The controller referred to is called a Star/Delta starter and is very common over here in the UK. As said it reduces start currents but is also beneficial to starting torque.
The system Starts the motor in Star configuration and the contactors are electrically and mechanically interlocked to prevent both connection types from being energised at once.
When the start signal is initiated as well as the Star contactor being pulled in a timer is also set running, the time at which this is set depends upon the characteristics of the drive system being driven, it is set so that the system has enough time to achieve full speed and consequently the start current will have now dropped off, at this point the timer drops out the Star connected contactor and pulls in the Delta connected contactor and the motor will be heard to accelerate a small amount again but the big difference is that because the drive system is already running then the initial Delta connected current will be much reduced compared to if it had been started from rest in Delta.
Hope this helps someone