Greetings!
are you using door closed viewports for IR inspection of electrical cabinets? could you recommend any brand and model?

we want to install at our plant some of these viewports to do the IR inspection with closed cabinets instead of opening for inspection, and have found some diferent brands and models, but want to know what experience have you got

thanks for your feedback

Marco:

The industry is generally split between two technologies: Crystal Optics and Polymer Optics.

Your crystal optics are very accurate if you are using a mid wave (MWIR) camera, and if they are being used in controlled environments. Be aware that the transmission is "spectral" (and therefore useful for images but not temperature accuracy) in the Long Wave (LWIR / 8-14µm) range that today's predictive maintenance cameras all use. Your manufacturers here are Fluke and Flir.

The Polymer windows were developed for industrial condition monitoring and are accurate transmitters in the MWIR and LWIR range, are impact resistant and tolerate the industrial environment with degrading, etc. Your options here are Exiscan and Iriss.

All of the manufacturers I mentioned are UL recognized. All the manufacturers have gone through arc resistance testing (which is not as impressive as it sounds). And all will get the job done. Each manufacturer designs their solution a little differently, and as such each fills it's own niche.

I would happy to assist you with any questions you might have. BTW: I am the President of Exiscan.

The angle that you view through the IR window, regardless of the material, affects the image. So it works if you are looking straight on through the window but not if you are looking anywhere other than at a 90 degree angle. So the windows on the market seem to have very limited use. At best you can get images but accuracy is questionable. Since the risk while doing IR scans is minimal I'm not sure why opening the doors is an issue.

the risk is minimal but the risk is there, my boss learned it the hard way !!
the electrician open the door and went away when he showed in front of the gear BOOM !!
this was before the arc flash era and was burn to around second degree,with no permanent damage
customer around here install this in gear with level higher than 4, some higher than 2 depending on there budget

if you have a choice 0 is better than low...

but yes you need some space to be able to put window's in, and you have to put them in the right place

iriss is building some custom design to

thanks a lot for your comments, very useful

NOTE: Not pushing any particular vendor, just offering a listing of requirements/specs to consider, as done for this particular unit that was previously purchased:
On equipment requiring Arc Flash Level II PPE or higher Infrared windows will be installed from the factory at the appropriate locations to view energized parts. The windows will meet the following minimum requirements.
Infrared 3" windows Hawk IR 3" window part number 3" - HWK-075-C-L. Must be tested and approved for UL and Arc flash testing as well as resist water ingression and allow light to be visible through the window in both visible and infrared spectrum. Sight glass must be tested to ANSI C37 and IEC62281-100/200 standards. Warranty for life of installation. Crystal must transmit long and short wave IR designed for installation in power systems operating at any voltage either indoor or outdoor, utilizing a broadband, IR transparent crystal that operates effectively with both long wave and shortwave camera systems. Lens must have protective cover and stainless steel mounting screws. Lens must have passed the following test: IP65, NEMA 3/12, NEMA 1, Arc-flash, and Dielectric Testing - Lightening Impulse 75kV, Dielectric Testing - Power frequency 25kV, Temperature rise @ 2000A, 800A & 630A. Sight glass that has passed these tests is necessary to provide safety to the workers in the area.
Infrared 2" windows Hawk IR 2" window part number 2" - HWK-050-C-L. Must be tested and approved for UL and Arc flash testing as well as resist water ingression and allow light to be visible through the window in both visible and infrared spectrum. Sight glass must be tested to ANSI C37 and IEC62281-100/200 standards. Warranty for life of installation. Crystal must transmit long and short wave IR designed for installation in power systems operating at any voltage either indoor or outdoor, utilizing a broadband, IR transparent crystal that operates effectively with both long wave and shortwave camera systems. Lens must have protective cover and stainless steel mounting screws. Lens must have passed the following test: IP65, NEMA 3/12, NEMA 1, Arc-flash, and Dielectric Testing - Lightening Impulse 75kV, Dielectric Testing - Power frequency 25kV, Temperature rise @ 2000A, 800A & 630A. Sight glass that has passed these tests is necessary to provide safety to the workers in the area.

