Soft Starter has faded with the advent of VFD

As regards the soft starters, unless there's been a radical design change, it appears they are all still SCR based as I figured they are, and as such, they generate huge amounts of distortion at start that diminishes to nothing when the motor reaches speed. They have their place in control types that don't require or benefit from variable speed control. In systems where smooth initiation is a benefit with controlled acceleration / deceleration, high inertial resistance needs to be overcome, as well as placement capabilities and varying speeds, soft starter usage has diminished dramatically.

I have a pumping system I designed, used for batch leveling tank control at the Valero refinery in Shenzhen China and in operation for the past eight years at least. This system is registered with IEEE. The flow control used to be with a soft-started constant speed motor, and incredibly expensive valves. Now it's regulated by a variable frequency drive (VFD) for pump speed control, eliminating the need for flow valves and expensive labor for valve changes. There are other examples where VFD has become the option for many reasons, and there are also applications where cost and objective settles the choice as Soft Start. My point in all of this has been how soft starter usage in many industries has faded with the advent of variable frequency drive.