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Selection criterias of CT PT to connect SENTRON PAC 3200

Created by: PISCEAN 2010 at: 7/8/2013 9:26 AM (6 Replies)

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7/8/2013 9:26 AM	Rate (0)
PISCEAN 2010 Diamond Member Joined: 4/23/2010 Last visit: 12/31/2023 Posts: 8092 Rating: (878)	Hello Experts, Which criterias are to be looked uponwhile selection ofCT & PT to be connected with SENTRON make PAC 3200 power monitoring device? Please find attached here with the sheet of accury values of PAC 3200 meters are specified. As per manual, these values depends upon CT & PT connected. So can any one help? Thanks in advance. DEEP. Attachment Sentron PAC 3200 PMD accuarcy value.pdf (599 Downloads)
	Last edited by: PISCEAN 2010 at: 7/8/2013 9:38 AM Attachement added
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7/8/2013 10:51 AM	Rate (0)
Ste39 Platinum Member Joined: 1/21/2013 Last visit: 10/23/2024 Posts: 4620 Rating: (708)	Hi DEEP, Have a look go to page 8: Instrument Transformer Basic Technical ... - GE Digital Energy

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7/8/2013 11:11 AM	Rate (0)
PISCEAN 2010 Diamond Member Joined: 4/23/2010 Last visit: 12/31/2023 Posts: 8092 Rating: (878)	Hello Ste39 , Thank you for beautiful article. I had searched on web also, but I get only technical articles. But it does not help me to select instruments so as to get optimum accuracy from above meter.

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7/8/2013 11:25 AM	Rate (0)
Valli Posts: 262 Rating: (45)	Hi, Well, when we say accuracy of measuring system, we should consider not only Meters's accuracy but also meteringCT's accuracy... So if PAC 3200 gives 0.5 class accuracy and backed up by class 1 CT then the over all accuracy of the system will not be 0.5 class. IfAccuracy of the Current Transformer – Class 0.5 and Accuracy of the PAC 3200 Meter – Class 0.5Then Accuracy of the system is Class 1Because,Accuracy of the CT: Class 0.5 means the measurement is 99.5% accurateAccuracy of the meter: Class 0.5 means the reading is 99.5% accurateSo the system is 0.995 X 0.995 = 99% accurate – that is Class 1 accuracy Hence, both the instrument transformer as well as the PAC 3200 meter should have a high accuracy class to get overall better accuracy of the system! The power consumption of PAC3200 @ CT input is 4 mVA at 1 A 115 mVA at 5 A per phase, and hence right/ any KVA better then this should be selected. FOR PAC 3200, PT is not required upto 690VoltAC, Cat III catagory, you can use only a 0.6A of fuse b/t Voltage tapping of mains and PAC V₁, V₂& V₃terminals.
Valli Posts: 262 Rating: (45)	Last edited by: Valli at: 7/8/2013 11:28 AM
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This contribution was helpful to 1 thankful Users Ste39

7/8/2013 11:30 AM	Rate (0)
Ste39 Platinum Member Joined: 1/21/2013 Last visit: 10/23/2024 Posts: 4620 Rating: (708)	Hi DEEP, In simple terms more than the class of the current transformer is low and more than accurate.

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7/8/2013 12:08 PM	Rate (0)
PISCEAN 2010 Diamond Member Joined: 4/23/2010 Last visit: 12/31/2023 Posts: 8092 Rating: (878)	Valli Hi, IfAccuracy of the Current Transformer – Class 0.5 and Accuracy of the PAC 3200 Meter – Class 0.5Then Accuracy of the system is Class 1Because,Accuracy of the CT: Class 0.5 means the measurement is 99.5% accurateAccuracy of the meter: Class 0.5 means the reading is 99.5% accurateSo the system is 0.995 X 0.995 = 99% accurate – that is Class 1 accuracy Hi, Assuming above as thrue, then how current accuracy> 99%, precisely 99.6%, can be achieved?(error limit as per specification is +/- 0,2%) In short I would like to ask, are there any CTs available having precise than 0,5?

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7/9/2013 6:13 AM	Rate (0)
Valli Posts: 262 Rating: (45)	Hi, If I refer to IEC 60044-1, we found the following precision classes for measuring CTs:-Classes 0.1, 0.2s, 0.2, 0.5, 0.5s, 1, and 3. Hence, we may need the current transformer with higher precisions - for PAC3200 +/- 0.5% and for PAC4200 +/- 0.2% to get the desired result like for 99.6A you may need a CT and PAC 4200 both with the 0.2% of accuracy. Attached is the catalogue extract of “4M Protective and Measuring Transformers” catalogue where-in you will find high precision CT’s detail i.e. 0.2 or so. You can also google it for the local SL representative to get more info on pricing/ availability etc. Application: most of the utility companies who charge for the electricity which they supply/ or we use they use 0.2 class CT with PAC 4200. Attachment Siemens_CT.pdf (590 Downloads)
Valli Posts: 262 Rating: (45)
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This contribution was helpful to 2 thankful Users PISCEAN 2010 sparten

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