Message Board Thread - "Infrared Windows"

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Infrared Windows New thermographer 7/21/2005
Are infrared windows the way of the future? As health and safety regulations are trying to put a stop to opening 'live' electrical panels, is the only solution to fit these windows? Is it becoming common practice?
Re:Infrared Windows Tony Holliday (HAWK IR) 7/22/2005

Thanks for the question, its a good one! As safety requirements become more and more focused - especially on arc-flash incedents - then yes, IR Sightglasses (or windows!) are becoming more and more commonplace.

Today, even the OEM's are warming up to the prospect of installing IR Sightglasses into their equipment as a result of increase pressure from end users implementing NFPA70E.

If you are interested in looking at specific applications where IR Sightglasses may be used, you can go to our website and check out the Application Library or alternatively drop me a line and I can send out some hardcopy literature.

IR Sightglasses, in my opinion are simply the best solutino to online IR scanning today. A correctly tested IR Sightglass can withstand the effects of arc-flash and provide a level of efficiency and safety that is unprecedented.

I look forward to hearing from you.

Best Regards,

Tony Holliday
Hawk IR International Ltd.
Toll Free. 1-877-4-HAWKIR
Re:Infrared Windows BWC 8/11/2005
We installed a series of IR windows on a 13.8kv switch that was rescently replaced. They work pretty slick. In other applications, I use an "electrical inpsection" lens that can look through a 1/2" hole. We have several types of covers for these holes and in 4160V this seems to work better than having the whole back cover removed.
Re:Infrared Windows TAC 9/8/2005
Isn't a 1/2" hole in a switchgear or MCC door/cover a direct violation of NFPA-70E that states a clear path to the operator for arc-flash is unacceptable. If an arc-flash occured this 1/2" hole would provide a vent for the explosion and endanger the thermographer, would it not? I also think the ANSI C37.20 standard that metal-clad switchgear is designed to prevents cutting any hole .5 inches and above to maintain ingress protection and safety.
Re:Infrared Windows International Infrared 9/14/2005
Do you honestly believe that cutting a .5 inch viewport hole in a cabinet/switchgear is more structurally damaging than cutting a 3 or 4 inch hole to install an IR window?
If ANSI C37.20 doesn't allow .5 inch hole or greater then how do they allow a 3 or 4 inch IR window hole?
Or does that piece of IR window that breaks at 28 psi make it all better?
Re:Infrared Windows Tony Holliday (HAWK IR) 9/15/2005
Hi there!

This is an excellent post, switchgear guidelines can be confusing at times!

The answer to this question is quite simple really. IEEE C37.20.2 does not allow an aperture - i.e. an open hole - in the cabinet of greater than 0.5" and this is actually a maximum limit depending on dielectric clearances and system operating voltage.


"A.3.3.1 Enclosure openings

When the enclosure is completely and properly installed, openings in the enclosure, other than ventilation openings, should prevent the entrance of a rod with a diameter of 3.2 mm (0.125 in), except that if the distance between the opening and the nearest not fully insulated live part is greater than indicated in Table A.3, the opening may permit the entry of a rod with a diameter greater than 3.2 mm (0.125 in), but not greater than 13 mm (0.5 in)."

This is a safety focused requirement which is primarily in place to prevent foreign ingress into the cabinet, the half inch section is an international standard which is aimed at the cross section of a human finger. The thought being that if the hole is less than 1/2" then a person cannot "poke" a finger into the equipment and touch a live section with the obvious results.

As you can see, it has nothing to do with maintaining the structural integrity of the equipment rather a safety feature preventing severe contact injury. IR Sightglasses with a fixed crystal optic have no aperture as there is a physical barrier between the operator and the live internals at all times.

Not sure where the 28psi comes from, perhaps the cheap plastic optics that are floating around? I am pretty sure that they would fail at around this pressure level or less.

Anyway, the Hawk IR Sightglass C-Range have been successfully pressure tested in excess of 70psi without failure and have survived multiple arc-blast tests to ANSI and IEC standards. No hole can provide this level of safety and protection.

I hope this helps, if this isn't clear please do let me know and I will try and re-phrase!!

Best regards,

Tony Holliday
Hawk IR International Ltd.
Toll Free 1-877-4-HAWKIR

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