Hi,
I would like to compute the heat dissipation of a thyristor which is used in Soft-Starters. As far as I know, heat dissipation in thyristors is composed of the two terms, P=V.I(av)+R.I(av)^2. To understand each term of this equation, I am looking for some references in which there is a good description for heat dissipation calculation of thyristors.Thank you in advance for your help.

 

This info should be on your data sheet...........

Otherwise, depending on what you are softstarting, anywhere from a "Dremel" hand tool, to a 5 hp 3-phase motor fer instance.........I would start with a heatsink that can dissipate at least ten watts, and use a infrared spot thermometer[ pyrometer ] if you prefer, and closely track temp rise on at least ten start cycle, and re-evaluate your heatsink requirements accordingly.

Calculations are ok, real time operation doesn't always listen, as there are no dependable mathematic variations to cover how "joe schlameel" runs the equipment