In addition, the following is some good regarding this topic (all should be available via internet search, otherwise please forward me your e-mail for .pdfs):
1)A Thermographer’s Guide to Infrared Windows
2) Arc Resistant Windows
Fact or Fiction ?
3) How to Calculate theSAFEMinimum Thickness of a Crystal?
4) Infrared Windows and Arc Ratings:
Dispelling the Myth of “Arc-Resistant IR Windows�
[SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][color=#4a6299][font=Arial-BoldMT][color=#4a6299][font=Arial-BoldMT][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][SIZE=5][color=#0f528a][font=Calibri-BoldItalic][color=#4a6299][font=Arial-BoldMT][color=#4a6299][font=Arial-BoldMT][/font][/color][/font][/color][/font][/color][/size][/font][/color][/size][/font][/color][/size][/font][/color][/size][/font][/color][/size][/font][/color][/font][/color][/font][/color][/size][/font][/color][/size][/font][/color][/size][/font][/color][/size][/font][/color][/size][/font][/color][/size]

the problem with manufacturer window installation is that they almost install them dead center to the connections

and most of the time with that configuration you have a hard time seeing all phase coreclty...normally you want to be a bit lower or higher and off center of what you want to check

and if you are in a cable section...the cable installation could and probably will obstruct the window..since cable are often pass in the center of the cell...

and in a infra red guy point of view...bigger is better...go 3 or 4 inch

Regarding Viewing Angles:
Polymers are good for temp and image even at angles.

To the point of of prior post, it is true that crystals are spectral transmitters in the Long Wave (today's imagers) which presents a significant hurdle for temperature accuracy. It is also true that crystals drop in transmission when used at angles (because they are "thicker" when shot at an angle compared to 90 degrees) which will effect temperature accuracy even further. However, they can still provide good images for qualitative use (blue fuse, blue fuse, red fuse = problem). And the image is affected very little by angles, except that the small round housing can eclipse one's Field of View.

To another poster's point, bigger is better for field of view when shooting at angles. So are the shape of the aperture (round windows will crop the image on a square-shaped displays); and the ability to place the lens on the window optic as opposed to shooting from inches behind the optic (think of looking through a knot-hole in a fence -- the closer you are able to get to the knothole, the more you can see).

Regarding Testing and Standards
There is a lot of confusion around this topic. UL 50V is the only IR window standard. It includes an array of tests putting them on par with the enclosures they are being attached to.

Other standards can offer good insights, such as The IEEE C37.20.2 (A.3.6) standard for impact resistance is applicable for switchgear 1000V and higher. This is why we use polycarbonate visual inspection windows today, rather than the tempered glass of yester-year. This test strikes the optic inside and out with a large steel ball, etc etc. among Long Wave transmitters, only polymers are capable of passing this and similar impact resistance tests.

All windows from the major manufacturers pass the UL50V tests and as such are UL recognized (at various Type ratings between 1 and 4X). And all are safer to use than opening gear.

Regarding the "Minimal Risk" of IR Scans
70E dictates use of PPE for thermography since the worker is "exposed to energized conductors" during his task, and since the process of opening the enclosure is "interacting with the equipment in such a manner that could cause an electrical arc." These are two criteria listed in the 70E definition of an Arc Flash Hazard.

In short the open-panel work process is inherently risk-increasing -- IR windows eliminate those risk-increasing behaviors.

I strongly disagree with this. Being exposed to energized conductors is NOT a criteria for an arc flash hazard. The correct terminology would be "exposed energized conductors" and refers to a shock hazard, not an arc flash hazard. An arc flash hazard can exist REGARDLESS of whether exposed conductors exist or not. In most recently constructed MCC's that are properly terminated, there are no exposed conductors even with the doors open because the energized parts are all guarded or insulated. Even during the action of opening the door itself, although there could be just about any situation existing on the other side of the panel, the likelihood of a negative outcome with equipment that is already energized and maintained properly and operating normally is very remote, and the fine print notes in 70E make this case, however wishy-washy they are.

