Wednesday, January 24, 2007
Arc Flash Concerns During Thermography Inspection
"Infrared cameras have been used to identify problems in electrical systems for many years. Problems in electrical systems manifest themselves by heating. An infrared camera can readily identify these problems in a thermal image, which provides an excellent method of identifying failing or problem components prior to a failure. A failure can disable an electrical system and cause significant lost production, equipment damage and bodily injury. "The above paragraph comes from an article called "NFPA70E, Arc Flash, and Safe and Efficient Thermography Practices" published in the January 2007 issue of Reliable Plant Magazine.
The article points out that thermography, the use of infrared cameras to identify problems based on their heat signature, is a valuable tool for detecting electrical problems before components fail. However, since most electrical components are located within cabinets, those cabinets must be opened to allow for thermographic imaging. The result is exposure to an arc flash hazard.
The article proposes the use of infrared windows. The article states:
"The first rule in any risk assessment is to eliminate the risk if possible; PPE is always a last resort! Infrared windows eliminate the risks associated with live inspections as they allow an infrared camera direct line-of-site access to live electrical components without opening an electrical enclosure. As such, they provide an excellent means of accessing electrical equipment efficiently and safely as a second qualified person is not required to open and unbolt enclosures and the "triggers" of arc flash are not introduced as the panels remain closed."
An extended discussion all aspects of infrared windows, including selecting locations where they should be installed, and how window size can be minimized by moving the infrared camera during imaging.
Labels: Electrical Hazards, Preventing Arc Flash Accidents
posted by Steve Hudgik
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1 Comments:
Informative article. We have been using Mikron SpyGlass ports which use 5/8" holes. Mikron specifies that the NEMA ratings of 1 thru 4 do not apply to the enclosure when the cover in not screwed in place.
A main concern for us is the increasing use of plastic "proximity contact shields".
They are being installed mostly by OEM manufacturers over electrical connections such as transformers, fuses, etc., in machine control cabinets. Does anyone (thermographer)have any thoughts or work arounds on this dilema?
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