Cheap & dirty sump Control 3

[tulum]

Anyone have a cheap solution to run a 15HP sump...

There is a 4-20mA signal availble to use for water level.

I just want to empty the hole when it gets full.

I was hoping there would be a relay that accepts 4-20mA and has a set of dry contacts.... If not could I put a resistor in and try to use the relays drop out/pick up voltage for the job?

Everyone here is talking about a small PLC but I think this is a waste of time...

Regards,
TULUM

 

[SteveMeisel]

Nothing is cheap. I have yet to see a Big-Lots flier with industrial supplies in it.

You could use a Newport meter with mA inputs and a relay contact or two. Set the limits to cut in the relay contacts at 4mA and out a 20mA. Done.

Steve

 

[richs]

Hiya-

You might be able to do it with a tiny bit of thought and
something called a "latching" relay. This device is
"set" when you have the full limit switch activated. The
latch is "reset" when the empty condition is met.

I would suggest NOT going with a 4-20ma loop. Go with
simple dry contact level switches. Otherwise you get into
the area of voltage comparators, etc.

The set and reset were quoted as one can make a SR flip
flop (a very common type of electronic circuit). The
SR stands for, you guessed it, set/reset.....

Now, I would strongly suggest that you drive the sump pump
from a rather heavy duty activator/contactor and drive
the contactor with the latching relay. 15hp definitely is
in the range of rather heavy duty contacts. You might
take a look at an electric elevator catalog or supply
house for the components (other than the level switches)
for your efforts.

Hope that this helps.

Cheers,

Rich S.

 

[itsmoked]

I do not know about Steve's suggestion. If it's workable it certainly sounds like the best solution to me! It would also provide remote level indication - undeniably useful.

I agree with Rich do not try to make a 4-20ma signal run any relay(directly) you will be sorry. Besides not working you may destroy the motor or the contactor.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[dpc]

Maybe something like this:

http://www.actionio.com/products/slimpak2/wv108.html

 

[ScottyUK]

I've successfully used one of these cheap & cheerful sensing relays for a septic tank pump controller. The electrodes were lengths of copper heating pipe - cheap to buy and replace, and reasonable corrosion resistance. Proper electrodes are available too, but this was a guvvy job for a Scout campsite, so cheap and field-maintainable was a priority.

http://omron-industrial.com/en/home...ringProdu/ConductiveLevel/61FGPN8/default.asp

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I don't suffer from insanity. I enjoy it...

 

[jraef]

I've used those Action Pak relays in dpc's link many times. Very very simple, inexpensive and reliable. 4-20mA in, pots on top to set the setpoint and adjust the deadband, relay output. Run the relay to the motor starter coil. Done.

http:/

http://www.jraef.com

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[DASKAT]

How about an Allen bradley Pico controller cheap and you can use it to set alarms or or indicators. less than 200 bucks.

 

[bigbillnky]

tulum
Goodafternoon,
The cheapest and easiest way is to use 2 fixed limit switches, a float ball mounted on a stem, and a ATL starter. The bottom limit switch closes when the float ball raises up due to an increase in level and provides power to the common side of both the top limit and the seal-in contact on the starter(the top limit and the seal-in contact are in parallel). The top limit will be closed by the float at the level you choose to start the pump and this in turn acts to seal-in the starter coil. The starter remains pulled in until the level drops low enough for the float to open the contacts of the bottom limit switch.

Bigbillnky,C.E.F.....(Chief Electrical Flunky)

 

[OperaHouse]

Another solution would be to use a current sense relay that turns on at a preset current. This would trigger an off delay timer. A fixed pit size would have a set time to empty it down to a certain level. This would cycle a few more times than pumping down to a fixed level.

 

[tulum]

Thanks for the help guys...

The situation is that there is already a 4-20mA water level signal there... so I think I will look at the Action instruments as well as the Omron suggestions above...

I have also find a Zelio controller for less than $200can and it does indicating and everything..

See what everyone thinks....

Thanks again...

 

[ScottyUK]

As you already have a mA signal, a couple of threshold relays may be the easiest solution to provide a start signal and stop signal to your pump starter. There's probably little difference in the cost of the hardware compared with a level sensing relay, but might save you some costs in the installation.

http://ecatalog.squared.com/catalog/173/html/sections/21/17321028.html#1014305

And here's another level control relay:

http://ecatalog.squared.com/catalog/173/html/sections/21/17321033.html#1015347

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I don't suffer from insanity. I enjoy it...

 

[tulum]

Good stuff Scotty....thanks..

TULUM

 

[bmsg]

A lot of people have already replied, and you may have decided what to do.
Alarm cards are available - which take in 4-20mA DC signal - and generate dry-contacts corresponding to user-selectable values. You can use one such card to generate two contacts - one when the sump is, say, 20% full (i.e., around 7mADC) and another when thesump is, say, 85% full (i.e., about 18 mA DC). This will do your job.
I cannot remember an international manufacturer off-hand - except for Yokogawa (which is relatively expensive in India, where I live.

 

[LionelHutz]

A Zelio is a decent solution. Unless something has changed you can only get a 24VDC supply, analog voltage input version so just use a 500ohm, 1/2 watt resistor to convert the current to voltage. Then, set up your levels and run it. The best part is that you can also program in some other controls (such as hand/auto) or level light outputs or low/high warnings at the same time.