Schaltbau at Volta-X

DC contactors and their contribution to the energy transition

Munich, 23/03/2023: Innovative and intelligent energy systems are the centrepiece of the Volta-X trade expo, running from 28 to 30 March in Stuttgart. At the trade fair, Schaltbau GmbH will be showing its latest DC contactors, which offer maximum safety when using direct current.

Improving the way we use Direct Current/DC is vital to the success of the energy transition and to reducing carbon emissions. Electric cars use direct current to charge their batteries, solar cells and wind farms supply energy as direct current, and stationary energy storage systems and all the machinery in a modern factory are also based on this technology.
“Long ago, the decision was made to convert direct current into alternating current between production and use since the latter was considered easier to manage. Energy losses caused by this conversion were accepted. However, with a view to reducing energy use and carbon emissions, people have begun to rethink this strategy and the demand for efficient, high-performance electro-mechanical components that make it safer to use DC technology is increasing,” says Martin Zierer, Manager of Application Engineering at Schaltbau GmbH who will be giving a talk at Volta-X about the challenges and solutions posed by electro-mechanical DC switching.

DC contactors for charging infrastructure

According to a government resolution, the number of charging points in Germany, which currently stands at 70,000, is to increase to 1 million by 2030 in order to encourage people to switch to electric cars before the ban on combustion engines comes into force in 2035. One of the ways Schaltbau is making direct current safer is through its Type C300 single-pole DC contactor. Despite its compact size, this contactor switches high powers required for fast charging. Each contactor has a permanent carrying capacity of up to 500 amps, and in case of a short circuit can even manage 6,000 amps for 20 milliseconds without the contacts welding. Consequently, the contactor can maintain full functionality in order to break high loads where necessary: up to 500 amps and 1,500 V. “Another advantage of our contactors for charging applications is that, unlike many gas-filled contactors, they have mechanically connected contactor feedback circuits which are less error-prone and also function as mirror contacts,” adds Martin Zierer.

Bi-directional contactors for energy storage systems

Energy from wind and solar power systems is not generated linearly. Instead, there are phases of higher and lower energy production. Energy storage systems are therefore required in order to store and release energy as necessary. While these systems have previously been based largely on alternating current, there is currently an increasing demand for direct current storage systems as a way of preventing energy losses. Our C320 bi-directional DC contactors are particularly well suited to exactly these kinds of applications. With a rated making capacity of up to 3,000 amps, our contactors are ideal for high inrush current applications. They have a permanent carrying capacity of up to 1,000 amps, and in case of a short circuit can even manage 4,500 amps for 100 milliseconds without the contacts welding. When necessary, the C320 can break high loads regardless of the direction of current. This bi-directionality is crucial for charging and discharging processes in energy storage systems.

Schaltbau at Volta-X:

- From 9:00 to 17:00 every day at Stand 9B24
- Talk “Electromechanical DC switching – challenges and solutions” @ 10:00 on Tuesday, 28 March on the Volta-X Best Practice Stage in Hall 9

About Schaltbau:

Founded in Munich in 1929 as a developer and manufacturer for the railway industry, today Schaltbau GmbH is a global innovation and growth company providing contactor and safety solutions for the energy, industry, mobility and rail sectors. The technology used in our products and tailor-made solutions is designed for direct current, an important part of the energy transition.


Schaltbau GmbH

Hollerithstrasse 5
81829 Munich


Tel. +49 (0)89/93005-158
Fax +49 (0)89/93005-156

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