The Localizer Of Short-circuit Point Based On Micro-electrical Resistance Measurement Technology

In modern society,electrical appliances play an important role in our life?Electrical safety is not only related to our property safety is more related to our personal safety,so the security problem of household electricity will always be worthy of attention.In the fault of the family circuit,the most common is the short circuit caused by high power electrical equipment.Short circuit fault location technology can speed up the circuit repair and check,reduce the maximum degree of property loss.In this paper,we put forward a set of solutions for the short circuit fault point location of the domestic wire,and the scientific calculation and testing.The difficulty of this paper is the detection of weak signal,focusing on the design of precision constant current source,the design of low noise preamplifier,the design of measurement scheme and the analysis of error model.First of all,this paper carries on the feasibility analysis,proposed one kind of feasible measurement plan.Taking into short circuit fault point will be in the short circuit instant because of high temperature to produce the effect of welding,we choose a measurement scheme is used to avoid the error caused by the short circuit point resistance jump.Secondly,the design of the hardware system of the whole project is carried out.The hardware system mainly has the design of precision constant current source,the design of low noise amplifier circuit,the design of the main control unit,the data acquisition and conversion module,the data display and the host computer communication module.The constant current source is designed by analyzing the working principle of the constant current source to find out the key factors which affect the output precision of the constant current source,and then the improved circuit design a constant current source circuit with good load characteristic and high output precision.In the design of the amplifier,the low signal to noise ratio and high gain are mainly considered.The three stage amplifier circuit is designed by using the operational amplifier with high precision and low temperature drift.Data acquisition and conversion module,mainly is the current reverses secondary measurement system circuit in the thermopower and chemical potential for measurement error is eliminated to the greatest extent,by absolute value circuit,signal judging circuit and high speed A / D conversion circuit design,signal acquisition circuit.Then,the software system is designed.The software system mainly consists of the main control program,data processing algorithm,data conversion subroutine,display program,and so on.Adaptive filtering algorithm is introduced in the software design,which can reduce the noise to the test precision.Finally,the whole system is simulated,the software and the hardware are tested.Based on the analysis of the test and simulation data,the overall performance of the system is evaluated.