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1. Wrong IP (Ingress Protection) rating
Depending on the environment and installation conditions of the enclosure, a different degree of ingress protection (IP) is required for cooling equipment such as filter fans. Choosing the correct IP rating depends on what the cabinet will be exposed to. Such external factors include the presence of water, presence of dust and solid bodies, presence of corrosive substances and chemicals and solar radiation. The panel needs to protect the electrical equipment from these factors by ensuring the IP rating is adequate depending on the type of indoor or outdoor application and the usage environment.
Protection from the ingress of dust is rated between 1 and 6 – 6 being dust-tight for up to eight hours. Protection from the ingress of water is rated between 1 and 8 with 8 offering protection against the effects of immersion in water for long periods. Axair’s Fandis fan filters offer up to IP56 with the use of a stainless steel cover. They also supply the highest rated cooling fan at IP68 for more extreme conditions.
2. Dirty filter media in the fan or inlet
When a filter fan is used to aid ventilation, it is necessary to replace or clean the filter media to prevent the build-up of dust and dirt. This can affect the performance of the fan and hinder effective ventilation. The frequency that the filter media needs to be cleaned depends on the amount of dust present in the environment and the operating time of the filter assembly. The cover of the fan or inlet can easily be removed to check the state of the filter media and wash if needed. This will ensure good air flow whilst maintaining the required ingress protection. Filter media can be washed up to 10 times and are very inexpensive to replace. A rating of IP54 can be achieved with G3 filter media and IP55 with G4 filter media.
3. Ignoring direct solar exposure
If the enclosure is installed outside, it should not be exposed to direct sunlight as the heat from the solar radiation can combine with internal heat sources and cause the temperature to rise. In some cases, it could rise above the threshold required for the proper operation of the devices. The simplest way to avoid this is by placing the enclosure in a north-south orientation, reducing the total surface area exposed to the sun. Another easy solution is to paint the enclosure in light reflective colours or in a highly polished stainless steel to reflect the sun’s rays, therefore, reducing the effects of solar radiation. Another cost-effective method is a sunshade, which keeps sun off the enclosure all day.
However, it is not always possible to avoid sunlight so extra steps should be taken with outdoor enclosures to deal with the impact of solar radiation and the drop in temperature at night. For example, thermostats should be used to control the fan and heaters to maintain a constant temperature during the daytime and night time. This will aid climate control by reducing the cabinet temperature in the day and heating the cabinet to avoid condensation formation at night.
4. Internal layout of the enclosure
In order to improve the efficiency of thermal management, the layout of the equipment inside the enclosure needs to be given consideration. Grouping equipment close together creates unwanted ‘hot spots’ as cool air cannot move around the space to dissipate the heat generated by the equipment effectively. To allow air circulation, the equipment needs to be evenly spaced, respecting the recommended distances between the various devices.
5. Live voltage with enclosure door open
When the electrical panel needs attention, the power supply should be switched off for safety reasons and the ventilation equipment should stop operating in order to prevent dust or dirt from entering the enclosure. A solution to ensure the voltage is off when the enclosure door is opened is the use of a limit switch device that mechanically activates to interrupt the electrical voltage. This simple safety feature is good practice and reduces the ingress of dust during maintenance works.
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