Incorrect CT Ration

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markthg Participant Join Date: Mar 2014 Posts: 2	Incorrect CT Ration 03/26/2014 11:24 AM
	Hi, We have come across a meter in a building we are working on that has the incorrect CT ratio programmed in to it. The meter is set up for 100/5 CT, however the actual CT installed are 600/5. We can reprogram the meter so that going forward data is correct, however what calculation would i need to use on the historical data to correct for the incorrect ratio? Thanks.
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RAMConsult Guru Join Date: May 2007 Location: NYC metropolitan area. Posts: 3230 Good Answers: 444	#1 Re: Incorrect CT Ration 03/26/2014 11:32 AM
	Multiply by 6. __________________ “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
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markthg Participant Join Date: Mar 2014 Posts: 2	#2 Re: Incorrect CT Ration 03/26/2014 1:31 PM
	Thanks. I wasn't sure if it was going to be as straight forward as that or not.
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RAMConsult Guru Join Date: May 2007 Location: NYC metropolitan area. Posts: 3230 Good Answers: 444	#3 Re: Incorrect CT Ration 03/26/2014 1:56 PM
	Here's why. Assume that 600 Amps was passing through the CT, it then reported 5 Amps to the meter which used your setting, 100A, as the amount of current to use in its calculations; therefore the charges were off by a factor of 6. It might be a good idea to put a tamper-proof seal and lock on the meter enclosure, just in case it was no accident. __________________ “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
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Just an Engineer Guru Join Date: Feb 2008 Location: Australia Posts: 2181 Good Answers: 255	#4 Re: Incorrect CT Ration 03/26/2014 4:55 PM
	We had same happen for new pumpstation. We asked the supply authority to check the CTs after our first bill was only 25% of expected. They assured us "Everything OK". We asked them again two months later. They assured us "Everything OK." We asked them again 1 year after opening. They assured us "Everything OK." We stopped asking. At two years into project, they realised something was wrong, came and checked CT's and "discovered" the error. Now trying to back bill us. Pumpstation has 3 x 600kW, 2 x 1200kW and 2 x 400kW pump sets, each running 4hrs per day (minimum). The bill is significant. What was interesting is that all three phases were wrong, but our own CT's in the same cabinet for process and load monitoring were correct. __________________ Just an Engineer from the land down under.
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pnaban Guru Join Date: Jun 2010 Location: srilanka Posts: 2725 Good Answers: 5	#5 In reply to #4 Re: Incorrect CT Ration 03/26/2014 10:41 PM
	Show them the kwh,kW readings in your meters & ask them to pay compensation __________________ pnaban
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Wal Guru Join Date: Jun 2011 Location: Phnom Penh Posts: 4019 Good Answers: 102	#6 In reply to #4 Re: Incorrect CT Ration 03/26/2014 11:13 PM
	You are in Oz right? Getting a bill for an adjustment after two years of everything being declared Ok and especially after honest prompting by the customer sounds like something you want to take up with Consumer Affairs. You may not only just not have to pay you may even get compensated for being dikked about with. __________________ Difficulty is not an obstacle it is merely an attribute.
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Just an Engineer Guru Join Date: Feb 2008 Location: Australia Posts: 2181 Good Answers: 255	#7 In reply to #6 Re: Incorrect CT Ration 03/27/2014 4:24 PM
	It's OK. Our legal boys are on top of it. The supplier is following it up since it is $M, but we are pretty certain they will not follow to court. __________________ Just an Engineer from the land down under.
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Wal Guru Join Date: Jun 2011 Location: Phnom Penh Posts: 4019 Good Answers: 102	#10 In reply to #7 Re: Incorrect CT Ration 04/08/2014 12:33 AM
	How are the boys in Legal getting on with this? __________________ Difficulty is not an obstacle it is merely an attribute.
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Anonymous Poster #1	#8 Re: Incorrect CT Ration 03/27/2014 11:57 PM
	Happy Meals are incorrect rations for CTs.
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navdeep_goyal Associate Join Date: Apr 2014 Posts: 51	#9 Re: Incorrect CT Ration 04/07/2014 11:39 PM
	As your meter is programmed for 100/5 so your meter may be running very fast as compared when its is programmed at 600/5 so your power consumption data will be six times more when programmed at 100/5 instead of 600/5 so divide energy meter reading by 6 to get correct data
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Anonymous Poster (1); Just an Engineer (2); markthg (1); navdeep_goyal (1); pnaban (1); RAMConsult (2); Wal (2)

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