High voltage direct current – A challenging condition for an electrified society
Many of the systems we are involved in use direct current. Solar cells, batteries and fuel cells all provide direct current, which are also products that are increasingly common in several industries.
A key safety feature of all these electrical systems is the ability to galvanically isolate parts of the system with a contactor. If this is done under load, as in an emergency situation, an arc is always formed which is much more difficult to break when it is direct current compared to alternating current. This is due to the fact that alternating current passes through the zero voltage state fifty times per second, during which time the arc is naturally extinguished. When it comes to direct current, it is constantly at the same voltage level which makes it more difficult to extinguish. An electric arc has a temperature of about 20,000 degrees and is still live. If not extinguished quickly, it can lead to personal injury, welded components and a fire in the system.
To ensure safe extinguishing of the arc, we use a permanent magnet that moves the arc into an open arc chamber. This technology differs from round gas-filled contactors that rely on gas to extinguish the arc. In the event of a short circuit in a system with batteries, for example, a lot of energy passes through the contactor, resulting in extremely rapid heating of components. Our technology is based on an open arc chamber that can safely handle the energy without building up explosive pressure. This allows the power to be safely cut off regardless of any critical failure in the system.
We at Industrikomponenter AB have long experience and great technical knowledge of contactors for high voltage DC since we have delivered to the train industry since the beginning, where 750-1500VDC is common and safety is in focus.
If you want to know more or have any questions, feel free to contact Andreas, Christoffer or Jonas with us!