Nearly all household appliances that work with air, water or another fluid, such as dishwashers and vacuums, have a filter that keeps particles from penetrating into the machine’s moving parts. This helps avoid clogging of those parts, as well as the cost and inconvenience of replacing them. What’s more, the filter ensures the machine – like a vacuum cleaner – works as it should.
In the case of control cabinets, thermal solutions often have filters. For example, ventilation grilles that let in air may have filters. The same is true for fans and even air conditioners, which in locations with a high rate of pollution need filters to protect their internal mechanisms.
The purpose of an air filter in a grid or fan is to ensure that:
- The air quality flowing into the cabinet meets specifications regarding cleanliness and temperature.
- The cooling function works, thanks to the entrance of outside air that is cool enough – typically less than or equal to 30o.
The effects of a dirty filter
Over time and with extended use, filters will undoubtedly become dirty and will need to be replaced. Doing so as part of a good preventive maintenance program ensures that the dirt in a filter is always below 60-70%, the point at which air flow will be significantly affected.
If the dirt load goes above that point, then the following may occur:
- Greater risk of overheating, if the filters are blocked, the temperature inside the cabinet will increase rapidly. If the temperature climbs high enough, it can top the maximum specified for speed drives, PLCs, contactors, UPS, capacitor banks, electric batteries and other installed equipment. These may then quit working and create an immediate stoppage.
- The interior parts in the active equipment, such as the secondary fans of a variable speed drive, can get impacted because a dirty filter does not work in the same way as a clean one. For instance, smaller particles will enter more easily and with more turbulence, which may cause the secondary fans to not work properly and perhaps not at all.
- More insulation on the surfaces of the interior equipment, especially in electrical and electronic equipment with aluminum radiators on the back. This can produce a greater accumulation of heat by the creation of this extra insulation. What’s more, this may affect areas that are difficult to access and clean.
- If the dust is conductive, it can create even more problems. Mines, steel plants, aluminum factories, and sites that use carbon fiber can all have conductive dust, which poses a significant risk of a short circuit or other issues if it gets inside a cabinet.
- The fans in these dirty filter conditions will not perform their ventilation function correctly because the flow rate through the filter is drastically reduced. It can be cut by more than half in filters with dirt levels around 80% -90%. More Importantly, the energy consumed will rise, the temperature control system will work less efficiency, and the risk of a stoppage will increase.
- The lifespan of the equipment depends directly on the state of the filter. If we assume an installation that normally has 30ºC outside air, then with a clean filter you can roughly equalize the temperature inside and outside the cabinet. On the other hand, with a dirty filter the interior temperature can reach 50ºC. Due to this, the equipment’s lifetime will shorten drastically, perhaps dropping in half.
In conclusion, always have filters of quality that meet international standards EN779 and ISO18600, including anti-fire properties (like M1). The filters also should be kept in a clean state, with a dirt level below 50%. Doing so will allow you to as much as double the life of interior equipment while avoiding safety problems. This will also ensure optimal ventilation considering external conditions, with important savings to Opex and Capex due to reduced maintenance. To learn more, download our control panel technical guide, “How to reduce damage to components through effective thermal management.”