Distance One Can Use for 4-20 mA Source

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kailash Active Contributor Join Date: Jul 2010 Posts: 12	Distance One Can Use for 4-20 mA Source 07/08/2010 12:50 PM
	i want to carry 4-20ma signal around 75 meters to the PLC input i plan to use 1.5 mm2 shelded cable is it will work ok ? i want to conform as other case i will loose the money for cable.
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#2 "Re: Distance One Can Use for 4-20 mA Source" by PWSlack on 07/08/2010 1:33 PM (score 2)

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#1 "Re: distance one can use for 4-20 ma source" by RDGRNR on 07/08/2010 1:08 PM (score 1)

RDGRNR Guru Join Date: Dec 2009 Location: San Antonio, TX USA Posts: 844 Good Answers: 29	#1 Re: distance one can use for 4-20 ma source 07/08/2010 1:08 PM
	The answer is probably yes, but you could have been a little more specific regarding the transmitter type, PLC type, process---Gees---ANYTHING! __________________ "Do not worry about your difficulties in Mathematics. I can assure you mine are still greater". - Albert Einstein
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kailash Active Contributor Join Date: Jul 2010 Posts: 12	#3 In reply to #1 Re: distance one can use for 4-20 ma source 07/09/2010 11:09 AM
	Dears thanks for the fastest and strong teachnical backround help provided i am really feel happy seeing such a strong talents i am using 5v to 4-20ma tranducer as i am going to mesure 1500A through Ct and send feed back to S7200 ( 224Xp) AI feedback in manual of S7200 it stated internal resistence used 250 ohms so as support provided it must work
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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	#2 Re: Distance One Can Use for 4-20 mA Source 07/08/2010 1:33 PM
	It depends upon the overall loop resistance, including the input resistance, and the supply voltage. Example: If the Loop voltage is, oh, say 24.0VDC then the maximum loop resistance is 24VDC/20mA which is......<tap, tap, tap>.....er.....1200Ω. The 1.5mm2 cable 75m long will have a there-and-back resistance of, oh, say a maximum of 5-10Ω, so that means if the PLC input resistance is below 1190Ω then everything will be just fine. Many PLC alnalog inputs will be rather less than this. And if it isn't, then just turn the supply volts up until it is. __________________ "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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Anonymous Poster	#4 In reply to #2 Re: Distance One Can Use for 4-20 mA Source 07/10/2010 12:33 PM
	I agree with your calculations.Most plc's designed for 4-20 milliamp inputs also have 250 ohm input resistance, to conform with the 4-20 milliamp, 1-5 volt standards. GA for you.
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Fareed1974 Member Join Date: Oct 2010 Posts: 6 Good Answers: 1	#5 Re: Distance One Can Use for 4-20 mA Source 10/30/2010 11:18 AM
	Yes it will go till 1000 meters
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#2 "Re: Distance One Can Use for 4-20 mA Source" by PWSlack on 07/08/2010 1:33 PM (score 2)

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#1 "Re: distance one can use for 4-20 ma source" by RDGRNR on 07/08/2010 1:08 PM (score 1)

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Users who posted comments:

Anonymous Poster (1); Fareed1974 (1); kailash (1); PWSlack (1); RDGRNR (1)

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