Posted by John B [68.69.26.160] on Monday, January 06, 2014 at 22:15:00 :
In Reply to: Re: Sounds like you are set posted by Greggg [166.182.3.9] on Sunday, January 05, 2014 at 19:35:32 :
Thanks Greggg for the vote of confidence.
One thing that I might add here is that the magnetic motor starter for the larger motors in principle does the same function as the starter relay ("solenoid as some call it")does in your vehicle. Your key switch, or the push button on the dash (as in my dad's old 52 Ford 1/2 ton) sends momentary power to the magnetic coil of the relay (motor starter.) The larger power contacts of the relay or motor starter (which are capable of carrying high amperage) close and they pass the power to the starter motor of the vehicle. The engine starts, you turn the key back or take your finger off the button and the starter drop out.
With your air compressor when the pressure drops, the contacts in the pressure switch close and they send control power to the coil in the magnetic motor starter. It closes the heavy duty contacts within and sends the line power to the motor. The motor runs until the pressure switch reaches it's prescribed setting and opens the contacts, breaking power to the coil. The big contacts open, the motor stops.
Therefore you can use a 2, 3, 5 hp. rated pressure switch to control a 7.5 , 100, 1000, or 2000 hp motor. Of course in industry there are many other methods of operating and controlling electric motors using start -- stop with maintaining contacts, PLCs, etc,etc. these days.
Aren't we so fortunate that our predecessors had the most of this all worked out for us before the most of us were even born, and all we have to do is try to understand it.
Now if I could just understand what makes the pistons go up and down and the wheels go round and round on the 1947 WDX. HA HA. JJB.