Induction Motor - Starting with Star/Delta Switch Configuration
Last update: February 20, 2022
Two induction machines (IM) are compared. The first one is started with a star configuration and is switched to a delta configuration at t=2s. The second IM is started directly with a delta configuration. Both machines are set to torque mode (S=0), and are switched on via main breaker at t=1.0s.
The benefit with starting an IM with star configuration is that the inrush currents are reduced by approx. 1/3 (see plot "Inrush Current Comparison" below). This can be seen in the IM comparison plots. The second IM draws a larger start-up current and has a larger torque than the first IM. Although the first IM as secondary current and torque spikes at the switch from star to delta at t=2s, these spikes are not as large as the initial spikes seen in the second IM.