Martin Robinson, CEO of IRISS and developer of the IR Polymer Window explains the importance and necessity of IR Window certifications. The minimum requirements necessary for certifying a product to UL standards are usually sufficient to ensure the safe and reliable operation of the product; is that statement true or false? Well, in the case of an infrared (IR) window this is not necessarily true as specific application details must be factored in before its use can be deemed ‘safe’.

UL is a US based, Nationally Recognized Testing Laboratory (NRTL) and worldwide safety consulting and certification company that performs safety testing. UL is the only organization to have a defining standard for infrared windows called UL50V. These devices are basically data collection ports for infrared inspection by thermal imaging camera that are designed to allow electrical inspections to be conducted with the utmost safety when the system is under load. They ensure the electrical enclosure remains in a ‘safe and guarded condition’ so the risk of arc flash or electrocution injury is eliminated.

Consider the bigger picture

Not all infrared windows were created equal. Hence, anyone specifying an IR window needs to dig deeper than the UL 50V standard to be 100% confident in the suitability of the chosen window type. This base line standard simply verifies that the window provides a means for passage of infrared radiation but it also carries an important caveat.

UL50V specifically states ‘meeting the requirements for this standard do not assure the window is suitable for use in any application and that suitability for continued use requires additional evaluation as to the performance characteristics necessary for the installation.’

So, what other certifications should you look for when specifying an infrared window? The following provides more detail in defining the functionality and, more importantly, the safety aspects required before attempting to modify an electrical enclosure in any way.

UL/NEMA 50E:
These are environmental standards which apply to electrical enclosures that are intended to be installed and used in non-hazardous locations. These include enclosures for indoor locations only (NEMA types 1,2,5,12, 12K and 13) and enclosures for both indoor and outdoor locations (NEMA types 3 and 3R). NEMA ratings can be self-certified when the manufacturer has third party tests to support the assigned ratings. More common to Europe are Ingress Protection (IP) ratings that can be mapped to equivalent NEMA enclosure ratings with the fundamental difference that IP ratings must be tested and certified by a third party lab.

UL 508:
These requirements cover industrial control panels intended for general industrial use, operating at 1500V or less. This equipment is intended for installation in ordinary locations, in accordance with ANSI/NFPA 70, where ambient temperatures do not exceed 40°C maximum.

UL 746C:
UL 746C is a standard to test performance of polymeric (plastic) components and identifies the ability of a window to withstand impact or flame, an important consideration in the industrial environment.

UL 1558:
UL 1558 is relevant to viewing panes and IR windows fitted into metal-enclosed, low voltage (< 600V) power circuit breaker switchgear assemblies. The standard requires the impact resistance of an assembly to be tested with the window closed; an essential criteria is that is that a 12.7mm diameter rod should not be able to pass through the window or cover.

IEEE C.37.20.2 section a.3.6:
This standard and test procedure for viewing panes mounted in electrical equipment with ratings above 1kV requires viewing panes to withstand both impact and load tests. Unlike UL this does not give any dispensation for material composition of the IR viewing window or whether or not covers are fitted.

The test is simple. It requires that both sides of the IR viewing window be subjected to impact and load and that neither side can crack, shatter or dislodge. For crystal optic based IR windows, this is a requirement that is impossible to meet.

IEC 62271-200:
This provides a controlled arc flash test for 52kV and below metal-enclosed switch gear. The test is performed at 6kV using a current of 31.5 KA for a duration of 0.5 seconds. The procedure determines the amount of pressure and heat installed components on switchgear can survive and still maintain integrity.

It should be noted that an “arc tested” or “arc resistant” rating can only be given to a completed assembly and not a single component within that assembly. Electrical cabinet designs and dimensions are infinite and we cannot and must not use data from one cabinet design to another design unless they are identical in every way.

This is the reason why components, such as IR windows can never carry a generic arc rating and must be subject to standard industry tests to confirm they meet the mechanical strengths and environment properties for each electrical cabinet or assembly to which they are being fitted.

For information on IR windows that are certified to all standards and have undergone more testing than any other brand visit www.iriss.com or fill out the form below to learn more.

Over the years I have been involved in the infrared industry I have seen some mistakes made and problems missed using spot temperature measurements on IR cameras, luckily these were rectified using the IR software when the reports were written… (would not have been the case had we been using “report by exception” techniques!).

I have always trained my thermographers to use area measurement at all times, in particular the “area max temperature function” this way we ensure that we do everything to make sure we don’t miss anything that may be detrimental during the inspection, and this is more important when inspecting through IR Windows!

There are instances when the use of spot temperature measurement techniques are very effective, especially when trying to compare one item to another in an IR image to see what the temperature difference is, or when trying to correlate one component to another, etc…  However as a rule I have always found it best practice to use the area maximum temperature function whilst conducting electrical surveys using IR cameras.

A typical plant is full of equipment that requires periodic infrared (IR) inspection. The challenge, as any thermographer knows, is getting an accurate indication of equipment health. Properly compensating for the various emissivity values of all the components one encounters on the factory floor is possibly the most critical factor in performing accurate and meaningful inspections. Even slight errors in emissivity compensation can lead to significant errors in temperature and Delta T (difference in temperature) calculations. Electrical cabinets are a good example, as they may contain materials with emissivity values ranging from 0.07 to 0.95.

