Hi
I need to monitor water in fuel. I managed to source a sensor from a company in Italy called Sigmar. its mainly designed for Automobile and hence only comes in 12VDC connection.
How do I connect this sensor to my PLC running 24VDC. Is there a neat solution?
Thanks
Probably, yes.
Best regards, Spehro Pefhany
LOL.
Perhaps we might get a few more details. Could you possibly put a resistor in series with your sensor, equal to the resistance of your sensor?
Michael
Perhaps a link to detailed technical information on the modle of "Sigmar" sensor the OP has?
A quick search failed to turn up anything of use.
Best regards, Spehro Pefhany
LM7812 Voltage Regulator, 3 terminal
The output may also require level-shifting for the PLC to "understand" so simply providing it with 12VDC on input may not be enough.
no need to LOL.. that's why Most engineers are thought of as nerds with thick glasses.
Ofcourse i can put a resistor in series but it look like a high school project. And for those of you who work in the petrochemical industry, would this be acceptable?
Can i get a DIN rail mounted resistor?
Very small chance output from sensor would need any changing as most likely
0 to some voltage (1,5 or10) or maybe 4-20 ma if analog output. If a discrete then use a pulldown configuration with resistor back to 24V.Akheel and other posters need to supply more info on their posts, least give them something to look at and if nothing else will learn something :).
It seems that they make 12-24 V units!
Water Signal® is a patented resistive Water In Fuel (WIF) sensor that monitors and detects the presence of water in the fuel feed system of endothermic engines, and is particularly suitable for diesel engines. Sigmar's Water Signal® is vital to helping deliver clean, water-free fuel to your engine.
Sigmar's basics models consist of a single cylindrical housing that is screwed to the bottom of the fuel filter which permits the drainage of any water collected in the decantation bowl. This housing contains the electronics that both measure the electrical conductivity of the liquid contained in the bowl as well as amplify the water level detector's signal and power the warning lamp. Therefore there is no need for connection to an ECU on the part of the client.
The Water Signal® has the following electrical characteristics:
Protection:
The device can be connected to the rest of the circuitry by means of a
3-pole Fast-on connector of the client's choice.Sigmar can offer you a whole range of choices such as sensors with: any type of threading you may require, 12 or 24 Voltage, battery positive or negative, mono- or bi-electrode etc. Should you choose to use a mono-electrode sensor, care should be taken to ensure that the metal body of the filter is grounded.
Water Signal® automatically tests its own functioning. Whenever the ignition key is switched on, the indicator generates a two second AUTOTEST signal indicating that the device is operating normally. When water in the filter goes beyond the pre-determined safe level, the alarm is raised by means of a warning lamp and/or buzzer permitting water to be drained out of the system before it affects the engine.
The Water Signal® is available in different models that meet the different needs of every market. Sigmar is the world's leading WIF sensor designer and manufacturer. Should you require a model with a completely different housing design, a different function (e.g. capacitive rather than resistive), that features an integrated drain assembly, etc., Sigmar is easily able to create a WIF sensor that meets your specific needs. Sigmar is able to take a project form the earliest design phases through series producti
You really need to tell us a bit about the device. For a start, how may connections does it have? What kind of output does it have?
Walter.
Now *there* is a good approach to getting help. They are high-index-of-refraction, so rather thin, thank you.
You can get perf-board terminal assemblies that are DIN rail mounted.
I would think a bigger issue would be whether an automotive sensor would be acceptable in that industry, but that's not what you asked.
Looks to me like it has an open collector (NPN) output and should work directly with a PLC (the 12/24V type of sensor).
Best regards, Spehro Pefhany
Since the majority of large diesel gen sets use 24VDC starting circuits I (for one) would be surprised if it *wasn't* available in 24VDC.
From reading the above, this sounds like a useful little unit. Now if only I can find a use... ;-)
Cameron:-)
"Herman Family" wrote in news:RHyic.2430$ snipped-for-privacy@news02.roc.ny:
That really isn't the ideal approach. Might work if the sensor really has a stable impedance.
Guaranteed to work: Three terminal voltage regulator. Made for the purpose, and in the 3 dollar range. Try the LM317,
Scott,
I'd be more embarrassed if I were an electrical engineer. I think I'd go with your method.
Michael
Scott
You missed it earlier, LM7812, no programming resistors for these, 3 terminal FIXed voltage, LM78xx and LM79xx for negative. Can mount in a 3 terminal molex or amp connector and cover TO-220 with shrink or incapcilate assembly.
"mindspringnews" wrote in news:kCajc.3330$ snipped-for-privacy@newsread2.news.atl.earthlink.net:
Much better option. I just couldn't place the data sheet, so I didn't know what the max input voltage was.
Scott
Other mfg. still make too
If you are not worried about speed of response and assuming it is a digital sensor (ie either On or Off, no analogue output) you could use a relay with a
12v DC coil connected to your sensor's output, then connect +24v from the PLC to one side of the relay contact, the other side to the PLC input terminal (assuming it's a PNP input PLC I/O Expansion card).If speed of response is an issue use an opto-isolator.
JPG
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