By facilitating closed-panel inspections, the use of infrared (IR) windows eliminates 99,9% of arc flash triggers and completely eliminates injuries caused by accidental human contact with energised equipment during infrared inspection. Two types of windows are used, crystal and polymer.
There are claims that crystals possess different levels of energy that can enhance our overall health and wellness. These beliefs are currently outside the testable boundaries of science but many people believe in the mysterious effects that have been reported and claimed. Similarly, many believe that crystal IR windows are the best choice for inspection windows. This belief is false and when tested against the polymer IR window the crystal variety fails miserably.
With a history of replacing a high number of calcium fluoride (CaF2) crystal infrared windows for a mining company in Canada, a power sled manufacturer located in Virginia, USA was fed up. It was discovered that the crystal IR windows were being damaged during transportation from the factory to the customer site.
After investigating why the crystal IR windows had a high rate of failure at the mining site in Canada, it was found that shock and vibration while they were being transported to the site caused them to fail. Crystal windows are known to fail in harsh environments if there is a sudden shock such as an enclosure door being slammed shut or when mobile equipment is moved from one location to another. Ongoing mechanical vibration has also been known to cause them to fail. In addition, water and airborne contaminant absorption over time affects crystal transmission rates in the infrared spectrum. When the 15 kV circuit breaker-based power sleds arrived on site, a significant amount of the OEM-installed crystal windows were broken. For the end customer, this was a warranty issue and the power sled manufacturer was replacing a high number of crystals in the field. Unfortunately the crystal windows were only warranted for ‘manufacturing defects’ and the warranty claim back onto the window manufacturer was denied.
The lead engineer from the power sled manufacturer considered many options. After months of research on IR windows, it was possible to convince the mining customer to convert to more robust reinforced polymer IR windows from IRISS. These had the following key benefits:
• NEMA 6/IP67 protection rating
• Construction from stainless steel for harsh mining environments
• Fixed and Stable Transmission (FAST) for consistent infrared transmission rates over the life of the window
• Imperviousness to shock and vibration
• Unconditional lifetime warranty on the IR window for the life of the electrical equipment.
The installation service was completed outside of manufacturing hours during a Christmas shutdown. Remembering that the first rule of business is not the maximisation of profit but the prevention of loss, the client has now implemented a solution that allows its personnel to safely and efficiently perform routine inspections on critical electrical infrastructure.
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