Originally Posted by
NoNickName
Well, the edge between the two is thinner and thinner, these times.
They were so called high temperature (Air conditioning) twin-screw compressors with built-in oil separator.
And for Josip: it's funny how they weld in seconds. The kriwan protection does not open in time. I personally witnessed two of these while seizing, and it's like listening to a turboimpeller light aircraft when climbing in vertical, until no more noise can be heard except zzzzzzzz and finally clunk of the thermal switch.
Regarding the kriwan int69 and similar, I find them to be the most useless component at all; it didn't ever save any compressor that I came across.
Also, the first version was affected by a bug: when twin screws stop, they counter rotate by high side pressure. At that time, the motor operates as a three phase generator for maybe 2 seconds. The kriwan understands the phases have been reversed and opens the alarm contact. Very annoying, but now it is solved.