This is a master thesis project carried out during a 20-week period in the spring of 2020 and that corresponds to 30 credits. The project covered concept development of a contactor (switch for controlling high current). The client ABB Control Products in Västerås, Sweden, have noticed an emerging need within the megatrend electrification in line with a growing energy demand. This comprises a new 1-pole DC-contactor (direct current contactor) within the application of EV-charging (electric vehicle charging). The problem, that this project has been based on, was to create a theoretically functioning concept for a 1-pole DC-contactor based on the client's existing 2-pole DC-contactor. In addition, some other requirements for the concept (formulated as project objectives) have also composed the problem. The research question below has been formulated as a support for carrying out the project. “How can a 2-pole DC-contactor be redesigned into a 1-pole DC-contactor, applicable in EV-charging?” By answering the research question, the project sought to contribute with a value that describes the general benefit of the project by what the concept brings in relation to the growing energy demand. The project has been carried out by using several product development methods that have led to a result which is a theoretically functioning concept. The concept has been presented as a CAD-model, it consists of three main sections: the bottom, the middle and the top. The sections consist of different components that together constitutes the concept. The concept has been able to mimic existing product to such an extent that it can be perceived to fit into the same product family. The core of the concept is that it is estimated to be capable of conducting current at 3000 A and breaking it at 1500 V. By taking advantage of the concept, which in consultation with the client has been considered to consist of a good overall solution, the further development of the new contactor can proceed towards industrialization. This, in despite to the fact that not all project objectives have been fulfilled. In future work it is recommended to develop certain areas of the design in order to later proceed to, among other things, testing the strength and conductivity of a future prototype. The project has resulted in an economic value and a scientific value due to a pending patent of a solution which has helped to make the concept work. In addition, the developed concept has created an opportunity to be able to charge heavy vehicles and charge more vehicles with higher power and higher speed. Thus, the concept has contributed to the megatrend electrification. Finally, the value generated by the entirety of the project can be summarized to that the concept can contribute to a more sustainable future in line with a growing energy demand, where more people choose renewable sources using electric vehicles for transportation.

The master thesis is focused on a remanent magnetism of electromagnets of DC contactors. In the first part of the thesis deals with the formation of a magnetic field in different kinds of materials, description of their magnetization and sorting. The next part is focused on the principle and history of an electromagnet. Negative effects and remanent induction of the contactor are described in the end of the theoretical part. The second part is a practical part. First, the reaction times were measured on a pair of DC contactors. Using the obtained data, an electronic circuit was designed to minimize the difference in switching times of the given DC contactors.