Even if exposed conductors were present, the IR camera itself is not an insulated tool. If this is the case then either the camera (and camera operator) stays out of the restricted approach boundary or the gloves need to come out because it doesn't qualify as an insulated tool. At that point an arc flash hazard is certainly possible but I can't really see a good reason for crossing the restricted approach boundary with a camera.

That brings us to the second criteria. The task of IR scanning itself I can categorically state does not interact with the equipment in such a manner that could cause an electrical arc. There is nothing occurring which is making changes to the circuit (working on energized circuits definition). The hazard is equivalent to "just walking by" which although not in 70E has been repeatedly given as an example of what the 70E Committee feels does not pose an arc flash hazard. The other tasks that we have to be concerned with which definitely qualify as interaction which could cause an arc are tasks such as:
1. Removing bolted covers that expose uninsulated, energized bus work where the panel could fall inward during removal and contact the bus.
2. Probing around with a screwdriver trying to figure out where the hot spot is.
3. Tightening an energized loose fastener.
4. Closing a door on cabling that was improperly installed and not secured and hangs out of the door when it is opened.

For these reasons I would categorically state that IR scanning by itself does NOT pose an arc flash hazard whether the doors are opened or not. However we need to carefully consider the act of opening and closing doors and ANY other activities that go along with IR scanning separately. The existing task tables already (however poorly) address some door opening/closing issues. Anyone doing an engineering study really should be doing the risk assessment as this will be required in the 2015 edition of 70E anyways, and is really what is meant by the term "hazard assessment".

70E dictates use of PPE for thermography since the worker is "exposed to energized conductors" during his task, and since the process of opening the enclosure is "interacting with the equipment in such a manner that could cause an electrical arc." These are two criteria listed in the 70E definition of an Arc Flash Hazard. - See more at: http://arcflashforum.brainfiller.com/threads/2818/#post-13477

IntelliSAW is probably worth looking at. May fit your purpose. Not infrared but a passive sensor to fit and forget with a remote interrogator through the cabinet door that is wired for continuous readings. So a retro-fit or new cabinet job.

[SIZE=3][color=#000000] Polymers are the best solution for industrial applications. IRISS polymer windows are protected by an unconditional lifetime warranty when compared to crystal windows that are limited in life (due to their fragile nature).[/color][/size]

IRISS is the only designer and manufacturer of IR windows providing you the option of crystal (CaF2) as well as both opaque and clear polymer. Likewise, IRISS manufactures both round (VP Series) and rectangular (CAP Series) windows in addition to custom sizes and shapes (Custom Solutions). IRISS brings a full toolbox of options. After all, if all we had was a hammer, every application would look like a nail.

IRISS windows will work with any IR camera and a key element is operator training. Viewing angle can be critical and that is one reason we offer rectangular, custom, and round windows. You can maximize your ability to accurately measure targets while minimizing installation time and manpower as well as the number of cuts in the cabinet. You can select or design an IR window to fit your specific application needs.

Full disclosure: I’m a Sales Manager for IRISS and have over 14 years’ experience in evaluating IR applications and training people in the operation of IR cameras. I am a Level I Thermographer, but not an engineer or electrician. For more info visit IRISS.com

Paul – Thanks for the reply. I don’t think we are far apart as you think. In fact some of what you stated supports my points.

