May not be clear to everyone..P1 and P2 open on over temp. They should be wired in series with the starter coil. Most are self-resetting when the motor cools, but some may still require a manual reset. I'll never admit to it, but sometimes the overtemp switch opens and won't close, so SOME people have been known to just hook the wires going to P1 and P2 together. Disassembling the motor to replace the switch is not usually a popular option. But you didn't hear ME suggest it.:happysad:
Yep like I posted in post 7
What I don't see is any overload protection that is in-line with the supply lines, I don't think that the thermo protection can be treated as an overload, and they even recommend that you use a magnetic motor starter, which is what I would use rated for a 1hp motor, they seem to imply that all you need is a contactor for overload protection with the P1 and P2 in series with the coil but I do not think this would meet the requirements of article 430 which wants something monitoring the current to the motor not its temp?
Heres what they state in their PDF
units have pilot duty thermal protectors requiring only the
addition of an external contactor for overload protection, however, magnetic motor starters are recommended.
Ring compressors have been around for a while now and have been used for about everything from blowing bubbles in hot tubs, aerators for small ponds to vacuum pumps for material handling, one thing I have noticed with them is unlike a centrifugal blower or water pump, a ring compressors current goes up as the air flow is blocked off, it's not much but it can overload the motor, most centrifugal blowers or water pumps actually drop current as the air flow or water is blocked, this is because they are no longer moving as much mass then when it is fully moving the air or water, but a ring compressor is about as close as you can get with a centrifugal blower to a positive displacement compressor with out it being one, it is the design of the very close tolerances between the impeller and housing that forces the air to flow in one direction so it just doesn't fling the air out like a centrifugal blower does, this makes it a very good choice for a vacuum pump where you need a steady constant vacuum to hold product in a suction cup like pulling eggs from key flats, their 10 and 20hp pumps can achieve a 110 IN,H2O which was unheard of with a centrifugal pump, before their development only a positive displacement compressor could achieve that much vacuum suction which many are of the vane design which has allot more parts to wear out, when I worked for an automated egg processing plant that used vane pumps to remove the eggs from the key flats that came in on trucks from the farms, they would struggle getting even 40 In's H2O, 110 In's would suck the egg empty if we had them back then, we were always rebuilding them because the vanes would wear out regularly and the vacuum would drop off causing the eggs to fall off the suction cups.
