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Monitoring KWH usage #8604 03/29/02 07:27 PM
Joined: Mar 2002
Posts: 6
C
Chris Paul Offline OP
Junior Member
Hello everyone,
I was wondering if anyone had any idea on where I can get a CT for a 3000 amp service. I'm trying to monitor the KWH consumption for my facility and the largest CT I can find is a 2000 amp. Maybe if no one knows of any CTs that big they can give me some info on how I might accomplish my goal. These pulse inputs are going back to a monitoring device called a gateway which can be accessed anywhere through a modem. Thanks for any help.
Chris

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Re: Monitoring KWH usage #8605 03/29/02 10:04 PM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline
Member
Could you monitor one of a parallel group and have your software multiply the results by the number of conductors?
(Forgive my ignorance)

Re: Monitoring KWH usage #8606 04/01/02 10:39 AM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
Check out a company called Flex-Core at http://www.flex-core.com. They make all sorts of different CTs, including split core styles for mounting on existing cables.

Square D also lists window style units up to 6000:5 ratios and split cores to 5000:5

Re: Monitoring KWH usage #8607 04/02/02 11:15 AM
Joined: Apr 2002
Posts: 3
B
bgautreau Offline
Junior Member
Chris,

Most CT's will have a "rating factor" (RF). For instance, if the CT was a 2000 amp unit with an RF of 2, then the thermal capability would be 4000 amps.

Because of this, it is not always necessary to "match" the CT size to the service size.

Feel free to email me if you have more questions.

Bob

Re: Monitoring KWH usage #8608 04/03/02 11:37 AM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
While bgautreau is technically correct concerning "rating factor", you must still take into account your transformer ratio.

In your case a 2000:5 CT is a 400 to 1 ratio, so when it is used on a 4000A service it will provide an output of 10A. Your measuring equipment may not be able to deal with this large of a value.

The rating factor should only be used to allow for momentary overcurrents (i.e. motor start-up)which do not need to be be measured accurately

Re: Monitoring KWH usage #8609 04/03/02 09:26 PM
Joined: Apr 2002
Posts: 7,211
HotLine1 Online Content
Member
Try National Meter Industries www.national-meter.com
or 1-800-325-6674
They have any ct's and are very helpful

John


John
Re: Monitoring KWH usage #8610 04/03/02 09:42 PM
Joined: Oct 2000
Posts: 3,961
Bill Addiss Offline
Member
Chris,

You can ask the "Meter Guy"
at: http://www.themeterguy.com/splash.htm

Bill


Bill
Re: Monitoring KWH usage #8611 04/15/02 12:09 AM
Joined: Apr 2002
Posts: 2,527
B
Bjarney Offline
Moderator
They're around but the freight might be stiff.
http://www.geindustrial.com/cwc/products?pnlid=5&id=insttran

Assuming window CTs with big enough windows, how about a pair of 1500:5 units in series?


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