Originally Posted by Boncuk

Hi MrAl,

sorry for the late reply. I assumed nobody was interested in the threat anymore.

I don't know exactly what you mean saying "at some sub cycle pulse width". If you understand firing a triac randomly there is a lot of noise and can also kill a motor. The triac works alright for a couple of cycles and then it heats up and misfires in rapid sequence making the motor change rotation at full speed, which in turn overheats the motor rapidly.

I tested that behaviour with a 5KW motor and a big radial fan connected to it. The change of rotation almost broke the shaft with the heavy 'fly wheel'.

Hans