The fans used in Uninterruptible Power Supplies are the key components critical to keeping the UPS’s internal electronics and power electronics (used to make up the UPS rectifier and the UPS inverter) within the operational temperature ranges that they are designed to work in, thereby ensuring reliable and safe operation of these components with maximum service life.
Fans that do not operate, or do not operate properly, will not allow the UPS to operate under prescribed conditions from the manufacturers of the UPS components and will hence cause UPS failures and risk to the UPS inverters connected loads.
Generally speaking, fans are found everywhere within a UPS to ensure optimal cooling of components.
As UPS fans are mechanical devices with bearings, they degrade with use over time. Some bearings containing grease are sealed, but the grease dissipates with time and usage.
As the grease dries, the fan’s speed is reduced, and the air-flow through the UPS slows down. Reduced air-flow, in turn, causes higher internal UPS temperatures and the higher heat acts as a catalyst to speed up the drying of the grease in the fan bearings. This will eventually lead to complete fan failure resulting in the UPS overheating and shutting down while putting the connected critical inverter loads at risk.
Dust will also make fans work harder, affect bearings, and shorten fan service life in a UPS.
How Long Do UPS Fans Last For?
A UPS fan can be expected to offer a service life of between 3 and 7 years depending on the environment it works in, especially regarding ambient temperature and dusts levels. To prevent UPS inverter critical loads from being affected, we recommend that UPS fans be replaced every three years as a preventative maintenance practice.
As Capacitors also have similar service life expectancies to fans, many UPS manufacturers recommend replacing the fans and capacitors simultaneously. This common practice is known as a UPS overhaul. It prevents all the fans and capacitors in a UPS unit from failing at once, which will lead to a catastrophic failure and downtime for the UPS inverters.
Almost all Riello UPS system designs include smart cooling, whereby the cooling fans’ speed inside the UPS automatically controls speed and hence air-flow directly proportional with the amount of critical load connected to the inverter at any one time. Products from AROS Riello that include such functions are Sentinel Tower, Sentinel Pro, Sentinel Rack, and NextEnergy.