Pressure Switch chatters at end of cycle/ shut-off
by Valentino Mitchell
(San Francisco, ca)
I have installed several different shut-off switches from square D to Furnas and now I am trying an Ashcroft with a Ray Pressure Snubber.
My problem is repeated for each switch I install.
They work initially and then fail by loosing there adjust ability and chatter at the contacts.
I have 2 - 5HP control air compressors in series going through an air dryer into a 200gal receiving tank.
My kick in pressure is 75psi and my kick out pressure is 110psi. I have new check valves and my compressors have been maintained quarterly since being put on line.
The Ashcroft (installed 9/12/09) is now starting to chatter at the end of the cycle, causing the alternator to cycle the off-line compressor briefly then back to the currently running compressor; so I get chattering at the starter.
I am using the switching the starters coil voltage only that runs through an alternator. The alternator is new and mechanically latches the contactor alternately as the coil control voltage drops.
I also have a second low air switch installed (with a snubber) as a low air switch which comes on at 70psi and off at 95psi. The low air is not active when the Ashcroft switch chatters at the end of the cycle.
Very frustrating because they work initially then stop. The Ashcroft is 5x the cost but is rated for greater differential adjustment and has much higher tollerances including vibration. On the note of vibration, I have the Aschcroft mounted securely with uni-strut.
I have contacted Furnas and they could only suggest a snubber, which I have installed.
Please help if you can.
Bill answers...
hello Valentino. Nice to hear from San Fran, and thanks very much for visiting my site.
It's my opinion that the pressure switch chatters normally when the points are wearing out. Have you examined the points in your pressure switch to see if that's the case?
If so, then I'm wondering about their voltage and amperage rating? Check that out too.
Anyone else have any advice on this issue for Valentino?
Cheers,
Bill
