Fan filter kits have been in use for around 20 years and are now considered ‘part of the scenery’ and a commodity product. Their function has not changed, they are still as useful as ever; however, if the wrong product is selected, the whole control cabinet may overheat and compromise not only the value of the equipment it contains but also the panel’s primary function, powering a whole process plant, shopping centre or datacentre, for example. The impact of this could be catastrophic so it pays to seek advice and assistance when selecting a system for your power electronics cooling.
In most circumstances, it is not that difficult to select a fan or fan filter for an electrical enclosure or cabinet. All you need to know is the total electrical heat loss within the enclosure and the temperature rise above maximum ambient that the components can tolerate. A simple equation will determine the required air volume flow rate and a well-designed catalogue should identify a suitable product.
For basic level cooling, Axair offer a range of fan filter units with click-fit chevron louvered panels. These are available in three different variants, including a version with standard click-fitting (no tools required), a version with easy access to filter media, and a version with special fixation system to accommodate panel thickness up to 8mm. Available in sizes 105mm to 325mm, the largest unit is designed to filter air at a rate of 650m³/h (without exhaust filter). When an exhaust filter is used, the airflow inevitably drops to about 475m³/h, but if there is sufficient room to accommodate 2 exhaust filters, then an airflow of about 535m³/h can be achieved (for the largest model).
Where the required minimum flow rate is not available from an integrated fan and filter there is an enormous range of axial and centrifugal fans to choose from, either in standard form or within roof mounted units. In some cases it is possible to take a high performance fan and use it conjunction with a number of standard filters, sized to achieve the ideal airflow whilst coping with the ingress protection requirement IP54 or IP55. For hot spot cooling you may look to use either frame axial fans or small centrifugal blowers.
Recent developments also mean that Axair can offer two fan solutions aimed at the control panel industry, based on backward curved centrifugal motorised impellers either in ‘Reverse’ configuration or assembled as a ‘fan module’. Backward curved centrifugal fans overcome high resistance to air flow, can operate without a space consuming scroll housing and crucially are pre-assembled for ease of mounting, saving time and cost.
They also offer great versatility for door, wall or roof mounted installations. Diameters start from Ø180 up to Ø280mm with AC or EC motors (Electronically Commutated). EC fans are increasingly used due to recent European Directive requiring a minimum level of efficiency for fans of a power range from 125Wa to 5kWa. They offer energy saving while operating, but crucially, they tend to offer higher performance thanks to speed set up by electronic and not by the operating frequency. There is also an extensive range of double inlet centrifugal fans, particularly recommended for large heat sink cooling.