capacitive level sensor measuring problem
capacitive level sensor measuring problem
(OP)
We are using a single probe capacitive sensor to measure the level of a grain. The grain is filled in a box which is installed on a machine. When the machine is running for a while we make the calibrations and there is no problem. But when the machine stops for a while and then restarts the sensor does not measures the level correctly for a while and as time passes it measures correctly again. I'm suspicous of the earth. They try to reorganize the earth connection but no change. When the machine(s) first start there is zero potential difference between the earth and neutral. As time passes it grows up and reaches to 2Vs. I don't know if it's the reason but the change in the sensor follows the change of the potential difference between the earth and neutral. But we did not observe the same issue in another place even the difference changes more than that. What may be the problem? What should we care of? What do you suggest?





RE: capacitive level sensor measuring problem
As for the 2V.. Can you tell us more about the machine? Got a picture?
Keith Cress
kcress - http://www.flaminsystems.com
RE: capacitive level sensor measuring problem
Here is the picture
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sensor is on the upper part of the machine inside of the box.
RE: capacitive level sensor measuring problem
Is this a continuous level, or a level switch?
I've used Drexelbrook RF (capacitance) level devices for areas where product buildup or static was an issue. They have worked well for me.
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RE: capacitive level sensor measuring problem
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RE: capacitive level sensor measuring problem
RE: capacitive level sensor measuring problem
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RE: capacitive level sensor measuring problem
abfer; If you have a capacitance based sensor it is looking at congregated charge. A hopper full of 3kV grain could easily effect that sensor in various ways.
Does the grain fall down a shoot(sp?) to the machine? If it does you could try a few things to test the theory. One would be a very fine water mist being injected. Like steam fine. Or even a humidifier's output. There are some ornamental ones that put out an ultrasonically created water smoke. Alternatively there are static reduction fans you can buy off the shelf. They blow electrically charged air. We had to use them all over a leather tannery to kill the charge created by leather sliding across certain plastics. You could even try damp grain. I offer these suggestion only as a hypothesis test so you could prove what the issue is.
Keith Cress
kcress - http://www.flaminsystems.com
RE: capacitive level sensor measuring problem
RE: capacitive level sensor measuring problem
RE: capacitive level sensor measuring problem
Regards
Roy
RE: capacitive level sensor measuring problem
RE: capacitive level sensor measuring problem
Keith Cress
kcress - http://www.flaminsystems.com
RE: capacitive level sensor measuring problem
RE: capacitive level sensor measuring problem
Keith Cress
kcress - http://www.flaminsystems.com