Investigation on adjustment characteristics of magnetic release used for high speed direct current circuit breaker

Adjustable release is a main component of serialized circuit breakers. The adjustment characteristics of current setting values are very important to evaluate the adjustability of circuit breakers, and have guiding significance to designing and optimizing adjustable releases. To analyze the adjustment characteristics of high speed direct current circuit breakers comprehensively, and to do some base work for choosing and optimizing the adjustment scheme, firstly, we calculated the static and dynamic characteristics of the release with numerical methods. Then, we obtained the adjustment characteristics curves, and adopted the Pearson correlation coefficient to calculate its linearity. Finally, we analyzed the adjustment characteristics in the aspects of adjustment range, linearity, division value, operability, and complexity. The results indicate that the adjustment scheme, which presets the core displacement (d_c) then finely regulates the preload length of disc spring group (L₀), is simple, and has a large adjustment range and good linearity. It is suitable for applications requiring large adjustment range. As for the other scheme which presets L₀ then finely regulates d_c, the division value and the counter force are small. Cooperated with nonlinear scale, the adjustment scheme can be improved. It can be used in micro-motor automatic adjustment or applications requiring higher precision.