Hello!
It's intrested to me - are the SCR softstarters patented?
Please post your link to patents that are realtive to SCR softstarters.
For example i have found
http://www.freepatentsonline.com/6420848.pdf
http://www.freepatentsonline.com/4482853.pdf
http://www.freepatentsonline.com/6407529.pdf
http://www.freepatentsonline.com/6163129.pdf
May be you have an interested patents link too?

There are probably as many patents as there are manufacturers, in fact, probably more. A lot of manufacturers who started up in the 70s and 80s are now either defunct or have been gobbled up by competitors. You could waste hours sifting through them all. For what purpose might I ask?

Generally speaking, i would like to find the inventor of phase-angle softstart method and first device released on market. And also want to know is the thyristor' alpha angle decreasing method of AC motor start patented?
For examle i would like to make my softstarter for sell. Am i need to buy license on softstart method???

Hello Igneous

Soft starters were commercialized in the 1970s and may have been "invented" even earlier.
The original soft starters were very expensive and only used in very sensitive applications.
The advent of the NASA energy saving algorithm was probably the catalyst for todays soft starters that are commercially competitive against electromechanical soft starters.

Any original and early patents covering soft starters and aspects of the soft starter are now well and truly expired.

In terms of the alpha and gamma control systems, I was using these techniques many years ago and had patents covering aspects of these that dated back to the early 80s if I remember correctly. This is not new technology, although many manufacturers use only one means or the other. The combination of both was being used around the mid 80's so it would be difficult for anyone to claim prior art and make it stick based on current patents.

Best regards,