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CT question #197187
11/14/10 08:07 AM
11/14/10 08:07 AM
S
sparkyinak  Offline OP
Member
Joined: Jul 2007
Posts: 1,335
Alaska
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
Work Gear for Electricians and the Trades
Re: CT question [Re: sparkyinak] #197202
11/14/10 06:45 PM
11/14/10 06:45 PM
L
LarryC  Offline
Member
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.

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

Member
Joined: Apr 2002
Posts: 6,997
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.


John
Re: CT question [Re: HotLine1] #197215
11/15/10 12:11 AM
11/15/10 12:11 AM
S
sparkyinak  Offline OP
Member
Joined: Jul 2007
Posts: 1,335
Alaska
It makes sense to me, but would degrade the accuracy is what I'm concern.


"Live Awesome!" - Kevin Carosa
Re: CT question [Re: sparkyinak] #197216
11/15/10 01:20 AM
11/15/10 01:20 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,253
Estero,Fl,usa
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 10:07 AM
11/15/10 10:07 AM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
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 02:54 PM
11/15/10 02:54 PM
J
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
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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