs at partial load, by measuring the PF at start-up and adjusting the firing angle of the power control devices to improve the PF as the load decreases. The soft-starts can be programmed either via a front-mounted keypad or an optional remote 32-character keypad. Users can choose from a list of common profile types, such as pumps with a kick-start, high torque loads, conveyers and so on. Alternatively, they can program custom profiles. The soft-starts control loads from 9-900A (4-900kW) for 208-460V, 400-575V or 500-690V, 50/60Hz three-phase motors.

The simpler SM series provides a switch-selectable choice of ten pre-set soft-starting profiles for applications including pumps, compressors, fans and conveyors. These soft-starts have an electronic "shear pin" to protect against over-currents. They cover the range 5-242A (2.2-132kW), for 230V or 400-460V, 50/60Hz three-phase motors.