Soft Starters Suitable for AC Induction Motors
November 18, 2011—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 22A to 482A sizes, are suitable to control three-phase AC induction motors with a wide variety of motor loads. This series is a suitable substitute for a Star/Delta starter as it fits into a similar footprint, simplifying installation. 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 four or seven fault types: SCR or Power Supply, Overheat, Control Power Supply, Bypass Relay Failure, Shearpin, Overload, and Overcurrent. It's intended 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. Backed by a two-year warranty, SR33 series soft starter prices start at $490. A heat-shrink insulation kit designed to maintain UL compliance when connecting field cables is available for $8.
The Stellar SR33 series can control three-phase AC induction motors with a wide variety of motor loads.