Hey guys, i have just been challenged with the task of drawing a control diagram for an existing chiller, this unit has been modified so many times by so many people that I dont think the chiller knows what it is any more .

My question is there have been 2 timers added to bypass the low pressure switch, is this normal and why would you need to?

Also why does there never seem to be overload protection on compressors?

Sorry for my ignorence but i am a Controls Engineer from Manchester, now living in Canada