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#197187 - 11/14/10 08:07 AM CT question  
sparkyinak  Offline
Joined: Jul 2007
Posts: 1,327
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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#197202 - 11/14/10 06:45 PM Re: CT question [Re: sparkyinak]  
LarryC  Offline
Joined: Jul 2004
Posts: 783
Winchester, NH, US
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.

#197207 - 11/14/10 09:16 PM Re: CT question [Re: LarryC]  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,857
Brick, NJ USA
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.


#197215 - 11/15/10 12:11 AM Re: CT question [Re: HotLine1]  
sparkyinak  Offline
Joined: Jul 2007
Posts: 1,327
It makes sense to me, but would degrade the accuracy is what I'm concern.

"Live Awesome!" - Kevin Carosa

#197216 - 11/15/10 01:20 AM Re: CT question [Re: sparkyinak]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,103
My guess is the manufacturer will not guarantee the accuracy if it is not installed exactly the way they say.

Greg Fretwell

#197225 - 11/15/10 10:07 AM Re: CT question [Re: gfretwell]  
resqcapt19  Offline
Joined: Nov 2000
Posts: 2,148
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.


#197234 - 11/15/10 02:54 PM Re: CT question [Re: resqcapt19]  
JBD  Offline
Joined: Jul 2001
Posts: 599
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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