Can Soft-Starters Help Save Energy?

This article describes results of an experimental evaluation of seven commercial soft-starters used with three motors of different power ratings. Several performance indicators have been measured and compared to illustrate operation of soft-starters and assess their energy-saving capabilities. Three standard squirrel-cage induction motors, rated at 3 kW, 7.5 kW, and 22 kW, were used. Several European manufacturers provided soft-starters for the investigation. Tests were performed under the steady-state and transient operating conditions.