Just about every time I see the word transformer I see the work "electrical isolation" but I really have no idea what it means. Obviously there are is no direct electrical connection but whats the big deal with this? Why is it important to isolate the mains, say, with an isolation transformer when it decreases efficiency?
I just don't see the point of isolating something just to isolate it.. there has to be a very good reason but no one seems to mention it. Like one could use AC to power a motor that powers another motor that generates AC and hence there is an electrical isolation... but what good is it?