debounce

You want to debounce a _contactor_? Debouncing is a sensing issue, not a control issue. If your contactor is chattering, consider using a big solid-state relay instead.

Cheers,

Phil Hobbs

Trying to save the contacts, they get a LOT of use, they burn out very rapidly from arcing. The water pump is in use 24-7-365. Any ideas? I live on an island where there is not too much stuff available.) Thanks, curt

Phil Hobbs wrote:

burn out very

stuff available.)

switch

sensing issue, not

consider using a big

If you could just double the hysteresis of the loop you would double the life of the contacts.

No knowing how your pump is fitted up I can only suggest and you can turn it into practice if possible.. Double the distance between turn off and turn on by whatever mechanical means or, Double the size of the reservoir if that is where the switch is. Whatever you do increase the length of each ON cycle and thereby increase the OFF time. A Solid-state relay, as already suggested, would reduce the current thru the contacts and thereby reduce the arcing again increasing the contact life.

On Thu, 27 May 2004 17:20:41 GMT, hungry1 wrote:

If this is for a water supply, I'd check to see if your air reservoir has run down (causing rapid on-off of water pump). There should be a few adjustments to set the pump-on to pump-off differential on your pressure sensor. They may be set too close. For house water pumps, the differential is often about 20% or more differential (10-15 psi differential at 50 psi delivered). How long does your pressure switch last? The water pump controllers cost $20-30 (here), and I find they last 5 -15 years. The water is full of iron here, they usually jam full of sediment after that time, and seldom fail from contact wear. You can also put in snubbers to reduce the arcing generated by the inductive kickback of the motor when the contacts open. I've seen them for low powered circuits, but not for something like a 1/2HP motor. In any case, I wouldn't trust them, since if they fail, they'd probably catch on fire. I would imagine you could get MOV's that are rated for this application, and place them across the load. You need something to dissipate the energy "dumped" from the inductance of the motor when the contactor opens. I wouldn't trust MOV's either.... they start to change after a while, especially if you give them a lot of transients like you'd see in this application. From what I remember, you need SOME arcing to keep the contacts clean. Power relay contacts use a cadmium alloy that flash clears the gunk on the contacts when they arc. This gives power relays a long contact life, they'd otherwise gunk up and and give intermittant connections, or worse, give a bad connection, fry the contacts right off, and start a fire.

-Paul .............................................................. Paul Somewhere in the Nova Scotia fog ANTISPAM - Please remove the m's in my email address