Daisy Chained CT's
Daisy Chained CT's
(OP)
Hello,
Researching what effect piggybacking another CT onto an existing CT might have. We have 300:5 CT's for 12.47KV 3MW generators that we'd like to tap onto with an analyzer's CT's. I'd like to learn how much of an effect the analyzer's CT's would have on the signal out of the 300:5's. Any input is appreciated.
Thanks
Researching what effect piggybacking another CT onto an existing CT might have. We have 300:5 CT's for 12.47KV 3MW generators that we'd like to tap onto with an analyzer's CT's. I'd like to learn how much of an effect the analyzer's CT's would have on the signal out of the 300:5's. Any input is appreciated.
Thanks






RE: Daisy Chained CT's
RE: Daisy Chained CT's
RE: Daisy Chained CT's
RE: Daisy Chained CT's
Let me ask without using the terms primary and secondary:
Are you putting your analyzer CT around one of the two 0-5A leads from the existing CT, or are you putting your analyzer CT around the large single conductor whose current is being measured by the existing CT?
Best to you,
Goober Dave
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RE: Daisy Chained CT's
stevenal, you caught me. They are transducers similar to these:
newark
tequipment
So they probably just measure potential across a known resistance, correct? Are your opinions that the impedance the "main" ct loop would see is negligible and we shouldn't have to calibrate any of our meters that use the main CT?
RE: Daisy Chained CT's
Those are current clamps. You can put them around the "heavy conductor". No sweat. We do it all the time and do not influence primary current at all. At least not to the extent that we worry about it. And probably less than a tenth of other error sources - i.e. not at all.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Daisy Chained CT's
RE: Daisy Chained CT's
Sounds like there shouldn't be much impedance from tapping a 0-5A DC out CT on the main CT's secondary loop. We can try one and see how it goes.
Thanks for all the help!
RE: Daisy Chained CT's
RE: Daisy Chained CT's
RE: Daisy Chained CT's
RE: Daisy Chained CT's
And, again, our analyzer needs a dc voltage output like the probes I linked to above. We would chose a 1:1 0-5A probe to measure the current on the secondary of the main CT. Or do you see a problem with this? If there's something out there we don't have to make ourselves that we could put in series of the main CT's secondary loop and convert to DCV out, I'm guessing that might be more accurate. But my main question is still a little uncertain: what sort of magnitude change would we expect from the added impedance to that main CT loop (either option). Sounds like no one here has run into any significant problem before. We'll probably see if we can dig up some vendor numbers and just crunch, and then do a test setup on one of the generators.
Also, I promise to try and use another term besides "tap" in future posts :)