Capacitance Probe

7 comments

resh_cop11 Active Contributor Join Date: Jun 2011 Posts: 20	Capacitance Probe 03/27/2012 6:24 AM
	Hey everybody, we using level transmitter type is capacitance probe.. Endress houser. We facing a problem. We communicate with hart portocol. Check capacitance value.. Showing 70.1pF. Now actual level is 100%... So im did span adjustment for 100%. When level going down... Level not moving. The capacitance value still in the same value.. How to make sure the transmitter in a good condition?
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: Capacitance probe 03/27/2012 6:40 AM
	What is the capacitance when the liquid is no longer in contact with the probe? For example, if it is still 70.1pF, then there is no fault with the transmitter. Please elaborate with more information. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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resh_cop11 Active Contributor Join Date: Jun 2011 Posts: 20	#3 In reply to #1 Re: Capacitance probe 03/27/2012 9:10 AM
	1stly m take it out from field and communicate with hart. check the capacitance value at hart found 71.1pF..then fixback at field.. Actual level is 100percent. but leveltransmitter still in a 0%. check the capacitance value still in a same value 70.1pF. any idea to trouble shoot?
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#7 In reply to #3 Re: Capacitance probe 03/28/2012 3:19 AM
	See #6↓. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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Iris Guru Join Date: Jul 2010 Posts: 669 Good Answers: 176	#2 Re: Capacitance Probe 03/27/2012 9:07 AM
	Which model number probe/transmitter? What is the tank material? Steel? plastic? What is the medium in the tank? Is this a new installation, or has the unit worked previously and now it does not?
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resh_cop11 Active Contributor Join Date: Jun 2011 Posts: 20	#4 In reply to #2 Re: Capacitance Probe 03/27/2012 9:14 AM
	E&H.. USING FOR COOLING TOWER. MATERIAL WATER..
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Iris Guru Join Date: Jul 2010 Posts: 669 Good Answers: 176	#5 In reply to #4 Re: Capacitance Probe 03/27/2012 10:43 AM
	My questions are specific. Except for your answer "water" as a medium, your answers are not. Your grade on my test is F for failing.
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#6 In reply to #4 Re: Capacitance Probe 03/28/2012 3:19 AM
	As the composition of cooling tower water, its temperature and therefore its dielectric constant varies, capacitance is not the correct measuring technique for this application. Choose something else, for capacitance won't work reliably. Ultrasonic should be near the top of the list for possibilities. Please don't SHOUT. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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Iris (2); PWSlack (3); resh_cop11 (2)

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