'Thermographic Windows' Article Misinformed
There really isn't any such thing as an Arc Resistant infrared window.
"The Value of Thermography Windows" article (page 32, October 2010) contained several errors.
Statement 1:
"an IR pane is a polymer optic. Both successfully limit physical access (human contact) to live equipment. However, in the event of an arc fault, neither option provides a protective barrier between the thermographers and the exposed conductor and arc flash source. A pane affords little protection because it is a thin polymer with a low melting point"
Response:
An IR Pane is not a polymer optic, it's a term that's used in the industry just the same as IR windows is used. We actually use IR windows as the overall term for the industry and use the term pane to describe a fixed infrared optic in an IR window as opposed to open ports or grills that have no optic fitted.
I manufacture the IRISS range of VPFR polymer-based infrared inspection windows which have been tested above and beyond any other window in the market with major switchgear companies to 63kA, 15kV 30 cycles in compliance with the IEEE testing guide C37.20.7. Even though we have tested to higher ratings than any other company, I refuse to state that we have an "Arc Resistant IR Window" as each and every panel is different, so generic claims of Arc Resistance are extremely misleading and negligent.
Statement 2:
"An arc-resistant infrared window provides a solid barrier between the thermographer and the live conductors in the event of an arc flash resulting from unexpected component failures or work on other parts of the system. Thus, it is possible not only to reduce the trigger effects of an arc, but also to provide the technician with a far safer working environment."
Response:
There really isn't any such thing as an Arc Resistant infrared window.
Statement 3:
"The additional protection afforded by the IR window comes from its crystal optic construction, which is designed to better protect technicians under arc-flash conditions. IR windows can substantially reduce hazard ratings and also help minimize the need for excessively bulky and cumbersome personal protective equipment (PPE)."
Response:
Crystal IR windows cannot even withstand the mandatory impact tests required by IEEE, so how can a 2mm crystal resist one of the most destructive forces on earth -- an Arc Flash event? PPE is minimized due to the fact that the IR window removes the exposure to energized components whilst the operator is surveying the equipment.
Statement 4:
"Thermography windows are a relatively new technology, so there is no specific standard that relates to their construction and testing. However, because they are invariably installed close to arc flash hazards, it is important that windows can withstand not only an arc flash incident but also the rigors of their environment and normal day-to-day operation."
Response:
This is totally incorrect . . . please see the document taken from my book on IR windows regarding this subject.
I deal with this type of spin every day in the maintenance forums that we are a part of, but I really draw the line at a prestigious publication like Occupational Health & Safety being drawn into vendor bashing and misinformation.
Martin Robinson, IEng, CMRP
CEO
IRISS, Inc.
This article originally appeared in the December 2010 issue of Occupational Health & Safety.