It is crowded in the control cabinet – and it gets hot. More and more elec­tronic compo­nents have to find space in there. Due to the heat given off, hot spots of up to over 90°C exist. Sensi­tive elec­tronic compo­nents have their service life signif­i­cantly limited or, in a worst-case scenario, are destroyed by the heat. Filter fans take care of the needed cooling. They are composed of a fan and a dust filter that prevents dirt parti­cles from getting into the cabinet. Under­neath, embedded in the door of the control cabinet, the filter fan blows cold air towards the inside. It absorbs the heat, causes it to rise and sends it back out through an air exhaust grille.

High-perfor­mance cooling

Thanks to its bayonet coupling: the quick-to-mount centrifugal fan

In the filter fans of control cabinet tech­nology supplier Rittal, the axial fans trans­port the air from outside to inside. “These axial fans have their optimum oper­ating range in low static coun­ter­pres­sure, where they deliver rela­tively large air volumes,” explains Thomas Heli, respon­sible Head of Devel­op­ment Product range EA-2 at ebm-papst in Mulfingen. Should resis­tance increase, for example because of a dirty filter mat, the effi­ciency decreases: the flow breaks off at the impeller and there can be turbu­lence. “This makes the fans inef­fi­cient and noisy,” says Heli. Together with Rittal, the devel­opers at ebm-papst sought a new solu­tion. The result: a new diag­onal fan series, special for the TopTherm filter fans of the leading world­wide system supplier Rittal. “For the user, a high and constant air perfor­mance is partic­u­larly impor­tant”, explains Chris­tine Ronzheimer, product manager and project manager for air-condi­tioning at Rittal. “Aside from that, the fans should be simple to install without tools and be service and main­te­nance-friendly as well.”

With these spec­i­fi­ca­tions, the teams from Mulfingen and St. Georgen went to work: “We quickly recog­nized that the axial fans used for this appli­ca­tion are not the optimal solu­tion. The compact diag­onal fans are much better suited to this,” states Heli. They unite the posi­tive prop­er­ties of axial and centrifugal fans. “The air flow direc­tion of the diag­onal compact fan is, as with the axial compact fans, mostly axial. The pres­sure build-up is, however, increased by the addi­tional centrifugal exhaust compo­nent.” Through this diag­onal exhaust, the inte­rior of the control cabinet is simul­ta­ne­ously cooled and the build-up of hot spots reduced.

Energy-saving and service-friendly

The diag­onal fans have further advan­tages: In the event of a dirty filter mat, perfor­mance degra­da­tion is signif­i­cantly lower despite the higher coun­ter­pres­sure. The mat has to be changed less often and the main­te­nance inter­vals are length­ened. More­over, the new fans save a signif­i­cant amount of energy – above all, when they are controlled over an addi­tional ther­mo­stat: “The control cabi­nets will be cooled signif­i­cantly more effec­tively with the new diag­onal venti­la­tors. With an addi­tional regu­lator it can have a signif­i­cantly shorter run time and an up to 48 percent reduc­tion in energy consump­tion,” Ronzheimer empha­sizes.

The filter is easy to change

Heli makes clear what that means in the real world: “In a produc­tion hall with 200 filter fans, you would save 26,600 kilo­watt hours and about 3,000 EUR in energy costs annu­ally. Viewed over a usage time frame of five years, that amounts to 15,000 EUR.” In order to connect the diag­onal fans to the filter frame, the fans are inte­grated in an inno­v­a­tive housing which, along with the motor bracket with inte­grated guard grilles, also includes the recep­tacle of the connec­tion terminal and an inte­grated bayonet coupling.

Thanks to this bayonet coupling, the fan is quick to mount: posi­tion, turn – all without tools. The direc­tion of air flow can also be changed without much effort. “The cold air should not just be pushed inward, other­wise the warm air has to be actively extracted by suction, and the direc­tion of air flow has to be changed,” explains Chris­tine Ronzheimer. “Up till now, this required great effort.” Now, the venti­lator can be easily released via the bayonet coupling, turned 180° and rein­stalled. A further plus: “With the old fan, the terminal clamps were always fixed in one corner. In extreme cases, the customer had to wrap the supply around the entire fans,” said the product manager. “Now they can posi­tion the terminal clamp flex­ibly in one of four corners – they simply turn the fan.” Quick to mount, the filter fan then takes care of optimum cooling, even in fully packed control cabi­nets.

See the TopTherm fan and filters working