I'd be very interested in hearing about the first-hand experiences of anyone who has installed and is using infrared windows or viewports, especially with regard to (1) the installation process, (2) issues with placement, (3) cost justification, (4) results of IR inspections, (5) safety issues or problems and (6) long term durability/use issues.

Clearly more and more people are installing these devices, and with good reason (mainly need for safe access), but I think we can do a better job of learning from our experiences.

Anything based on first-hand experience you can share would be appreciated.

HI John, I have had my customers who have limited access, unsafe access, or for time saving reasons purchase and install the view ports for me to use with the infrared and ultrasound. Wiess insruments has started stocking the mikron view ports so my customers can by direct $50 each. I like them easy access to panels which either couldnt be opened before or were to risky to be around. I especially like that I can use the ultrasound for the detection of corona or arching. Placement can be a problem if I dont explain exactly what I need to see through them other than that the maintenance people if they understand where I need them and why put them in the right place and often I find they put extras in to be on the safe side if they want me to see somthing particularly of interest to them. I can get the IR images very well through the view ports but wish I could get the digital to match (visual pics are allways valuable) I would like to have the same fish eye lens for my digital camera and my corona camera. I dont install and really dont want any part of that I let the customer do it and at $50 bucks each they dont seem to skimp on purchasing enough to keep some on hand just in case. They seem to add a few more every year when we discover new places to put them. The only thing ive noticed is my customers in some cases want to put them in every bucket door so they dont have to open them which doesnt work to well for me because I like to look at coils, transformers, overloads etc. and components are usually too close to use a veiw port. The only thing that really sucks is carrying and changing lenses so I usually ask to do all of the gear that has veiw ports together.

Sorry for the long reply.

Craig

Quick review (my experience):

1) Some customers are installing viewports without direct advise or consultation with their regular thermographer. This occurs after the customer has seen an advertisement or has been approached by a salesperson in the industry. Often these viewpoints will be proprietary - requiring a wide angle lens or some manuveuring with the camera.

2) Most customers will take an educated quess at placement, typically for transforms and high voltage switchgear and rarely with low voltage components. The placement does not always lend itself to an adequate view of the lugs/connections without widely varying the angle of approach. This is a concern.

3) There is a cost justification which is directly related to safety and reliability issues, including frequency of inspection and criticality of components.

4) With adequate placement and when the viewport lends itself to broader views, the results for IR inspections are at least equivalent to removal of covers, dead fronts, et cetera.

5) For high voltage the safety issues are narrowed but to not disappear completely. There are environments in where there remains a need for clearing the area (gas monitoring) when cameras are not intrinsically safe.

6) The viewports appear to possess long-term durability with their simple construction and impact plastic source.

Thermographers can enhance customer relations and improve IR inspection coverage by freely advising customers about viewports, offering options for installing, comparing different brands and assisting the customer in placement.

A visual of the interior of the component (available from the manufacturer) can assist in the placement of a viewport. I would suggest taking an interior specification and working our appropriate angles for viewing. With some large high voltage equipment the client would be served by installing more than one viewport for achieving a full IR inspection of the components interior. This is warranted for components deemed 'critical for operations.'

Thermographers who provide this added value service will find a positive response from the customer, especially if the thermographer is 'arms length' in advisement (does not sell or receive a commission from sale and installation of the viewports).

Craig,

We chose Hawk-IR C-Range sightglasses so we could get visual images through the transparent crystal for reporting and electrician repair orders. Moreover, we use many different cameras and did not want to purchase a proprietary special lens that only works with the mikron camera and their ports. We also did not feel the mikron open .5" hole complies with NFPA 70E as when it is open it exposes a thermographer to "a clear path to energized conductors" which requires wearing the appropriate PPE for the incident energy level available. There is also a possibility of violating the IEEE Metal-clad switchgear design standard C37.20.2(1999) section A 3.3.1 "Enclosure openings" rod test. Remember if you modify switchgear you need to understand the design standards of the equipment so you don't de-rate or de-list the equipment as UL and your insurance company would not like this. Even self insured companies like refiners still have external audits from insurers to verify compliance issues. If you cut a hole in the back door of the gear we wanted a test to prove it would not create a weak link in the door (like plastic windows and open hole would) and Hawk-IR was able to give us Third Party arc-fault test reports verifying their ability to maintain integrity and offer a layer of protection for our thermographers. They are approved by several Arc-Resistant equipment OEMs as well.

Harlan

HI Harlan, thanks for the info but I did a test with my infrared camera and had a 50% loss in temperature measurement at 3' with diffent temperatures with the Hawk IR sightglass and decided I could not suffer that big of a loss in what I do. I do agree there is a potentialy huge problem with installing anything in electrical cabinets since they are rated as manufactured and once altered the rating may be lost I am not 100% sure on that one though but it makes sense. Overall I can see this is a dilema all around for various reasons.

Craig

This message has been edited. Last edited by: Craig Casler,

Craig,

Since I look for hotspots or "Delta T" in the switchgear & MCCs I don't really focus on Absolute temperatures. If one phase is hotter than the other two we investigate. We have a FLIR P65 and it has onboard adjustment for external optics like the Hawk-IR C-Range sightglass and will adjust automatically for the transmissivity losses. You can also do a quick office calibration if you want absolute temps thru the sightglass material. We also use a FLuke Ti-30 for quick inspections and to get absolute temps (if you are in a lab environment etc) we "Office Calibrate" the Ti-30 by doing the following: We take a thermal image of a soldering iron tip without the sightglass and note temp, NEXT we place a spare sightglass in front of the soldering iron and note temp, NEXT we adjust the emmissivity down until the temp thru the sightglass matches the absolute temp without the sightglass. We have tried this adjustment on cable insulation as well to simulate a cable connection and it was accurate to 1 degree Farenheit. Close enough for our government work ;-). Most OEMs only warranty their gear for 18 - 24 months after shipment so warranty voiding is a non-issue on 40 year old gear, and we were provided a UL approval certificate and UL letter for approval for retrofit in the field by Hawk. Our insurance company was more concerned with cover removal and 70E compliance than voiding a 40 year old UL listing in the end.

just my 2 cents

Harlan

Calculating for transmissivity losses is not quite as simple as you have been lead to believe. The transmission rate you calculate by doing it like that is ONLY valid at the temperature the optic is at when you do your calculation and if you happen to have a selective filter. If the temperature of the window material changes then so too does the transmission rate, in the case of large variations the external optic temperature correction may not compensate for this correctly unless you happen to have a selective filter fitted to your camera (very unlikely with the Fluke). As the thickness of the window changes with viewing angle then so too will the transmission rate, so if the thickness of the window changes either with viewing angle or from one sample to another your calculation will be invalid.

DO NOT MAKE THE MISTAKE OF THINKING THIS WILL NOT EFFECT DETLA T MEASUREMENTS. If you have not got this right your delta T will be off, sometimes substantially.