Key Technology Research Of The High Current DC Disconnector

The high current DC disconnector is an important part of the ITER PF converter power supply system. It has two main functions in the system: In the close state, rated current and short-circuit current could run through it credibly; and in the open state, main circuit could be isolated reliably. Existing ITER DC disconnector is blade-structure, conductive area is small of the line contact form. And its contact has poor flow ability, leading to large volume of the disconnector. Electrical contact is an important component whose contact resistance determines the overall voltage drop and temperature rise of the disconnector, and influences the current-carrying capability. This article was trying to improve the design of contact, in order to get contact with high current-carrying capacity.In the contact design process, the contact resistance is one of the most important parameters. In this article, contact resistance model of rough surface in the form of spherical and flat contact has been established. And its influence factors have been researched. This paper has also proposed the self-adaption multi contact structure and verified its current-carrying ability. After that, overall structural design and thermoelectric analysis of the straight-line disconnector has been done.In this paper, with the form of spherical and flat contact, the classical electrical contact theory has been reviewed, combined with the description method of rough surface, contact resistance model of rough surface has been introduced. After that, quantitative research between the contact resistance and these factors such as pressure, plasticity index and surface roughness has been carried on.Contact resistance was tested on the experiment platform. Through contrast analyzing of theoretical model and experimental data, results showed that when the load is small, experiment measurement is coincident with the theory model calculation contact resistance; when the load is high, the theoretical model has limitations.This article has also carried on the theoretical analysis and experimental tests of the relationship between the number of contact point and contact resistance within the unit area. By using multi physical field finite element analysis method, the temperature and current density distribution of the structure were showed up. The highest temperature rise of the contact and the maximum current density were figured out of different number of contact point. The simulation analysis and test indicate that with the increase of contact number, temperature rise was significantly reduced. Thus proves that the multi contact structure could improve the flow ability.For multi contact structure form, a new type of straight-line disconnector structure has been design, which could significantly reduce the volume of the disconnector. Overall thermal performance of the disconnector under the rated current is analyzed by using the finite element method, which proves the disconnector could meet the requirements.