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coefficient (NTC) thermistor introduces demand-oriented speed control, where the fan’s control circuitry is able to regulate its activity. This controls the speed and duration of operation, such that the fan is only on when needed and remains off when cooling is not required. Introducing an NTC sensor to monitor the temperature also means that when the fan is on, it operates at the minimum speed required to introduce sufficient cooling, thereby lowering overall power consumption.


Although it offers benefits over traditional


Backward curved blade fans from EBM- Papst use a centrifugal technique to increase airf low


fan design, in the past, this technology has suffered from more complex installation. The plug and play EC cassette fan range from EBM- Papst overcomes this problem with an accurately positioned inlet ring within the eye of the impeller for maximum airflow. It also features mounting arms to avoid noise created by the blade-passing frequencies, as well as isolation mounts to prevent resonance throughout the system.


Filter your selection An EC fan can reduce energy by around 30


per cent over an AC fan, with further savings when using a controller. The use of controllers isn’t limited to integrated circuitry however, and they are also available as external controllers to be used with a standard EC fan.


The EBM-Papst ECMatrix Temperature


Controller is powered directly off the fan’s supply and typically draws less than 10mW. It also uses an NTC thermistor to monitor the temperature and regulate the fan’s activity. In addition to the ACMaxx range, RS currently offers two variants of EC matrix temperature controllers. The temperature controllers come with pre-set temperature ranges, which reduce the fan’s output to 15 per cent when the measured temperature is at or below the lowest point and raises the output to 100 per cent at or above the highest. Fail safe technology to detect an open or short circuit at the NTC is also a feature.


Extending this approach, Pfannenberg’s range of thermostats


and hygrostats use temperature and relative humidity to modify fan behaviour. By adding a relative humidity sensor, the fan maintains the enclosure environment above dew point, thereby providing increased control and extending the operational lifetime of sensitive electronic components.


Increase air flow


As well as sophisticated fan controllers, the design of the fan itself continues to undergo significant development. Manufacturers are developing more efficient fan and blade designs that benefit many application areas. One example is the range of backward curved blade fans from EBM-Papst, which adopt a centrifugal technique to draw air in to the centre of the fan and distribute laterally. This complements EBM-Papst's range of DC axial fans, offering greater air flow, particularly in enclosures where elevated back pressure is evident.


26 | December 2010


The process of cooling sensitive electronic devices using forced air has an inevitable consequence; the need for a filter. In some applications, particularly those where the environment causes blocked filters, the fan’s ability to cool the device is limited and failure can quickly follow, making regular service maintenance visits necessary.


In order to address this


Pfannenberg's Filterfan extends fan life and makes filter servicing easy


potential hazard, Pfannenberg integrates alarm features in to many of its fans. The company has recently introduced its fourth


generation Filterfan, which boasts the ability to increase the air flow in an IP55 installation by 100 per cent over previous generations. In addition, four corner fastening allows easier access to the filter, without the need for tools, while the filter itself is easier to clean.


One demanding customer, a wood mill, has already seen the


benefits of the fourth generation Filterfan, claiming it has extended the time between services by three weeks in some cases, with a commensurate extension to the fan’s serviceable lifetime. Other benefits of this range include a variable direction electrical connection for easier installation, variable airflow direction and a louvre design, as well as the patented filter mat technology.


While electronic devices continue to develop and adopt low


power methodologies, it is unavoidable that buyers will be tasked with sourcing innovative cooling solutions. Forced airflow cooling offers many benefits but hasn’t always demonstrated maximum efficiency.With the new developments now available through RS, that is changing, giving rise to greater efficiency at all levels.


rswww.com www.electronics-sourcing.co.uk


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