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CT question
#197187
11/14/10 08:07 AM
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Joined: Jul 2007
Posts: 1,335
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Providing a CT has the amperage output, can a single CT provide accurate signalling to two or more meters requiring a CT?
"Live Awesome!" - Kevin Carosa
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Re: CT question
[Re: sparkyinak]
#197202
11/14/10 06:45 PM
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Joined: Jul 2004
Posts: 783
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I will take a wild guess, but if the two meters are physically close AND you connect the two meter's CT inputs in SERIES, I think yes. Acceptable practice, I do not know.
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Re: CT question
[Re: LarryC]
#197207
11/14/10 09:16 PM
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Joined: Apr 2002
Posts: 7,237
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Another wild guess of 'yes'. Pondering a little deeper, I would venture a guess that as long as the 'meter' device doesn't exceed the power (correct term?) output of the CT, multiple 'meters' could be attached.
John
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Re: CT question
[Re: HotLine1]
#197215
11/15/10 12:11 AM
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Joined: Jul 2007
Posts: 1,335
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It makes sense to me, but would degrade the accuracy is what I'm concern.
"Live Awesome!" - Kevin Carosa
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Re: CT question
[Re: sparkyinak]
#197216
11/15/10 01:20 AM
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Joined: Jul 2004
Posts: 9,577
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My guess is the manufacturer will not guarantee the accuracy if it is not installed exactly the way they say.
Greg Fretwell
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Re: CT question
[Re: gfretwell]
#197225
11/15/10 10:07 AM
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Joined: Nov 2000
Posts: 2,148
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CTs have a rated maximum current output and a maximum circuit resistance. As long as the load of the multiple meters is below the maximum permitted load, there will be no issues with the operation or accuracy. http://www.nktechnologies.com/pdfs/ct-tutorial.pdf
Don(resqcapt19)
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Re: CT question
[Re: resqcapt19]
#197234
11/15/10 02:54 PM
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Joined: Jul 2001
Posts: 599
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In the days of electromechanical meters it was standard practice to provide a single set of CT's to feed both the Ammeter and the Wattmeter. Even in today's world of electronic meters it is still common.
However, it is rare that a protective device and a meter will share a single set of CT's (although it seems common in MV starter applications).
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