You Just Gotta Tighten Those Connections! - Electrician Talk - Professional Electrical Contractors Forum

brian john · 03-19-2007, 04:49 PM

While it is hard to see the hardware for this CT, it was loose, never tightened. check the temperature of the spot, the hottest spot (not in this text was 266.6 F) The picture has been edited to remove the customer information. The black marks are magic marker and is utilized to obtain the temperature without the copper emistivity effecting the reading.

MDShunk · 03-19-2007, 04:54 PM

Quote:

Originally Posted by brian john

The black marks are magic marker and is utilized to obtain the temperature without the copper emistivity effecting the reading.

Can you talk a little more about that? That is, what is copper emmisivity, and how does it affect the reading if you don't scribble black marker on the buss tang?

brian john · 03-19-2007, 06:01 PM

Marc:

I am not an IR thermographer and have limited knowledge on this subject, but basically it has to do with reflection of the surface which can skew the temperature. If I use the camera and look an a galvanized can I can see my image in the IR camera even though with a real time camera or my eye nothing is visible. Every substance (I believe) has an emissivity number.

From IEEE Dictionary:

Emissivity - The ratio of power radiated by a substance to the power radiated by a blackbody at the same temperature.

rod213 · 03-19-2007, 06:04 PM

Ah, I get it I think. You mark on it first with your marker so it doesn't reflect and you get a true temp reading with your IR? Otherwise itwould look like the rest of the area on that buss without the sharpie.

Interesting stuff there.

MDShunk · 03-19-2007, 06:50 PM

Is this a special di-electric marker? Or an ordinary one from the office supply store? You don't have to answer that if it's a trouble making question. I was just wondering.

brian john · 03-19-2007, 08:14 PM

Marc:

I'd rather not know...But yes it is a regular marker and I have warned him before..........But Steve says he has to do it to get a clear real picture. NOW PLEASE DO NOT REPEAT THIS it is strictly between you me and the rest...

I should have figured you'd pick up on this.

InControl · 03-20-2007, 03:18 PM

We have yearly IR scans at the plant where I work. I've never heard of the black magic marker thing. I would think that it would give false high readings because the black would absorb heat.

brian john · 03-20-2007, 04:48 PM

Just the opposite, it minimizes the reflection.

Are your thermographers Certified and electricians? Many thermographers are not electricians and while heat is heat have NOT A CLUE regarding electrical issues. Ie why there are thermal issues with a particular piece of equipment, Induction, bolted pressure switch issues...ECT.

Quote:

The ratio of power radiated by a substance to the power radiated by a blackbody at the same temperature

InControl · 03-20-2007, 05:02 PM

We used to outsource our IR scans but our company is big enough that we had one of our electricians get sent out to get certified and the whole nine yards. I'll have to pick his brain when I get back to work.