FEATURE RACKS, CABINETS & ENCLOSURES
FANNING DOWN Five common mistakes in enclosure cooling
The thermal conditions in enclosures and cabinets directly impact the longevity of the components they house. Therefore, it is necessary to avoid certain pitfalls when the enclosure is cooling, errors that could compromise the equipment’s operation. Axair lists the most common enclosure cooling mistakes and how to avoid them
WRONG IP 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, dust and solid bodies, 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 one and six, six being dust-tight for up to eight hours. Protection from the ingress of water is rated between one and eight, with eight 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 a cooling fan at IP68 for conditions in harsh environments.
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
30 OCTOBER 2019 | ELECTRONICS
at which 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 ten times and is inexpensive to replace. A rating of IP54 can be achieved with G3 filter media, and IP55 with G4 filter media.
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 device. 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, reducing the effects of solar radiation. Another cost effective method
is sunshading, 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. 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 at night.
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.
LIVE VOLTAGE WITH THE
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. To ensure that the voltage is off when the enclosure door is open, one can make 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.
Axair
www.axaironline.co.uk / ELECTRONICS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
