Research On The Measurement Technology Of AC Resistance Of Conductor Based On Automatic Current Comparator Bridge

With the continuous development of the power industry,high-voltage,highcapacity power cables have become a development trend,and the demand for largesection power cables is increasing.For the AC system,the current carrying capacity of the cable conductor mainly depends on the AC equivalent resistance of the conductor,and the AC equivalent resistance is the effective resistance of the conductor to generate heat and heat.The effects of skin effect and proximity effects have received much attention in cables.However,the measurement of the AC equivalent resistance of large-section cable conductors has not yet formed a widely accepted test technique.Based on the above reasons,it is necessary to study the measurement method of ac equivalent resistance.Based on the existing test technology,this paper proposes a fully automatic measurement system based on FPGA and flow ratio bridge.Compared with the traditional current comparison bridge,the bridge is adjusted by adjusting the number of turns.Compared to the balance,the bridge uses a controllable compensation current to achieve a current comparator ampere-balance design.The system can reduce the technical requirements for the operator under the premise of ensuring the measurement accuracy,and the measurement time is short to reduce the influence of the temperature rise on the AC resistance of the large-section cable conductor.According to the test method proposed in this paper,the test system is designed from two aspects of hardware and software.In terms of hardware,the design,simulation and manufacture of the hardware equipment required for testing are introduced in detail,including the design,simulation and manufacture of the current source controlled by high current and voltage,and the design and manufacture of the current comparator.In terms of software,based on virtual instrument technology,labVIEW language is used to develop and program the control system,and the manmachine interaction function is finally realized,which greatly saves the cost of testing system hardware.Finally,combining software and hardware structures,the simulation test system,the cable conductor of 70 was and 10 was 1 m from each as a sample to be tested,the test system has carried on the experiment,again with HIOKI IM3570 impedance analyzer compares and analyses the test results of the experimental results show that the proposed test system which can realize milliohm resistance measurement with 1% accuracy.