dslreports logo
site
 
    All Forums Hot Topics Gallery
spc

spacer




how-to block ads


Search Topic:
uniqs
1622
share rss forum feed


alphapointe
Don't Touch Me
Premium,MVM
join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..
reply to Kearnstd

Re: uC Boiler Sensing

I've got the prints for it, it's just a dry contact closure on each of the three alarm relays.

The chiller is 480V 3ph, and when it starts, the contactor pulls in with a sound like a shotgun blast... it's one of those things where you press the start switch and nearly hit the deck anticipating an arc flash...

I'm considering putting a solid state relay across the 120V start/reset switch so we can start/reset the chiller remotely from the web interface to the PLC...
--
"When the hammer drops, the bullshit stops"



alphapointe
Don't Touch Me
Premium,MVM
join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..

1 recommendation

Click for full size
I can't get back far enough for a full picture of this beast...

Everything is online and seems to be working fine. I think I'm going to need a third DA board, though, as each DA board only has 8 digital inputs, and the boilers take up 10 of the 16...
--
"When the hammer drops, the bullshit stops"


alphapointe
Don't Touch Me
Premium,MVM
join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..
reply to alphapointe

Anyone have any ideas on a water level sensor that I can hook up to an arduino to get water level on the cooling tower? I've already got wireless serial radios so I can send the analog reading to the PLC (with another arduino)...

So far, the only thing I've been able to find are float switches, and while a low level float switch would do in a pinch, I would really like to see an actual depth (max 18", nominal 12") It doesn't need to be accurate within .001%, but accurate to 5-10% would be nice)
--
"When the hammer drops, the bullshit stops"



SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
reply to alphapointe

There is eTape »www.milonetech.com/Home_Page.html

OT what are you using for radio?


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

1 edit
reply to alphapointe

I agree eTape is most probably the best and simplest solution.

a) If you want something like etape, but want to stick it to outside surface of a glass/fiberglass/plastic container, there are capacitive tapes.

»www.molex.com/molex/products/fam···oduction

b) There are also radar-style RF sensors but a small antenna needs to be mounted to top inside surface of container. But won't measure accurately if liquid rises too close to the antenna.



alphapointe
Don't Touch Me
Premium,MVM
join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..
reply to SparkChaser

I'll do some reading on it when I get to work. The cooling tower is metal, so I'm not sure how well a capacitive sensor will work...

The radios I got are AP220 serial RF modules that I picked up off Ebay. They seem to work OK.
--
"When the hammer drops, the bullshit stops"


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

Sorry, was not following the thread for some time. Capacitive sensing won't work at all through metal and the radio may not work reliably.



alphapointe
Don't Touch Me
Premium,MVM
join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..

I'm not worried about the radio. It and the arduino will be mounted to the top of the tower inside a plastic weatherproof box with a SLA battery and solar cell, and cabled to the sensor below. The receiver will be about 70' away line of sight, so that shouldn't be a problem.
--
"When the hammer drops, the bullshit stops"



alphapointe
Don't Touch Me
Premium,MVM
join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..

I'm going with the Etape that SparkChaser See Profile linked to. Reading the datasheet, it looks like this is the best option. Now its' time to start writing and testing code on both sides of the link.

YAY!
--
"When the hammer drops, the bullshit stops"