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CT question #197187 11/14/10 07:07 AM
Joined: Jul 2007
Posts: 1,335
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sparkyinak Offline OP
Member
Providing a CT has the amperage output, can a single CT provide accurate signalling to two or more meters requiring a CT?


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Re: CT question [Re: sparkyinak] #197202 11/14/10 05:45 PM
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LarryC Offline
Member
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.

Re: CT question [Re: LarryC] #197207 11/14/10 08:16 PM
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Posts: 7,218
HotLine1 Offline
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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
Re: CT question [Re: HotLine1] #197215 11/14/10 11:11 PM
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sparkyinak Offline OP
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It makes sense to me, but would degrade the accuracy is what I'm concern.


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Re: CT question [Re: sparkyinak] #197216 11/15/10 12:20 AM
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gfretwell Offline
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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
Re: CT question [Re: gfretwell] #197225 11/15/10 09:07 AM
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resqcapt19 Offline
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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)
Re: CT question [Re: resqcapt19] #197234 11/15/10 01:54 PM
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Posts: 599
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JBD Offline
Member
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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