York would not bother with the extreme cost of adding a VFD and not use it to modulate speed. On a Chiller, it might BEGIN at full speed, but will change the speed based on the requirements for coolant flow. If it never changes speed, it was a total waste of money and energy, a Soft Starter would have been a better choice.
When VFD accelerates a motor from standstill, the motor starting current is completely controlled by the VFD at all times. In addition, the motor power factor is also being controlled, so the current going to the motor is almost all going toward creating torque, where as the high starting current from starting a motor Across-the-Line is mostly reactive at first, meaning NOT yet producing torque, until the motor gets to around 80% speed. So using the VFD, you can accelerate the motor without ever exceeding the motor nameplate FLA, so long as acceleration time is not a concern. In a chiller it usually is, so it might go higher to maybe 150% of FLA for a brief time, but never the 600% you see Across-the-Line.
