© Photo | ebm-papst

The kitchen pro

The RATIONAL Self­Cook­ing­Center® white­ef­fi­ciency® prepares deli­cious food in canteen kitchens. The exper­tise of the ebm-papst Group is bundled up inside of the combi steam oven and turns it into an effi­cient system which saves energy, costs and fat.

What would you like today? roast with sauce, fish and chips or assorted vegeta­bles instead? In canteen kitchens guests are now spoilt for choice. The selec­tion is large – as are frequently the portions as well. Putting 300 meals or more on the table in timely fashion is an everyday event as well as a chal­lenge for the cooks. After all, the timing isn’t all that’s impor­tant; quality is also in demand in the canteen kitchens of the world. Chefs are supported in this by the RATIONAl self­Cook­ing­Center® white­ef­fi­ciency®. The combi steam oven prepares food quickly and easily using hot air and steam. Whether meat, vegeta­bles or baked goods, it cooks every­thing to just the right point – at the touch of a button. The cook enters the desired results and then the device controls itself. sensors make sure that nothing gets burned: They detect the size of the food being cooked and the amount of steam added. They check the cooking process up to 60 times per minute and adjust the temper­a­ture, cooking time and cooking chamber atmos­phere. More­over, this has the posi­tive effect of enabling the chef to use 95 percent less fat when preparing.

Alter­nating running direc­tion

Michael Schmidt, purchaser at RATIONAL, with the effi­cient combi steam oven

Since 2004, motors from ebm-papst have been providing optimum air distri­b­u­tion in the cooking chamber. “Previ­ously we used an asyn­chro­nous motor with frequency inverter,” reports Michael schmidt of strategic Purchasing at rational. “Today we work with Green­Tech EC tech­nology. This is qual­i­ta­tively better; in addi­tion, it also saves costs by means of its high effi­ciency.” A corpo­rate restau­rant uses 60 percent less energy by using the combi steam oven. The Mulfingen-based devel­oper met the special customer require­ments for the new series by completely rede­vel­oping the existing motor. Gerhard Gauß, Depart­ment Manager for project engi­neers Germany at ebm-papst, remem­bers, “In prin­ciple, we modi­fied every­thing except for the ball bear­ings – and those we are replacing now as well,” he says with a laugh. The most impor­tant inno­va­tion: Previ­ously the impeller in the cooking chamber always rotated in one direc­tion only, meaning that optimum air distri­b­u­tion was attain­able only with mechan­ical flow aids. “Now we use an impeller that moves air in both direc­tions,” explains Gauß. “The motor changes its direc­tion of rota­tion every minute; conse­quently, we achieve better air turbu­lence without addi­tional flow aids and attain a more uniform cooking result.”

Motor with brains

The EC motor runs smoothly while with­standing grease

The service life of the compo­nents was partic­u­larly impor­tant to RATIONAl. “After all, here we are talking about 30,000 to 40,000 hours in ten years,” says Schmidt. The EC motor with­stands ambient temper­a­tures of 75 °C and even runs smoothly while with­standing grease and chem­ical cleaning agents. “That is impor­tant above all for the shaft, since it comes into contact with the cooking chamber,” continues schmidt. Addi­tion­ally, the motor does not require much space: It supplies the same output despite its reduced size due to its better effi­ciency. “The energy effi­ciency of the EC motors helped us make it even more compact,” says Gauß.

The tech­nology presents advan­tages for control options as well. If things get too hot for the motor due to extreme ambient temper­a­tures in the kitchen, it does not simply switch off. Instead it reduces speed and power. It does not stop completely unless the heat is not abated by this approach. “By means of this ‘power derating’, the device remains usable even under extreme condi­tions,” empha­sises Gauß. And while the previ­ously used asyn­chro­nous motor required 16 voltage versions, the EC motor from Mulfingen does the job with only two. This is made possible by a wide voltage input of 100 to 240 volts. Different power frequen­cies are no longer a problem; one device for normal appli­ca­tions with single-phase current and a second for three-phase AC suffice.

Gas or elec­tricity?

Gerhard Gauß, Depart­ment Manager for project engi­neers Germany at ebm-papst, is happy about the successful combi­na­tion of ebm-papst exper­tise in the combi steam oven by RATIONAL

In canteen kitchens round the globe, many cooks prefer working with gas instead of elec­tricity. There­fore the Self­Cook­ing­Center® white­ef­fi­ciency® can be selected with one of the two connec­tions. Appli­ances heated with gas operate with two gas blowers from ebm-papst Land­shut. They generate the correct gas-air mixture for optimum combus­tion with low emis­sion values. “Depending on the size of the self­Cook­ing­Center® white­ef­fi­ciency® the gas blowers are used in various sizes and perfor­mance classes,” reports Gerhard Gauß.
“Annu­ally we produce approx­i­mately 35,000 units of the self­Cook­ing­Center® white­ef­fi­ciency® and another 10,000 units of our Combi­Master® Plus,” reveals schmidt. RATIONAl produces six unit sizes, begin­ning with six fan trays and a connected load of ten kilo­watts and going up to steam ovens with 20 double plates and a connected load of 64 kilo­watts. “some of the large combi steam
ovens have two motors installed,” says Gauß.

Well cooled

Straight­for­ward and easy to operate: This makes everyday life in the canteen kitchen easier

In all of the appli­ances a diag­onal fan from ebm-papst st. Georgen provides cooling of the stan­dard elec­tronic devices in the instal­la­tion space. More­over, the work envi­ron­ment of the kitchen also places partic­ular demands on the cooling units. Grease parti­cles from frying pans and deep fryers accu­mu­late in the ambient air. There­fore a filter in the rear panel of the combi steam oven protects the elec­tronics from grease deposits. “However, the filter results in a higher pres­sure,” explains Gauß. ”With convec­tion alone venti­la­tion would not be possible; we have to actively suck in the air through the instal­la­tion space. This is why we have used a fan.” The compact devices from st. Georgen have been tried and tested in real-world use for this task with their high power density and a 230-volt direct connec­tion.
As far as the inner processes of the combi steam oven are concerned, the cook notices nothing, but the result, in turn, is all the more evident – not just in the cooking itself. The device requires little space, is energy-effi­cient and, since it is easy to work with, employees can operate it without special training, which saves on personnel costs. And perfectly prepared meals are all that make it to the plates, even by the hundreds.

See how the RATIONAL Self­Cook­ing­Center® whit­ef­fi­ciency® works

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Diagonal compact fans

More pressure with a significantly higher air flow