The Allen-Bradley SMC-50 Smart Motor Controllers are said to offer a more economical alternative to variable speed drives, and more advanced control than direct-on-line starters.

The controllers (above), which incorporate a newly designed three-phase SCR (silicon-controlled rectifier) power structure, combine advanced monitoring and protection functions, multiple start and stop options, and expandable control inputs and outputs. These can help users to raise efficiency, cut downtime and improve control.

There are nine standard starting modes, six stopping modes and several slow-speed functions. In the traditional starting mode, for example, if the device senses that a motor has reached full speed before completing the selected ramp time, it will switch automatically to providing full voltage to the motor. A patented linear acceleration starting mode is said to offer the lowest starting current profile per start, consistent acceleration times and enhanced control over both torque and speed. For all modes, the controller stores the motor start time and peak current value to help optimise set-ups and performance.

An automatic zero-speed shut-off function can stop a motor quickly without needing extra hardware or feedback devices.