1 The development process of the trip unit The trip unit is a mechanism that enables the circuit breaker to perform various protection functions when the electrical equipment is subjected to overload, short circuit, under voltage, over voltage and the like. The early trip unit was an electromagnetic overcurrent tripper used in air circuit breakers, which only enabled transient protection. With the development of circuit breakers, the rated working voltage, current, breaking capacity and protection functions have been continuously developed, and the trip unit has also developed. After using oil damping, air damping, clock structure, etc. as the delay element, the trip unit realizes functions such as overload delay and short circuit delay. Thermal trippers using hot bimetals have also emerged. By the early 1960s, semiconductor trippers have emerged due to the popularity and application of electronic technology. In addition to the thermal trip unit and the electromagnetic trip unit, the current trip unit has a semiconductor trip unit. Since the 1990s, the protection of low-voltage circuit breakers has followed the international development trend, from electronic to digital intelligent development. After the 0.4kV side reactive power compensation, the power factor target value model and capacity 0.4kV compensation The formula for calculating the power factor target value is shown in Equation 4.2. The value of the power factor target value after 0.4 kV side compensation is not constant. It is related to the load ratio, rated capacity and impedance parameter of the transformer. 4.3 Calculated the value of the power factor target value of the SC8 series transformer under the different conditions, 0.4kV side compensation, the range is 0.9210 (106) ~ 0.93, which can be taken as the target value of 0.93. 4.4 At a certain moment, the investment amount of the capacitor in the automatic compensation device should be controlled by the two quantities of active power and reactive power before the compensation. Drawer Slide Rail,Kitchen Drawer Channel,Kitchen Slim Box Drawer,Soft-Closing Drawer Slides Foshan city boucheron precision hardware co.,ltd , https://www.chinadrawerbox.com