Study On The Mining Flameproof Intelligent Load Control Center For 3.3kV Underground Distribution System

The research project in this thesis is an important part of "Study on Measurement and control system for 8 Set Vacuum Contactors Switchgear in 3.3kV Underground Distribution Network Based on PLC" (20031116), which is sponsored by Science and Technology Department of Shanxi Province. The work is proposed in accordance with the problems exited in the fully mechanized face such as high voltage level, large power equipment, more kind of loads, complicated control modes, difficult trans-information and so on. With the growth of domestic coal industry, it has been the main trend to build up such a mining model as one mine, one pit and one face. On the base of the mining model mentioned above, it is objective requirement to raise the running voltage level from 1140V to 3.3kV in underground distribution network. However, because it is difficult to match the imported mining system with the electrical control equipments made in china, all 3.3kV electrical switchgears have to be imported from abroad in past years. Such a situation has resulted in many limits to develop domestic coal industry due to the high price, long supplying period and some technical index witch can not meet the requirements formulated by national standard GB3836. It is of very important significance to develop the mining flameproof intelligent load control center for 3.3kV underground distribution network.There have been many problems such as simple protective principle, lower reliability and worse stability in motor protection systems at a long time, so that the phenomenon resulted in motors burned out is happened frequently. According to the situation, it is necessary to take the measurement and control system of 3.3kV mining flameproof intelligent load control center (LCC) as the research project in this thesis. The sample system for industrial application has been manufactured. The testing works have been done with the sample and the satisfied results have been achieved as following:According to the field requirements, the general scheme of measurement and control system of LCC is proposed which can meet the requirements of motors which are used for driving the operating properties installed in underground, the protective circuits in the measurement and control system are designed and the technical characteristics are established in the system. It has been shown by experiment results that the scheme is reasonable so as to develop LCC, which lays a foundation to establish the sample system for industrial application.A set of intrinsic safety circuits have been explored and some technical parameters are proposed. At same time, the intrinsic safety characteristics are analyzed and some fault condition are simulated. It has been verified by the experiments that the pilot circuit can not only satisfy the intrinsic safety requiring but also the safety coefficient K of the circuits is greater than the requirements of i_b level , which can increase the safety properties of LCC and prompt the safety production in underground.Leakage protection is one of the three main protections in underground distribution...