10kA强直流电流标准源的研制

文中研制的10 k A强直流电流标准源由18路600 A电流源并联至汇流排,进行大电流输出。其精度达100 ppm/a。该标准源采用了新型宽频直流比较仪技术,开关电源并联的分布式电源系统,以及全面的过压、过流、电流开路保护系统等。通过实验对600 A源进行性能测试,其短期稳定性均保持在10 ppm/min水平。该标准源具有高精度、高安全性、操作智能化、检定自动化等优点,为建立直流大电流量值传递体系和检测规范提供了依据。

用霍尔器件测量强直流电流的研究与应用

1强直流电流传感器的发展简史 直流电流的测量是电测领域中的一个重要组成部分.强直电流的测量是为适应冶金、电解、拖动等领域的发展而将电测量与磁测量集于一起的一个新的领域.

用霍尔器件测量强直流电流的研究与应用

(上接2001年第12期) 4霍尔零磁通比较仪 多单元组合式霍尔零磁通比较仪是我厂研制生产的一种新型直流大电流测控设备,它具有精度高,线性度好,工作稳定可靠,受外磁场和温度影响小.在各种整流设备尤其是可控硅整流设备中能耐受反复启动和闭环控制的脉动冲击及高次谐波的干扰等特点.可广泛应用在冶炼、电解、电镀、氯碱等直流大电流的计量保护和控制中.

强直流互感器采用电压差值法校验的系统误差分析

分析强直流电流互感器校验中电压差值法系统误差产生的原因,推导出电流—电压互感器和电流—电流互感器的系统误差之表达式,讨论系统误差的主体及方法误差的确定,对校验系统所用设备参数,给出了合理的选择范围。

Weibull Statistics in Dielectric Strength of Oil-impregnated Pressboard under Ramped AC and DC Voltages

AC and DC breakdown tests were performed on large populations of oil-impregnated pressboard samples. The effect of voltage ramp rate on dielectric strength has been investigated. A statistical analysis of breakdown data was carried out using the Weibull distribution. The 90% confidence intervals of Weibull graphs were calculated. The study shows that dielectric strength and shape parameter change versus ramp rate. The variations are attributed to the size and number of defects. Discharges occur from the oil to the oil-pressboard interface and lead to breakdown. DC dielectric strength is larger than that corresponding to AC voltage. This is ascribed to the dissipated energy difference under the two types of field and the fatigue produced by the alternating voltage. This phenomenon is related to space charge. Under DC stress, dielectric strength is higher under negative polarity. It is assigned to the different quantities of space charge accumulated under the two polarities.