I could be wrong here, but you could look up some 3A thyristors and see what what packages they come in.i dont hav to guess bout the current capacity,what i require is a 3 ampere thyristor,i jst want to have an idea of its size,is it anywhere related,or can it b guessed by general experience.
The specs for a TO-220 case is not necessarily the dimensions for a 3 amp SCR. It could be in TO-3 case, a TO-92 case, or some surface-mount variation.can we guess/determine the size of a 3 ampere commercially available thyristor