Pull the plug! In the world of alternating voltage, this is often heard advice when electrical loads develop an overly unregulated life of their own. In DC power grids, this is a very bad idea that can end in fatal accidents. Until now …
“Disconnecting under load – that won’t happen.” Marc Klimpel, a development engineer at Phoenix Contact, has this statement from DC research circles in his ear when it comes to the origin of the idea of the innovative DC connector “ArcZero“. “For decades, people held on to this view,” he explains. “Disconnection processes were only possible after the power had been switched off”. This is because unsecured disconnection of direct current connections creates an electric arc. This also happens with alternating current, but as the direction of flow of the current is permanently reversed, this extremely short electric arc is barely visible and, above all, has no effect. This is completely different with direct current, because here the one-way electron current does not want to leave its connection and bridges even longer distances with an electric arc during separation attempts. It can burn at several thousand degrees. This does not help either the operator or the material to be cut to be safe and durable.
Frustration through loss
Therefore, until recently, disconnections were only possible after the entire system had been switched off. This meant that DC power grids were hopelessly inferior to AC power grids in terms of safety and ease of operation. And, of course, this approach also reduced the availability of systems. This was much regretted and led to numerous research activities. For one thing, the generation of electricity from renewable sources initially produces direct current. And most consumers also want to be powered by it. But the general grid structure consists of AC power grids, which are safer and much more suitable for transportation over longer distances. So the electricity is transformed on its way from generation to consumption in batteries, displays or PCBs. In the process, some of the energy is lost in the form of heat.
If you wanted to use direct current directly, the connector was usually secured with a lock. The connection could only be disconnected after switching off the system. Not very user-friendly compared to alternating current connectors. For this reason, Phoenix Contact has been researching a different approach since 2018. Marc Klimpel used an existing connector, which is also suitable for outdoor use due to its robustness. With the expertise from pre-development and intensive laboratory tests in the team, the established connector was trained for life in DC power grids.
Extinguishing the electric arc
The long breath in terms of development bears innovative fruit: the “ArcZero” DC plug was presented at the end of 2023. As its name suggests, it keeps the electric arc in check, or more precisely “at zero”. The trick: a small PCB inside the ArcZero monitors the status of the power connection. When the plug is pulled, the PCB suddenly comes to life, draws its energy from the first sparks of the electric arc and extinguishes it within milliseconds.
Developer Marc Klimpel describes the challenges during development: “For us in the BU, having electronics in the connector was new. On top of that, active electronics designed for these voltages – that was also new territory.” The high quality is also underlined by weather resistance up to IP69 and an impact resistance of IK08.
The ArcZero connector therefore receives a 100 percent inspection. Klimpel’s colleague Dat-Tri Trinh accompanies the ArcZero through its laboratory cycles from pre-series development. In other words, he accompanied the prototype from development status to series production. He explains: “Every connector is electrically tested by hand on a specially equipped test table before delivery. This means that all the plugs that go out are tested and marked by hand – and are 100 percent safe. No rejects leave the production line, they are rigorously checked.” This ensures the safety and durability that the ArcZero plug promises. Klimpel and Trinh are certain: “We initially specify it for 500 mating cycles, but it can certainly do much more,” the two developers agree.
Perseverance rewarded
The right product at the right time, because direct current is a real boom topic. And the ArcZero is a milestone in the development of DC technology that is also being recognized in the industry. The innovative plug was voted Electronics Product of the Year 2024 by Elektronik.net, the web service of the WEKA trade media, among others.
