A Study On Discharge Theory And Non-Explosion Evaluating Method Of The Intrinsically Safe Circuits For Explosive Atmospheres

The manufacturing of modern coal mines is a digging, mining, transporting and extracting process that based on the high-power electric drive system. Its comprehensive automation is composed of the drive monitoring system, the safety monitoring system and the power distribution automation system. Therefore, intelligent electrical apparatus, field bus technology, and weak power automatic equipment are widely used under mines. Due to the advantages of the intrinsically safe circuit, people are increasingly willing to make use of it in comprehensive automation system control and communication equipment. The testing of the intrinsically safe circuit should be actualized through explosion experiment on the spark test apparatus. In order to ensure the success rate, designers should do some elementary evaluation of the intrinsically safe circuit during the process of research and exploration. However, there is a lack of research on the discharge theory of the intrinsically safe circuit both home and abroad, the slow development of which leads to the difficulty in the design of the intrinsically safe circuits, especially those with higher power circuits. So there is an urgent need for the systematic research of the discharge theory of the intrinsically safe circuit. Besides, if practical non-explosive testing methods can be constructed on the basis of the discharge theory of the intrinsically safe circuit, the designers will find it easier to control the performance of the intrinsically safe circuit, thus resulting in the achievement of shorter researching time and lower costs.The discharge theory of the intrinsically safe circuit belongs to the experimental research area. Therefore, a large number of spark discharge explosive experiments are needed in order to find out the discharge characteristics of different circuits. This thesis has developed the spark test system of the intrinsically safe circuit on the basis of the IEC spark test apparatus. It makes full use of computers'powerful capability to process data, which effectively improves the experiment efficiency and data analysis. Through the large number of explosive experiment discharge waves attained from the spark test system, the thesis analyzes and summarizes the typical discharge characteristics of such basic circuits as inductance circuit, resistance circuit, capacitance circuit and the compound circuit of inductance and capacitance, which provide the basis for the establishment of the basic discharge models of the intrinsically safe circuits. The inductance circuit establishes the exponential models of discharge current. Through the simulation and comparison analysis of actual discharge waves, straight-line model of discharge currents, static Volt-ampere characteristic model and linear Volt-ampere characteristic model, a conclusion is got that the straight-line model actually is the extreme form of the exponential model, while the exponential model of the discharge current represents the actual situation of the open arc discharge of the inductance intrinsically safe circuit. The resistance circuit establishes the parabola model of discharge, which, through the simulation and comparison of the actual discharge waves and linear model of discharge, proves that we can not simply consider the resistance circuit as the special case of the inductive circuit when L=0. The parabola discharge model better describes the power and energy transmission during the process of discharge than the straight-line model. The capacitance circuit establishes the exponential model of discharge voltage. The compound circuit of inductance and capacitance establishes the parabola model of open non-oscillatory discharge current and the constants model of close non-oscillatory discharge voltage. Through the comparative analysis of the simulation results and the actual discharge waves, an affirmation can be made that the above mentioned models can fully describe the transmission process of power and energy during the discharge process of capacitance and compound circuit.This thesis has established the non-explosive evaluating system of the intrinsically safe circuit with ANFIS as its core. ANFIS input eigenvector has been confirmed according to the circuit character, experimental gas types, discharge energy, maximum value of the discharge instantaneous power, the energy ratio exceed the average power value and the discharge time. The system makes use of the explosive experimental data from the spark test system to extract the eigenvector to perform ANFIS training. After the success of the training, the circuit discharge models established are used to extract the Eigenvector to make the evaluation of the non-explosive intrinsically safe performance of the intrinsically safe circuit. According to the explosive experiment, this system boasts high accuracy and practical value.