Networks Europe Jul-Aug 2019 - Page 33

UNINTERRUPTIBLE POWER SUPPLIES 33 A look at what constitutes a poor By Power Control When you're looking to invest in a new uninterruptible power supply, naturally, the focus is on the systems’ functional attributes such as battery autonomy, power factor, efficiency, reliability and the initial cost. While these are of course essential, its also important to remember that uninterruptible power supplies contain fragile electrical components requiring stable and precise environmental conditions, specified by each UPS manufacturer, to ensure maximum longevity. Avoiding problems Extreme temperatures are the most common causes of UPS battery degradation, provoking behaviour that’s incongruent to their normal specifications. Nearly all uninterruptible power supply manufacturers will quote a battery operating temperature tolerance typically between 20-25°C. Placing a UPS system in an environment which has a temperature not conducive to its specification will cause the electrochemical reaction in the battery to quicken. On average, for every 8.3°C above the recommended temperature, the life of the battery reduces by 50%. More often than not heat and humidity go hand in hand. Moisture in a high voltage environment can have serious consequences, causing corrosion of UPS cabinets and internal components, or worse a fire. Again, most UPS manufacturers will specify the maximum relative humidity of an environment safe for the UPS, most commonly <95% (non-condensing). For this reason, it’s recommended that a UPS is not installed near open windows or areas containing high levels of moisture. To prevent overheating, an uninterruptible power supply requires adequate ventilation and cooling. The powerful fans UPS environment and how this can ultimately be avoided... draw in air from the surrounding environment to cool the machine down, any dust or corrosive particles in the air will also be drawn in and sticking to the fan blades. A layer of dust could cause a significant blockage leading to overheating and ultimately the UPS system may be at risk of consequential failure. Businesses requiring UPS systems that are located near the coast should take extra precautions when installing. Similarly, to the adverse effects caused by dust, UPS systems located near the coast are affected by the sea air. The fans draw in salty air which crystallises on the printed circuit boards (PCBs) inside the UPS causing them to corrode and potentially short circuit. Assessment is essential Installing UPS systems into such environments demands a detailed assessment of the surrounding conditions of the proposed location. We recommend that the UPS undergoes specialist treatment which includes the internal circuity on the UPS having a silicon-based solution sprayed on them, providing a level of protection against harsh environments. It’s also recommended that any UPS installed in an unsettled environment should have a minimum of two service visits per annum to remove any build-up of dust and closely monitor the resilience. Ultimately, we always recommend that prior to installing a UPS and battery solution, that a room with temperature control, humidity monitoring, and that contains clean air is factored into the budget. Neglecting this crucial criteria can have severe and disastrous consequences on UPS and battery infrastructure. n