A Safety-Compliant Power Supply for Mobile Air Purifiers:

 8 June 2022
Out of the Box: Air Purification

The influence of indoor air on human health has been known for a long time; it also became a key issue in the discussion about (re)opening schools during the COVID-19 pandemic. By rapidly developing mobile air purification devices, Miele, a family-owned company, hoped to help many families by improving health and restoring a degree of normalcy to their everyday lives. Thanks in part to outstanding collaboration with WAGO, the project has been a complete success.

The significance of infectious aerosols in connection with COVID-19 and the debate on atmospheric particulate limits have once again focused our attention on the huge effect air quality has on our health. Adults breathe more than 20,000 times a day, taking between one half and three liters of air into their lungs each time. These organs are directly coupled with the outside world, so several protective mechanisms exist to ensure that respiration lets as few pollutants as possible into our bodies. But if the pollution level remains constantly excessive, this stress hurts our health, leading to diseases such as bronchial asthma or COPD (chronic obstructive pulmonary disease). Such chronic respiratory diseases are among the top causes of death worldwide. These are very good reasons to be concerned with air pollution control and air purification.

This concern was shared by division of Miele & Cie KG specializing in the manufacture of commercial products: “Even just our experience with clothes dryers has given Miele decades of know-how about blowers and filters. And we’re already using high-performance filters in our medical products too,” explains Bernd Taphorn, the development engineer at Miele responsible for the entire electrical design of the air purifier project. “We wanted to get our mobile air purifiers on the market as quickly as possible, while maintaining our high standards, in order to restore a bit of normalcy to people’s lives in these unprecedented times.”

We wanted to get our mobile air purifiers on the market as quickly as possible, while maintaining our high standards, in order to restore a bit of normalcy to people’s lives in these unprecedented times.

Bernd Taphorn, Development Engineer at Miele

Product Development in the Fast Lane

A key idea, a highly motivated project team, agile methodologies and reliable technology components – a simple summary of the story of Miele AirControl air purifiers. But the reality was sometimes more complicated, as Taphorn well knows: “We had all the right ingredients, and the team did an extraordinary job. At the same time, we pursued new agile approaches in order to keep the development time as short as possible. But we still wanted to ensure 100 % satisfaction with our air purifier in terms of performance, safety, cost-effectiveness and durability – people expect top quality from Miele, after all.”

The team quickly chose the technical foundation: To avoid potentially hazardous UVC rays and ozone and take advantage of the company’s own pool of expertise, the they opted for physical filtration processes. A multi-stage filter system now ensures maximum efficiency: Coarse and fine filters traps particles up to 1 µm in size, including pollen, spores and smoke. An H14 HEPA (High Efficiency Particulate Air) filter, tested in accordance with European standard EN 1822-1, traps 99.995 % of all particles between 0.1 and 0.3 µm in size. This includes airborne substances such as viruses, bacteria and other germs. “Filter performance was only one development consideration,” explains Taphorn: “We also had to consider the air volume and distribution, the noise level of the device and the inactivation of contaminants in the filter. Furthermore, the first official recommendations were published in the middle of the process and were included in requests for tender for public authorities and schools. We were constantly working to incorporate all these considerations.”

Despite shorter development times, nothing is left to chance at Miele: Fluid mechanics modeling allowed the team to determine the perfect size and arrangement of elements in the air purifiers.

A Reliable Power Supply

The blower and heater prevent moisture from collecting in the filter cartridge and also reliably inactivate viruses and bacteria. While these are powered by 230 V mains voltage, numerous 24 VDC loads necessitate a separate power supply unit: For example, Miele AirControls are equipped with controls for efficient automatic operation and have LCDs and multiple measuring transducers. With a CO2 sensor, the device automatically regulates the air purification performance according to the carbon dioxide content of the air. There are also built-in temperature sensors and a pressure sensor. “In selecting the 24 V power supply, we were on the lookout for a compact, reliable unit, and it had to be EN 60335-1-certified,” explains Taphorn.

