The Research And Development Of Intelligent Test System Of Moulded Case Ciruit Breakers(MCCB)

Overload delay protection function, the tripping ability when overload current exceed the defined range, is one of most important technical index of MCCB. Tripping time depends on the length of screw above bi-metal strip inside MCCB. For improving the test efficiency of MCCB, an intelligent test system of MCCB was designed to ensure the tripping time conform to the national standards with flexible manufacturing technology, modern test technology, distributed control technology and intelligent control technology. The main work and innovation points of this paper as follows.(1) The overload theory was analyzed and the mathematic model was build, a set of screw-nut adjustment mechanism with function of lifting, rotating and deflecting was designed, which can dynamical adjust the length of screw above bi-metal inside MCCB. The screw-nut adjustment mechanism is one of the biggest innovation points in this paper.(2) According to the principle of strong current generator, the high current closed-loop system was designed with steady flow controller, electronic voltage regulator, transformer and current transformer, which can provide 0-1500 A test current exactly.(3) The expert system of intelligent test system of MCCB was designed based on CLIPS, which includes high current parameter adjustment, test time adjustment, angle parameter adjustment, stepping motor control parameter adjustment. As one of the innovation points, expert system makes the test result more exactly.(4) According the idea of centralized management, the upper computer WINCC software was designed. According the idea of modular design, the lower computer PLC control software was designed.At present, the intelligent test system has been operated in the company and obtained good test result.