Regarding the Definition of an Arc Flash, and the criteria I mentioned – I was referencing the Information Note #1: “An Arc Flash hazard may exist when energized electrical conductors or circuit parts are exposed or when they are within the equipment in a guarded or enclosed condition, provided a person is interacting with the equipment in such a manner that could cause an electric arc.�

You are correct regarding the arc flash hazard existing even if doors are closed – the hazards of “exposure� and “interacting� are not both required, rather either scenario presents a hazardous work process. As is pointed out multiple times in the document. For example, racking / unracking (that would be “interacting�) is a hazardous task. My point was that opening the panels/doors, is by it’s nature, “interacting� in such a manner, and therefore, the work process which allows for inspecting without a window is hazardous.

Just for clarification, even the act of “Performing Infrared Thermography Outside the Restricted Approach Boundary� is considered a risk, and therefore carries PPE requirements for most of the equipment listed. The PPE levels are reduced by just 1 compared the maximum required for those equipment types, indicating that the committee found the activity not to be the highest risk, but still to be a high enough risk so that it was not reduced by 2 or 3 levels, which other low risk activities are. The next revision will likely declare the act of performing thermography as no risk, but it is still a risk by today’s definition.

Finally, the next revision of 70E will likely break the HRC Classification table into two tables – one declaring whether a task is an Arc Flash Hazard or not, the other indicating PPE level if the task is hazardous. Opening gear will be declared an Arc Flash Hazard whether opening a hinged door or removing a panel. This is consistent with the tables as they exist today. Therefore, open-panel inspections are by definition hazardous since opening the doors or removing panels is requisite part of that work task. The difference is that the worker will wear PPE consistent with the hazard level – in other words, no more reductions in PPE for tasks deemed less risky by the committee.

In summary – the work process for performing an IR Electrical Inspect is hazardous per 70E today, and it will continue to be after the revision for 2014.

Please explain how the arc flash hazard is being reduced and thus merits a "1, 2, or 3" category reduction. If I am performing a task on a panel that is rated H/RC 4 and that task is derated to H/RC 2, and I wear H/RC 2 PPE, exactly how am I protected? This is one of the most ridiculous problems with the existing tables because the 70E technical committee attempted to mix hazards and likelihoods. If the equipment requires H/RC 4 and the only thing that is different about the task being performed is that the likelihood of an arc flash is reduced, the incident energy has NOT changed. I stand a significantly reduced chance of survival while wearing under-rated PPE. Either the likelihood is low enough that no PPE is required, or it's not. Unless the working distance is reduced or some parameter which affects incident energy is reduced such as working on arc resistant gear with the gear closed and latched, or it's not.

Second, can you document any cases where opening and closing doors caused an arc flash? I know of only one case and that was only the case of closing a door onto a pinched cable because the installation was not proper.

Paul:

As the Info Note states, PPE reduction from what would actually be required is "based on the collective experience of the task group." Also, the HRC Category table is conservatively calculated, so in many/most cases, the worker would be over-PPE'd anyway (at maximum levels) -- one of the advantages of actually performing the calculations is that the worker could get by with less PPE (in many cases). But ultimately you are right (and I don't necessarily disagree with you). This is one of the big issues that people have with the tables -- the hazard level is what it is regardless of the risk level. In other words, a 20 cal/cm2 blast is 20 cal regardless of the risk level. But in defense of the committee (as has been brought up on the floor at the 70E meetings more than once) can anyone tell me of a time when someone has been seriously injured as a result of being under-PPE'd due to the table recommendations? Not that I have heard of -- so either the committee did a pretty good job... or they were just lucky. The good news for you and many of the same mind (including me, BTW) is that this is being changed in the next revision cycle after much discussion about your concerns over the years.

As for cases where people have propagated an arc flash by opening a door: ABSOLUTELY!!! I have asked this question of many colleagues on standards committees, and there are countless instances where the arc was caused by opening hinged doors -- the trigger has been due to dust, a loose conductor, a misplaced tool, panels dropped into the enclosure as a result of cumbersome PPE, etc etc etc. The act of opening an enclosure introduces variables into the task -- variables that can and do cause incidents.

you can send me the pdf documents to mlara017@hotmail.com. Thanks for sharing.