ECN Forum Forums General Topics of the Trade General Discussion Area CT question

Providing a CT has the amperage output, can a single CT provide accurate signalling to two or more meters requiring a CT?

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.

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.

It makes sense to me, but would degrade the accuracy is what I'm concern.

My guess is the manufacturer will not guarantee the accuracy if it is not installed exactly the way they say.

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

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).