debounce

[hungry1]

Hello
Is it possible to make a debouncer circuit for pressure switch
contactors that operate on 240v?
Thanks,
curt

 

[Phil Hobbs]

hungry1 wrote:

Hello
Is it possible to make a debouncer circuit for pressure switch
contactors that operate on 240v?
Thanks,
curt

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

 

[hungry1]

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:

hungry1 wrote:

Hello
Is it possible to make a debouncer circuit for pressure switch
contactors that operate on 240v?
Thanks,
curt


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

 

[John G]

"hungry1" <hungry1@fastmail.fm> wrote in message
news:52dc197c6fd8463203135d08cce3faff@news.teranews.com...

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:
hungry1 wrote:

Hello
Is it possible to make a debouncer circuit for pressure
switch
contactors that operate on 240v?
Thanks,
curt


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

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.
--
John G

Wot's Your Real Problem?

 

[Paul Guy]

On Thu, 27 May 2004 17:20:41 GMT, hungry1 <hungry1@fastmail.fm> wrote:

Hello
Is it possible to make a debouncer circuit for pressure switch
contactors that operate on 240v?
Thanks,
curt

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