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International Standards for Thermography of Bus Duct

04/28/2014 1:35 AM

can anyone tell me which international standard gives guidelines about thermography test of transformer bus duct. what should be the maximum allowable temperature in the bus bar / joints in the bus duct running from transformer to Main Low Tension panel.

i,m getting temperature of around 100 degree at the joint of bus duct

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#1

Re: International Standards for Thermography of Bust Duct

04/28/2014 11:15 AM

100 degrees Kelvin would be exceptionally low.

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#3
In reply to #1

Re: International Standards for Thermography of Bust Duct

04/28/2014 5:57 PM

Especially for large

...

tracts of land

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#8
In reply to #3

Re: International Standards for Thermography of Bust Duct

04/28/2014 11:37 PM

I know, but I want the-- the girl that I marry to have......a certain,... special... something!

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#11
In reply to #1

Re: International Standards for Thermography of Bust Duct

04/29/2014 10:09 AM

Now be nice.....

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Guru

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#2

Re: International Standards for Thermography of Bust Duct

04/28/2014 1:56 PM

Ask the manufacturer of the bus duct. They will be able to tell you what is the acceptable temperature limit for their product, based on all applicable standards. Also review their instruction manuals.

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#4

Re: International Standards for Thermography of Bus Duct

04/28/2014 9:53 PM

Engineers (IEEE)www.ieee.org

American National Standards Institute (ANSI) www.ansi.org

InterNational Electrical Testing Association (NETA)www.netaworld.org

National Fire Protection Association (NFPA)www.nfpa.org

National Electrical Code 2011 Edition (NFPA70)http://www.nfpa.org

Electrical Safety in the Workplace-2011 Edition (NFPA 70E)http://www.nfpa.org

ASTM Internationalwww.astm.org

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Guru

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#5

Re: International Standards for Thermography of Bus Duct

04/28/2014 10:38 PM

I'm going to assume that is 100°C, right?

Standards and manufacturer's stated operating conditions aside, that sounds very hot to me, and also it's a joint.....seems to have given you some pause to wonder as well.

How does the joint temperature differ to the bus temperature?

How much current are you pulling?

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Guru
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#6

Re: International Standards for Thermography of Bus Duct

04/28/2014 10:54 PM

What temperature does the bus bar show away from any joints? If the joints are much hotter than the bus bar itself, they may need tightening or other maintenance.

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#7

Re: International Standards for Thermography of Bus Duct

04/28/2014 11:30 PM

Thermograph temperatures are usually in degrees C above ambient. I would be concerned at a joint temperature of 100 deg above the rest of the bus. Schedule a shutdown asap and check it out. Beware that the elevated temperature may be due to a source of heat within the transformer.

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#9

Re: International Standards for Thermography of Bus Duct

04/28/2014 11:46 PM

Generally the busducts are designed for a temperature rise of 35 deg C over an ambient temperature of 50 deg C. This means final temperature should not be greater than 85 deg C. This final temperature is decided based on the insulators' characters. There are IEC / IS standards for this . However there is no relevant standards for thermography study on Busducts.

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#13
In reply to #9

Re: International Standards for Thermography of Bus Duct

04/30/2014 12:20 AM

Pappey......50C is IS

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#14
In reply to #13

Re: International Standards for Thermography of Bus Duct

04/30/2014 12:28 AM

I do not understand your comment. Can you elaborate.

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#10

Re: International Standards for Thermography of Bus Duct

04/29/2014 4:18 AM

Assuming it's to an IEC standard (61439-6) then the limit would be 105K rise over 35C ambient as a maximum. But remember that limit is with the unit running at 100% current. I would check other joint to gauge if this one is high or they are all similar

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#12

Re: International Standards for Thermography of Bus Duct

04/29/2014 11:03 AM

I did a lot of infrared testing of all sorts of equipment. In general, the joints should not be much higher than the main part of the bus. In old bus ducts the heating may be caused by deterioration of the joint area by contamination or over tightening. Rarely by under-tightening. We actually had a team out of New York, who would travel the country rebuilding bus ducts. They could do it faster than it could be replaced. They would replace insulation, straighten the contact areas, silver plate, etc. The cost was 85% of new, but the time savings attracted many customers. Contrary to a comment earlier, tightening rarely improves the connection. The connection pressure usually is controlled by Belville washers and if you overtighten, the bus bar is distorted and point contact results and heating increases. Manufacturers torque values should not be exceeded!

The temperature depends on the type of insulation and there is no general rules for which standard it meets without manufacturing data or more knowledge of insulation to be able to recognize it, but as a general rule, I would not expect the joint to be more than 10 or maybe a max of 15 C above the main part of the bus duct. Most of the time it is just about the same temperature.

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