Tripping Characteristic Analysis And Matching Design Optimazation Of Electromagnetic Release

Residual current device is an important protective device to prevent personal electric shock and electrical fire accidents in low-voltage distribution network,which can effectively prevent the occurrence of leakage fire accidents and ensure personal and property safety.The driving circuit and magnetic release are the core components of the device,especially in the immunity residual current device,which is driven by the capacitor.The energy storage capacitor and the coil of the release are the key component to ensure the reliable operation of the device.The storage energy of the capacitor directly affects the tripping time of the device,and the reliable tripping requires that the storage energy should not be too low.Therefore,this paper analyzes the factors that affect the tripping of the release,and propose a matching design method of the energy storage capacitor and the coil.The main research work and conclusions are as follows:(1)Based on the analysis of the working principle of electromagnetic residual current circuit breaker,the electromagnetic and dynamic mathematical model and finite element calculation model of magnetic release are established.Through the theoretical analysis of the armature release process and the equivalent magnetic circuit method,the voltage balance equation of the coil circuit,the equivalent magnetic circuit equation of the magnetic release and the armature dynamic equation are determined.The finite element simulation model is used to calculate the magnetic field distribution and static suction characteristics of the magnetic release.(2)The tripping characteristics of the magnetic release are studied.The releasing response states of the armature are simulated and analyzed according to the variation characteristics of the exciting ampere turn under different coil excitation and the magnetic torque received by the armature.Under the excitation of constant voltage source,the armature response state is divided into keeping closed,critical separation and reliable release.Under the pulsed exciting source and capacitor voltage source,there are four response states of the armature: keeping closed,limited separation,critical separation and reliable release.(3)The characteristics of armature angular momentum and angular displacement are analyzed.According to the relationship between the critical angular momentum and angular displacement of armature release under non exciting ampere turns,the reliable release criterion of armature under constant voltage excitation source and pulsed exciting source are determined.The characteristics of ampere turn of coil under capacitor voltage excitation are analyzed,the variation law of armature angular momentum and angular displacement is studied,and the reliable release criterion of armature under capacitor voltage excitation is determined.(4)The influence factors of armature release under capacitor voltage excitation are analyzed,and the matching relationship between capacitance and coil parameters is studied.Through the analysis of the variation law of the torque impulse received by the armature when the same energy is stored under different capacitors,the best matching capacitor is determined when the torque impulse is maximum.The minimum capacitor energy storage required for the reliable release of the armature under the best matching capacitor is also determined.The influence of the coil parameters on the matching capacitor and the energy storage required for the reliable release of the armature are analyzed when the coil window area of the release is determined.The matching design of the release coil and the energy storage capacitor is carried out to minimize the energy storage of the capacitor.