© Janosch Abel

Always well informed

The more infor­ma­tion that is avail­able, the easier it is to keep every­thing under control. Which is why the people respon­sible for upgrading the data center of the Canton of Zug decided on effi­cient fans with MODBUS inter­face.


It is partic­u­larly impor­tant to ensure the best possible storage of infor­ma­tion relating to the judi­cial system, the police and the tax author­i­ties. This applies not just to the encryp­tion and storage of the actual data, but also to the hard­ware on which they are stored. So it comes as no surprise that reli­ably air condi­tioned server rooms are a top priority for the Canton of Zug.

Modern­iza­tion of their recir­cu­la­tion coolers was a prime concern of André Lötscher, Tech­nical Manager of the Canton of Zug Struc­tural Engi­neering Depart­ment. “For years the belt-driven fans in our cooling units have been constantly running to full capacity,” explains Lötscher. “The V-belts required regular checking and had to be replaced in the event of exces­sive wear, and we had to react instantly if they tore.”

“Our recir­cu­la­tion coolers satisfy exacting require­ments”

André Lötscher, Tech­nical Manager of the Canton of Zug Struc­tural Engi­neering Depart­ment

That is why he urgently wanted to modernize the recir­cu­la­tion coolers and replace the old fans at the same time. Further objec­tives were better control char­ac­ter­is­tics and closer moni­toring of the system. Lötscher would only consider complete replace­ment of the units as a last resort: “Our recir­cu­la­tion coolers satisfy exacting require­ments in terms of shock resis­tance for example and cannot simply be replaced by a stan­dard unit. The complete replace­ment of all units would be pretty expen­sive and a lot of work.”

Every­thing at a glance: Thanks to MODBUS-RTU, the fans are perfectly inte­grated into the control system.

So Lötscher made a few inquiries and finally obtained the number of Infra­matic, a small company near Basel special­izing amongst other things in building automa­tion and air condi­tioning systems for all sorts of rooms. Not long after­wards he called Project Manager Stefan Haydn, who came up with a few ideas straight away. He set a date for a visit to Zug, and brought Daniel Spur­geon, Area Sales Manager at ebm-papst, with him.

“This solu­tion makes it easier for us to coor­di­nate the inter­ac­tion of all compo­nents.”

Stefan Haydn, Infra­matic Project Manage­ment

AWhen the three of them inspected the premises and the cooling units, it became apparent that the best alter­na­tive for the Canton’s data center would be to replace the belt-driven fans with EC fans — this would not only get rid of the old fans but also reduce current consump­tion.

“In our discus­sions we also talked about the options avail­able for control and moni­toring of the fans,” recalls Stefan Haydn. “The minute I heard that the ebm-papst fans can be actu­ated and moni­tored via MODBUS-RTU there was no doubt in my mind that this was the course to follow.”

Preci­sion control

In the weeks that followed, Infra­matic first had five recir­cu­la­tion coolers converted. Thanks to the use of RadiFit fans and EC centrifugal blowers with a high power density, the hard­ware retrofit took no time at all. “The fans from ebm-papst permitted virtu­ally 1 : 1 conver­sion, completely straight­for­ward,” says André Lötscher. Instal­la­tion of the RadiFit fans, that were devel­oped for precisely such cases, was partic­u­larly easy.

With regard to control, Infra­matic had a few clever ideas on how to make oper­a­tion even more effi­cient. As the belt-driven fans only had two speed settings prior to upgrading, the temper­a­ture was largely regu­lated by the opening of the cooling regis­ters. The experts completely reversed this less than ideal energy prin­ciple in the converted recir­cu­la­tion coolers.

Stefan Haydn from Infra­matic explains the fine work­ings of the system that controls the fans and the flow control valves.

The output is now controlled via two sequences: In the first sequence, the cooling capacity is regu­lated by the flow control valves and in the second by the fans. This is made possible by the fact that the fans are infi­nitely adjustable. The speed at which the fans rotate is controlled auto­mat­i­cally by temper­a­ture sensors that measure the exhaust air. If the air is too warm, the cooling valve is fully opened and the fans rotate from a defined minimum speed up to the maximum speed. If the air is too cold, the fans turn more slowly and the cooling valve is closed. This ensures that the temper­a­ture in the server room never exceeds the spec­i­fied 22 to 23 degrees Celsius.

A further advan­tage of the fans in the converted recir­cu­la­tion coolers is actu­a­tion via MODBUS-RTU. “It absolutely suits our purposes that the fans, along with other compo­nents in this appli­ca­tion, can be actu­ated and moni­tored via MODBUS-RTU,” explains Stefan Haydn. “That makes it easier for us to coor­di­nate the inter­ac­tion of all compo­nents.” In contrast to a 0 – 10 V connec­tion, MODBUS-RTU allows not just control, but also moni­toring of the fans. They pass detailed data such as voltage and current draw, as well as alarm messages, to the higher-ranking control system for instance. This in turn trans­fers the data to the manage­ment system, which collects infor­ma­tion on all the building services in general. Via the inter­face with a touch panel the admin­is­tra­tive staff of the Canton can thus view indi­vidual values and set various para­me­ters.

Simpli­fied main­te­nance

Well informed thanks to MODBUS-RTU

As compared to actu­a­tion by way of a 0 –10 V signal, the incor­po­ra­tion of fans via MODBUS-RTU offers a whole range of advan­tages. For instance, a fan can not just be actu­ated via MODBUS-RTU, it also passes infor­ma­tion on its oper­ating status to the control system. This includes power consump­tion, current speed, the number of oper­ating hours and detailed error messages. In addi­tion, MODBUS-RTU makes it possible to connect multiple fans with a single cable, thus reducing the amount of instal­la­tion work.

„“The more detailed warn­ings really are a great help,” says Haydn. “They make it easier to see whether a problem is just a passing anomaly or a fault requiring a tech­ni­cian to take a closer look in the server room.” MODBUS-RTU also made control system adap­ta­tion and addressing of the fans more simple for Infra­matic. “With our EC Control soft­ware, customers can check devel­op­ments and para­meter settings quickly and easily,” explains Daniel Spur­geon. “That saves time and is partic­u­larly helpful at the outset of a devel­op­ment.” To ensure even greater reli­a­bility, crit­ical rooms are equipped with two recir­cu­la­tion coolers. These are oper­ated in a master-slave config­u­ra­tion so that all the fans in the units run at the same speed.

Delighted by the simplicity of the process, Lötscher ordered the conver­sion of more units imme­di­ately after modi­fi­ca­tion of the first five recir­cu­la­tion coolers: Once all the systems in the data center had been modern­ized, work started on the venti­la­tion system of the police firing range and head­quar­ters and in an adjoining prison building. “When you have seen just how well the conver­sion works and how econom­i­cally attrac­tive such measures are, you start to realize there are any number of other oppor­tu­ni­ties,” says Lötscher. “What’s more, our air condi­tioning system is now not only more modern, it is also far more energy-effi­cient.”

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