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A small footprint and fast assembly: WAGO’s Compact Power Supply can be securely screw-mounted to the housing with the mounting clips.

In selecting the 24 V power supply, we were on the lookout for a compact, reliable unit, and it had to be EN 60335-1-certified.

Bernd Taphorn, Development Engineer at Miele

This standard governs the safety of electrical equipment, both for use in household environments and for commercial purposes, and is mandatory for the intended use. Based on the requirements, the development team quickly found what they were looking for. However, there was another challenge: “The exceptional circumstances worldwide have caused supply bottlenecks in many places. We had to make sure delays in component deliveries wouldn’t end up negating the speed of our work,” says development engineer Taphorn. “So we were very glad that we already had a partnership with WAGO for reliable, high-quality components. With its Compact Power Supply, WAGO not only met our requirements perfectly, but could also offer guaranteed high-volume delivery – that made all the difference for the project.”

Full power with a slim design: The WAGO Compact Power Supply (787-1200) reliably powers the 24 V loads in the Miele AirControl air purifiers and meets the electrical safety requirements per EN 60335-1.

Welcome Added Value

“Our product was always able to meet the basic requirements; the customer was essentially able to select the device from the catalog based on the specifications,” recalls Nils Roth, a technical sales representative for industrial customers at WAGO. “But what turned out to be a major advantage for Miele – besides our delivery guarantee – was the picoMAX®Pluggable Connection System, which promises not only total contact reliability, but also efficient fail-safe wiring.” picoMAX® makes dual use the contact force of a single Cr-Ni stainless steel spring – to both clamp the conductor and connect the header pin. This makes picoMAX® much more compact than other pluggable connection systems. Based on the first sample units, the team at Miele was able to plan the cable assembly: “For our assembly process, not having to wire all the conductors individually is a major advantage of the picoMAX® system,” says Taphorn, explaining that “all the conductors are securely plugged and locked in place via female connectors – no tools or additional resources necessary. In the end, we have one plug for the input side, one for the output – that’s it. It doesn’t get much more efficient than that!”

Just one click: The picoMAX® Pluggable Connection System allows efficient fail-safe wiring with total contact reliability – no tools or additional resources necessary.

But what turned out to be a major advantage for Miele – besides our delivery guarantee – was the picoMAX® Pluggable Connection System.

Nils Roth, technical sales representative for industrial customers at WAGO.

To further increase this efficiency, WAGO quickly customized the packaging units, as Roth explains: “Together with Mr. Taphorn, we analyzed the final assembly process and then delivered the power units and connectors separately, instead of in the usual combined sales units. This provides the assembly stations with the right components directly. We also packaged the components in larger units, significantly reducing the packaging material and further supporting lean production at Miele.”

With the AirControl series, Miele has shown that even in turbulent times, it is possible to create great products that will last. These mobile air purifiers not only reliably reduce the viral load in indoor spaces, but also remove particulates, spores and pollen. This can be used to improve air quality in kindergartens, schools and nursing homes and improve human health. Employers can also create a healthier and safer working environment for their employees’ well-being – and that doesn’t only benefit allergy sufferers. “For me, this project showed how a long-term business relationship is especially valuable in difficult periods,” says WAGO sales representative Roth in summary. Taphorn, the Miele development engineer, adds: “It also proved that even in large companies, it’s possible to streamline processes, creating top products – if everyone works together.”

Optimization through coordination: WAGO supported the Miele team not only in virtual meetings, but also directly on site – following all COVID safety protocols.

WAGO Power Supplies Compact

WAGO’s compact and high-performance power supplies in DIN-rail-mount enclosures are available with output voltages of 5, 12, 18 and 24 VDC, as well as nominal output currents up to 8 A. The devices are highly reliable and ideal for use in both installation and system distribution boards.

WAGO Compact Power Supplies is small with high-performance for DIN-rail-mount housings