For some components, it can be difficult to determine the correct emissivity value. In the case of a highly polished component like a bus bar, the actual emissivity may be so low as to make temperature measurement impractical. It is strongly recommended that thermographers understand the surface of the primary targets. Once identified, those surfaces should be treated with a high-emissivity covering so that all targets have a standardized emissivity. Thermographers can apply electrical tape, high-temperature paint (such as grill paint), or high-emissivity labels (like the IR-ID labels from IRISS). When all targets have a standard emissivity, refection issues are minimized and measurement errors from reflected ambient energy are greatly reduced. High-emissivity targets of varying shapes can also provide a useful point-of-reference both for the thermographer and the technician making repairs.

Summary
1.    Emissivity is one of the most important variables a thermographer must understand.
2.    Whenever possible, know the emissivity of your target and compensate for it using the emissivity setting on the camera.
3.    Incorrect emissivity settings can have a significant effect on the accuracy of qualitative and quantitative data (thermograms and temperature calculations).
4.    Using an emissivity value that is higher than the actual emissivity of the target will result in electrical faults appearing cooler than they actually are.
5.    Emissivity errors are not linear, but are exponential in nature (Stephan-Boltzmann’s Law). The exponential nature of the error also means that ?T values (differences in temperature) can be greatly affected by the errors as well.
6.    When installing IR windows it is important to standardize the emissivity of the targets while the switch-gear is open (and de-energized).
7.    Common treatments for target surfaces are: grill paint, electrical tape and IRISS IR-ID labels.

To make your job easier during your next electrical inspection, take a look at IRISS IR-ID Labels. Regardless of experience and skill level, thermographers will improve efficiency with IR-ID Labels since any fault diagnosis is only as reliable as the data collected.

 

Many people are not aware that the detector in an infrared camera actually only reads electromagnetic radiation it receives in a specific range of wavelengths. In order to display this in a useful reading the camera makes several calculations in order to convert the actual data to a temperature. The emissivity and transmissivity (sometimes depending on the camera manufacturer) have to be manually entered into the camera’s menuif this value is entered incorrectly the actual temperature will be exponentially different (see Stefan-Boltzmann’s Law) than the displayed temperature. The old saying of “well as long as it is consistently wrong the change will be noted” is not entirely correct either, as the difference between phases will also be exponentially wrong. The error is going to be worse as the temperature rises – if the differential between the measured temperatures is significant then the displayed temperatures could be significantly different!

So that phase imbalance that looks like it is only a couple of degrees different could actually be upwards of 30 degrees! The visual setup of the camera could be the only other way of determining the severity of a potential defect. As anyone who has spent some time looking through a camera will tell you the visual component can be significantly altered (both to make things look better than they are as well as to show “elevated” differentials.) Depending on the level, span and range setup on the camera it would be very easy to miss a severe problem.

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With this in mind it is easy to see why there are so many infrared problems that aren’t caught. In order to ensure that our customers “See What You’ve Been Missing”, all IRISS polymer based windows utilize the same grade and thickness of polymer, so that if you have correctly setup your camera for one IRISS window you can know without any doubt that it is “calibrated” for all IRISS windows. Our Fixed And Stable Transmission (FAST) is exactly what the name implies – unchanging! The ambient temperature outside, length of time in the field, relative humidity or barometric pressure have no effect on transmission rate and therefore no effect on your readings!

IRISS recently announced impressive testing results stemming from three of their products, the VPT and two of their new CAP-ENV IR Windows. (read the press release here).

IRISS’ VPT-100, CAP-ENV-6 and CAP-ENV-12 went under intense testing. The Arc flash test was performed in Poland, and the results were just down right impressive, the IR Windows were Arc Flash tested in line with the requirements of IEC62271-200 (1KV -50KV metal enclosed switchgear) at 6KV, 31.7kA, for 1.1 seconds, (was twice as long as standard tests).  All the IRISS products successfully passed this extreme test.

Unlike Crystal Based IR windows the IRISS VPT and CAP-ENV Systems are the only visual and IR windows that are Impact resistant, maintain a fixed and stable IR transmission and offer the largest FOV (field of view) of any IR window available today.  The IRISS’ VPT and CAP-ENV Series are by far the strongest most durable IR Window systems available on the market today.

IRISS Electrical Maintenance Safety Devices are used in a multitude of industries such as, Power Generation, Manufacturing, Data Centers, Maritime and switchgear OEMs.  IRISS is continuously improving infrared window systems and developing innovative concepts in the electrical maintenance safety device market.  This has led to the creation of the CAP-ENV System, an innovative industrial IR window that could withstand harsh environmental conditions, offering a durable transparent polymer lens that allows visual, UV, and infrared IR inspections to be completed whilst the panel remains in an enclosed and guarded condition.  More information can be found at https://www.iriss.com/emsd-cast-products/cap-series/cap-env-series/www.iriss.com/cap-env.

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