Research Of Interrupting Characteristics And Static Arc Simulairion To MCCB

Molded case circuit breaker (MCCB) is a low-voltage protection apparatus which made, host and break the normal or non-normal (short circuit current) current. Arc stretched quickly, caused by the separation of static and dynamic contactors when the MCCB is overload or short circuit. Then, arc will be split into a number of smaller ones and tend to quench quickly by the action of plates. High temperature and Repeated burning of arc will reduce property and life span of MCCB greatly, what’s more, it will threaten the reliable operation of the power grid. Therefore, researching on the interrupting and arc movement characteristics is full of important significance. The major contents are followed by these:First of all, A non-contact sensing method of angular rate and angular displacement of MCCB in breaking process is developed based on the laser displacement sensor. By this method, measurements have been performed based on different type of MCCB, NM1-630S-3300 rated at 10A,16A,25A. It is found that different capacity of MCCB has different angular rate and breaking-time. The average angular velocity ncreases with an increase of the capacity of MCCB.Secondly, A transient electro-magnetic coupled model is built for the irregular conductors in the plates chambers based on the finite element software of Comsol Multiphysics. By using the proposed modeling framework, the steady state and the transient responses of the chambers have been studied. In order to verify the model simulations, an experimental device is developed to measure and evaluate the efficiency of the plates chamber. The current supply is generated with a digital-controlled transient current source and the flux density is measured by the hall chips located at different positions. Measurement results show that the magnitude and the distribution of the flux density can be predicted by the proposed model. Different permeability and conductivity have been used in the steady state responses and the transient responses to investigated the efficiency of the chamber. Simulation results show that the efficiency can be increased as increasing the permeability of the plates. The efficiency goes to the saturation if the permeability is increased continuously. The influence of the conductivity on the efficiency is small when the conductivity values are small. By increasing the conductivity, the efficiency of the chamber will be decreased. In the transient response it is found that, by increasing the conductivity, the peak values of the flux density and the magnetic blowout force are decreased. Meanwhile, the rising time is increased.Finally, A flow field, electro-magnetic field and temperature field coupled simulation model of the static arc is built based on the finite element software of Comsol Multiphysics. An experimental device is developed in order to recording the whole physical process of arc based on high-speed phantom, short-circuit test system and data acquisition system. Thus, the dynamic characteristics of arc can be studied on testing and simulation methods, and can be provide experimental and theoretical basis for the optimization design of the chamber.In this paper, the breaking and static arc characteristics of MCCB are studied by using the testing system and the simulation system, and get some results. This results can give a guidance to the optimize design of arc extinguishing system to MCCB.