Caution
kW ratings based on current limit value of 350%. Product should always be selected by Motor Full Load Current
Allen Bradley
Soft starters were developed to overcome the drawbacks of direct on line (DOL) and star-delta starting of single and three phase a.c. induction motors, such as high starting currents, voltage peaks and mechanical snatch.,Soft starters achieve these benefits by controlling the voltage applied to the motor at starting, giving a reduced but controlled starting current and torque to meet the requirements of the motor-driven load. From this starting value the voltage is gradually increased to full value via adjustable ramp times.,Typical applications that would benefit from the use of soft starters include conveyor belts, pumps, mechanical handling equipment, air conditioning systems, compressors, grain dryers and fans.,In addition to the above the installation of a soft starter provides the following major advantages:
Reduced starting torque minimising stress on motor, bearings, drive belts and chains
Prolonged equipment life and reduced maintenance
Minimises voltage dip problems which may affect sensitive electronic equipment on site
Energy saving through reduced peak kVA
Allows minimum cable conductor size
Elimination of high current transients: when a 3-phase motor switch