Busway Thermal Scan

[farmaped]

What is the M.O. for thermal scanning / inspection of energized 480V Busway (AKA Bus Duct) with plug in units. Manufacturer and NEMA literature are very specific concerning thermal scans "while energized under full load" .... makes sense.
Then, concerning plug-in unit inspection, the same literature is very specific to "ensure the unit is "OFF" prior to opening for inspection".
Does thermal scanning this equipment with all the inspection plates and plug-in unit doors' closed provide any benefit? Will it only pick up extreme "hot-spots".
I'm not nit-picking, I am just trying to put together a sensible busway PM program. Perhaps gross-faults would show up during a thermal scan with everything buttoned up. What is the "industry norm"?
Thanks

 

[ken44]

I realize that my response may not answer your question directly but I hope it will be helpful. Our Thermography Crew has only been operating for about 1 1/2 years and I was part of it for the first 3 months but then accepted another position within the agency, therefore I have some limited knowledge of the way they have been trained to do things. We use a cameral made by Square D and it has corresponding computer software and cost about 25K and it took the Thermography Crew a minimum of two days formal training plus weeks of trial and error out in the field to acheive what I call Level One Certificatioin, in order to acheive Level Two, its another week of formal training. I may be able to connect you with the Thermography Crew Leader via email and he may be able to answer your question, if you are interested, send me your email address and I will forward it to him along with your posting.

 

[76nemo]

To answer your question about scanning with "everything buttoned up", the answer is No. Thermal scanning looks at surface temperatures, it's not like x-ray vision. The system and all of it's components must be exposed for proper reading.

 

[charlietuna]

We open all bus disconnects and scan the terminations and bus fingers. The duct itself and the joints are scanned and problems can be seen on the surface of the duct. This requires extreamly sensitive camera equipment capable of seeing only a few degrees of temp. rise on a joint and a qualified camera operator. You should see the looks on a building manager's face when you explain he has a problem inside a bus joint when it looks brand new and he can't tell the difference in temp. with his hand!!!! And he's looking at maybe a $30k repair job???

 

[mxslick]

You should see the looks on a building manager's face when you explain he has a problem inside a bus joint when it looks brand new and he can't tell the difference in temp. with his hand!!!! And he's looking at maybe a $30k repair job???

Just casually drop the figure to replace that bus duct AFTER it fails violently and shuts down his building for several days...bet that $30k is suddenly dirt cheap!!

 

[cornbread]

You might want to look at IR scan windows. We installed a few here and they work great. No need remove covers or open doors.

 

[brian john]

You might want to look at IR scan windows. We installed a few here and they work great. No need remove covers or open doors.

A load of a minimum of 40% is best for scanning busway.
Busway joints can be scanned with some luck if you know what you are doing comparing joints to other joints in the busway run.
Scanning fusible disconnects or CB's, well they have to be open and this requires SAFETY.
The back of the busway buckets can be scanned if load is sufficient but as with busway joints take some comparison readings.

There are many factors involved such as a joint that is hot, but not completely burnt, IR will minimize chances of a blow up.

A straight visual inspection as you scan is important, looking for lose busway connection bolts, We see the Square D snap off bolts many times with the yellow tag intact. So there are advantages to completing IR I gurantee doing a visual I will always find issues of concern including thermal issues, NEC violations and mechanical issues.


SAFETY is a MUST in all electrical work, never take chances.

 

[farmaped]

Thanks for the good info. It appears that a thermal scan of the enclosed busway can be beneficial with a skilled technician and sensitive equipment. That was my main question, if there is no benefit to this I wouldn't prescribe it.
Additionaly, a de-energized visual inspection would be beneficial (but take an inordinate amount of time to complete).

As for the plug-in units, a proper thermal scan dictates the doors must be open, operating under load, and wear of PPE. It's just ironic the manufacturer's literature (at least the manufacturer we have) recomends a thermal inspection under full load, and also says not to open the plug-in unit's door while energized. CYA I assume.