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Power fans for cooling elec­tronics

The digital world is devel­oping at a breath­taking pace. However, cooling is becoming a chal­lenge, both in telecom­mu­ni­ca­tions and automa­tion. It’s hardly possible to install more powerful fans or increase the number of them, as compact solu­tions are in demand and noise protec­tion require­ments must be complied with. A new compact fan from ebm-papst is a future-proof alter­na­tive, as it delivers up to 50% more air perfor­mance than conven­tional solu­tions.

Today, elec­tronics cooling is mainly based on axial compact fans, espe­cially because they are easy to inte­grate and deliver high air flow rates thanks to the prin­ci­ples involved. However, axial compact fans have their limits, for example if ever-more powerful elec­tronics are housed in the same space or have to be made even more compact in telecom­mu­ni­ca­tions systems or data centers (Fig. above).

To increase the cooling capacity, two axial compact fans are simply connected in series, which, in prac­tice, is usually achieved using counter-rotating rotors. This kind of two-stage fan design results in a higher pres­sure in prin­ciple, but the system also has signif­i­cantly higher noise levels. This means that it doesn’t fulfill stan­dards and guide­lines for noise protec­tion, such as those from NEBS (Network Equip­ment Building System), OSHA (Occu­pa­tional Safety and Health Admin­is­tra­tion), ANSI (Amer­ican National Stan­dards Insti­tute) or ETSI (Euro­pean Telecom­mu­ni­ca­tions Stan­dards Insti­tute). Addi­tional noise reduc­tion is gener­ally not an option, as it requires too much space and drives up the costs.

New devel­op­ment approach for a convincing solu­tion

Fig. 1: Compared to a conven­tional fan solu­tion, the new DiaForce delivers up to 50% more air perfor­mance and also gener­ates signif­i­cantly less noise. (Photo | ebm-papst)

So the special­ists at ebm-papst chose a new approach to develop a fan that delivers more power without being louder and yet is compact. The St. Georgen, Mulfingen and Shanghai sites pooled their exper­tise. In close consul­ta­tion with a major elec­tronics manu­fac­turer, the DiaForce (Fig. 1) was devel­oped, a new compact fan that can meet the future require­ments of elec­tronics cooling in all respects and whose dimen­sions are the same as a conven­tional two-stage solu­tion.

The concept behind the new devel­op­ment is convincing, but the DiaForce’s secret lies in the unique geom­etry of its impeller and housing. This mini­mizes turbu­lence in the edge area, resulting in a signif­i­cant reduc­tion in noise. The fan impeller’s outlet opening is also larger than the intake opening. This means that air flows through the fan in both an axial and radial direc­tion, which ensures a high pres­sure increase (Fig. 2).

There­fore, the DiaForce is char­ac­ter­ized as being between an axial and a centrifugal fan. The basic axial design, which is cheaper to install, remains. A partic­ular advan­tage in terms of aero­dy­namics is that the DiaForce offers an air perfor­mance curve with no dip. At the same time, aero­dy­namic opti­miza­tions make it the quiet­est fan with this power density (Fig. 3).

Fig. 2: The typical pres­sure increase in the DiaForce: at the oper­ating point marked blue in the example, the DiaForce reaches over 17,000 rpm with a power consump­tion of 516 W. This results in over 1,800 Pa in pres­sure and >500 m³/h in air perfor­mance. (ebm-papst)

The compact fan has up to 6 dB(A) lower noise emis­sions than a conven­tional axial compact fan and has up to 50% higher air perfor­mance. The higher air perfor­mance is often not required in normal oper­a­tion, as fans that cool elec­tronics often operate at partial load. However, a suffi­cient power reserve is crucial to ensuring that the elec­tronics continue to func­tion suffi­ciently under condi­tions outside normal oper­a­tion. For example, if the air condi­tioning in the room is faulty and the ambient temper­a­ture rises, there’s enough of a reserve avail­able to speed up the fan as required.

Powerful and intel­li­gent DC motor

The devel­opers have also taken an impor­tant step with the motor­iza­tion. The driving force behind the compact fan is a three-strand, energy-effi­cient DC motor with a motor power of 500 W. The motor design is very compact and oper­ates at high effi­ciency. The newly devel­oped 500 W elec­tronics have a lot to offer: a powerful micro­con­troller is at the heart of the intel­li­gent motor regu­la­tion. It enables maximum possible torque in all load ranges and provides optimum effi­ciency and struc­ture-borne noise. The inte­grated locked-rotor protec­tion ensures safety. A config­urable control input and various optional output signals are avail­able as inter­faces. Prac­tical options include a signal go/no go alarm, an alarm with a speed limit, and an internal or external temper­a­ture sensor. The DiaForce is now avail­able in size 120×120 x86 mm.

Fig. 3: A direct compar­ison between a single-stage axial compact fan (a), a two-stage axial compact fan (b) and the new DiaForce diag­onal compact fan (c). (Photo | ebm-papst)

Intel­li­gent main­te­nance concepts with FanCheck

The optional FanCheck func­tion also enables intel­li­gent main­te­nance concepts to be imple­mented: Fans are usually replaced unex­pect­edly when they fail. If the fans cool elec­tronics that have high avail­ability require­ments, such as in data centers or mobile commu­ni­ca­tion base stations, they have to be replaced very quickly. Some service concepts also stip­u­late that all the fans in the system have to be replaced if this happens. This often leads to signif­i­cant outlay because of mate­rial costs and because service tech­ni­cians have to travel to instal­la­tion sites. The FanCheck func­tion from ebm-papst solves this problem.

FanCheck contin­u­ously calcu­lates the statis­tical service life of the fan during oper­a­tion based on the actual oper­ating condi­tions.

This allows the replace­ment process to be planned cost-effec­tively and enables reduced replace­ment costs. In addi­tion, it increases the avail­ability of the devices. The customer can specify at which time and in which way the fan is to provide status infor­ma­tion or warn­ings. It can monitor the remaining service life closely or trigger a simple alarm when the remaining service life goes below a previ­ously set value. In this way, FanCheck can be easily inte­grated into existing control systems. This means that there’s nothing standing in the way of “intel­li­gent” and high-perfor­mance elec­tronics cooling, as set out by Green­In­tel­li­gence, for infor­ma­tion and commu­ni­ca­tion tech­nology in future.


When it comes to choosing the right drive or fan, it’s not just product char­ac­ter­is­tics, such as energy effi­ciency and perfor­mance values, that are crucial but also the intel­li­gence and commu­ni­ca­tion options that have been imple­mented. Exam­ples of Green­In­tel­li­gence solu­tions for venti­la­tion and drive tech­nology include data acqui­si­tion using internal and external sensors, data processing, intel­li­gent regu­la­tion of high-perfor­mance motor control systems and options for inte­grating the system into networks.

Thanks to condi­tion moni­toring, users can keep an eye on the oper­ating para­me­ters of their system at any time and carry out a better error analysis and opti­miza­tion because the oper­ating history is docu­mented. Demand-oriented and predic­tive oper­a­tion enables longer oper­ating times, mini­mizing energy consump­tion and noise gener­a­tion, and self-regu­lating at different oper­ating states. Predic­tive main­te­nance allows needs-based service work to be planned so that longer service inter­vals and high avail­ability can be achieved with a low number of down­times. 


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