【摘要】 直流电流互感器现场校准存在较强的电磁干扰和其他不确定的环境因素,因此现场校准用直流电流标准器不仅需要具有较高的测量准确度,还要具备较强的抗电磁干扰的能力。首先利用ANSYS软件对用于现场校准标准器的磁调制式直流电流比较仪磁屏蔽结构进行了建模仿真,分析了屏蔽层厚度、屏蔽材料的磁导率以及气隙对屏蔽效果的影响。根据仿真结果,完成了直流电流比较仪磁屏蔽结构的设计。其次,通过仿真分别分析了无磁屏蔽结构和有屏蔽结构条件下,母线偏心和邻近外导体所产生的干扰磁场对直流电流比较仪测量准确度的影响。最后,完成了额定参数为5 000 A:5 A的直流电流比较仪样机的研制,并通过测试验证了仿真设计的有效性,所研制的直流电流比较仪整体准确度达到0.005级的应用要求。更多还原

【Abstract】 Strong electromagnetic interference and some uncertain environmental factors exit when the direct current(DC) transformer is calibrated on the work field. Therefore,the standard DC current comparator should not only have much high measuring accuracy,but also require the strong ability to resist electromagnetic interference. Firstly,the paper establishes the simulation model of the magnetic shielding structure of the direct current comparator(DCC)based on magnetic modulator with the ANSYS software,which is used as the reference for the field calibration. The influence of the thickness of the shielding,magnetic conductivity of the shielding material and gap on the magnetic shielding effectiveness is analyzed. According to the simulation results,the design of the magnetic shielding structure is carried out. Secondly,this paper analyzes the influence of the eccentric bus and interference magnetic field generated by the nearby conductor on the measuring accuracy of the DCC without and with the magnetic shielding structure respectively. In the end,the prototype of the DCC with the nominal parameter of 5 000 A:5 A is developed. The testing results of the prototype confirm the simulation results and the effectiveness of the designed structure. The total accuracy of the developed DCC is up to 0. 005 level,which is satisfied with the requirement of the applications.更多还原