© Photo | ebm-papst

RadiPac: Compar­ison

Impres­sive test results

The results of the opti­mi­sa­tion process are impres­sive, as shown by the “old” versus “new” compar­ison in Figs. 1 and 2. All-in-all, modi­fi­ca­tion of the flow machine brought about a more than 10% increase in the effi­ciency of the RadiPac fans At the same time the noise level dropped by over 3 dB (A). The extra effi­ciency is converted into higher air flows, in other words the new fans attain higher oper­ating points.

Certi­fied test stand

pruefstandAs a certi­fied manu­fac­turer, ebm-papst fully conforms to the following criteria as spec­i­fied for test stands by the guide­lines of the AHU manu­fac­turers’ asso­ci­a­tion:

“An expert report/test report for fans will be accepted if testing was performed in accor­dance with the latest stan­dard DIN EN ISO 5801:12-2010 (ISO 5801:2007 incl. corr. 1:2008) by a named test body on a suction-side chamber test rig and the compo­nent is manu­fac­tured without any modi­fi­ca­tions.”

Authentic oper­ating condi­tions

einbauThe fans in an air handling unit operate in more or less confined spaces. This leads to a reduc­tion in air perfor­mance which has to be taken into con­sideration when selecting the right fan. At ebm-papst allowance is made for the instal­la­tion situ­a­tion.

For compar­ison measure­ments, the test fans are fitted in an AHU housing. Use was made of the dimen­sions 900 x 900 x 760 mm for size 400 fans. For size 560, the dimen­sions of the AHU housing were 1230 x 1230 x 760 mm. All the fans were centrally mounted in the AHU box.

The corre­sponding measure­ments were taken on an offi­cially certi­fied (TÜV) aeroa­coustic fan test stand (c.f. text: Certi­fied test stand) which permits the simul­ta­neous recording of air perfor­mance data and noise values. This chamber or combi­na­tion test rig consists of two low-reflec­tion half cham­bers with high-imped­ance floor conforming to accu­racy class 1 for acoustic measure­ments. Air perfor­mance measure­ments can be conducted at an air flow of up to 100,000 m³/h with a static pres­sure increase of up to 3,000 Pa.

The “old” vs. “new” compar­ison

Fig. 1: The char­ac­ter­istic curves show the “old” vs. “new” compar­ison for size 400 measured on the certi­fied test stand with free air and in installed condi­tion.

Fig. 2: The family of char­ac­ter­is­tics shows the “old” vs. “new” compar­ison for size 560 measured on the certi­fied test stand with free air and in installed condi­tion.

Compar­ison with competing prod­ucts

Fig. 3: Direct compar­ison of size 400 fans with competing prod­ucts in installed condi­tion. The instal­la­tion situ­a­tion is shown above.

Fig. 4: Direct compar­ison of size 560 fans with competing prod­ucts in installed condi­tion. The instal­la­tion situ­a­tion is shown above.


The ebm-papst RadiPac (green curve) was chal­lenged by:

  • A manu­fac­turer who also develops EC external rotor motors (blue) and
  • A company which uses corre­sponding control elec­tronics (red) with PM internal rotor motors (perma­nent magnet).

The diagram shows air perfor­mance, overall effi­ciency and noise gener­a­tion. The char­ac­ter­istic curves speak for them­selves.


EC motors

EC motors have not just proven their worth as a means of driving fans and pumps in build­ings. More and more fans used for cooling switch cabi­nets and converters as well as in modern agri­cul­ture are being fitted with EC motors offering an unbeat­ably compact design and extremely quiet oper­a­tion in addi­tion to outstanding effi­ciency.  


EC motors are very similar to PM motors for example. Both types have a rotor fitted with magnets and the stator carries the exci­ta­tion winding.
By virtue of their design, EC and PM motors are always supe­rior to the widely used asyn­chro­nous motors (AC motors) in terms of effi­ciency. This partic­u­larly applies to appli­ca­tions involving low motor outputs and low speeds.

Attain­able IE classes

The effi­ciency levels currently achieved by the energy-opti­mised motor, a mains-powered perma­nently excited synchro­nous motor (also known as BLDC or PM) are far supe­rior to the values required by effi­ciency class IE4  (as per IEC 60034-30).

Frequency converter oper­a­tion

ebm-papst EC motors already contain the neces­sary control elec­tronics. This offers advan­tages in the event of EMC prob­lems and the unit only has to be connected to one transfer point.   

Typical appli­ca­tions

EC motors have become estab­lished as drive units for fans in many areas, not just for use in build­ings. The external rotor design is ideal for air handling appli­ca­tions, as the axial or centrifugal fan impeller can be mounted directly on the external rotor.

Worth noting

The term EC motor is often used to refer to different concepts. However, as BLDC, EC and PM all describe motors with extremely similar prop­er­ties, the name used is of no great signif­i­cance – the impor­tant thing to remember is that: Genuine Green­Tech EC motors from ebm-papst are designed to operate without poten­tially prob­lem­atic rare-earth magnets.   

System opti­mi­sa­tion: An overall concept with poten­tial

In the power range below 10 kW, the use of effi­cient EC motors can reduce power consump­tion by well in excess of 10%. Savings of 50% and more are possible if this is accom­pa­nied by adap­ta­tion of the air perfor­mance to changing require­ments, in other words by the use of speed control. EC motors in partic­ular operate far more effi­ciently in the part load range than converter-controlled AC motors. Further savings can be achieved by opti­mising the air routing upstream and down­stream of the fan. This is often not possible due to a shortage of space, which is where another outstanding feature of the new RadiPac impellers comes into play: The outflow of air from the impeller is directed in such a way that virtu­ally no loss occurs when it is deflected into the main flow direc­tion in an air handling unit. This illus­trates the system­atic approach adopted by ebm-papst when devel­oping the new impeller gener­a­tion.


All-in-all, modi­fi­ca­tion of the flow machine and the motor brought about a more than 8% increase in the effi­ciency of the RadiPac fans. This can be seen from the differ­ence between the green and black curves.

The full expert report of the ILK in Dresden can be viewed at: www.ebmpapst.com/ilk

You can find more infor­ma­tion about the new RadiPac here: www.ebmpapst.com/radipac

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