Semi-conductor soft starters
The SR33 semi-conductor soft starters are designed to control three-phase ac induction motors.
The Stellar SR33 Series basic soft starters are designed for general purpose applications where traditional across-the-line starting or wye-delta starting would typically be appropriate. The SR33 semi-conductor soft starters, available in 22 A to 482 A sizes, are suitable to control three-phase ac induction motors with a wide variety of motor loads. All units feature two-phase control, easily and separately adjustable motor start voltage and start and stop times, and depending on model, fault indication of 4 or 7 fault types: SCR or Power Supply, Overheat, Control Power Supply, Bypass Relay Failure, Shear pin, Overload, and Overcurrent. Ideal for applications such as pumps, blowers and conveyors, the SR33 series soft starters use thyristors for controlled reduced voltage motor starting and stopping, and then switch to internal contacts for efficient running at rated speed.
– Edited by Chris Vavra, Control Engineering, www.controleng.com