At no load, I connected a 380V motor to start in the star connection for 5 seconds and thereafter change to the delta connection. I understand that torque will change since the current will change as well. In fact, the torque should increase as the connection changes from star(wye) to delta... But what about speed?
When I look at it, it seems as though the motor actually rotates faster when the starter switches to delta. However, I've been told that speed remains the same.
I do not have access to a tachometer to test it myself, so it's hard to tell. Does speed increase as well or does it remain the same?