电缆屏蔽效能的评估与分析
发布时间：2019-06-03 01:56
【摘要】：电缆的转移阻抗是评估外界的电磁场能量通过电缆的屏蔽层的参数。测量电缆转移阻抗是衡量电缆屏蔽效能的主要方法,其理论模型在很早以前已经提出,之后也不断有依据各种简化的假设条件并加以改进的模型。如需要获得比较准确的参数,应对转移阻抗作实际测量。线注入法、吸收钳法以及三同轴法是目前主要的测量方法。本文选择三同轴法。三同轴法顾名思义,是将被测电缆芯线、被测电缆屏蔽层以及外回流圆管固定在同一轴线上,形成三同轴结构。测量电流的波形采用8/20μs波形。根据电缆屏蔽层性质的不同,对屏蔽层为编织带型的电缆注入1千安、2千安、3千安的电流,对屏蔽层为钢铠型的电缆注入1千安、5千安、10千安的电流,分别测量了一些不同型号电缆的转移阻抗。测量过程中还考虑了不同的分流方法,分别采用了无分流、铜带分流、扁钢分流以及铜带扁钢共同分流的方式。由所得数据分析,低频下,电缆屏蔽层的扩散对于电缆的转移阻抗起到决定性的作用,使其更接近于直流电阻;高频下,转移阻抗随着频率的增大而迅速增大,主要原因是由于外界的电磁场能量通过电缆屏蔽层上的孔洞与电缆的芯线发生耦合作用所致。此外,还根据理论公式作电缆转移阻抗的理论值计算。对实际测量的结果和理论计算的结果作对比,分析误差产生的原因。引入了套穿编织带的方法,与这种注入电流的方法作对比,分别测量了一些不同型号电缆的转移阻抗,在共有频段内,两种测试方法所得数据比较一致。
[Abstract]:The transfer impedance of the cable is the parameter to evaluate the external electromagnetic field energy passing through the shield layer of the cable. Measuring cable transfer impedance is the main method to measure cable shielding effectiveness. Its theoretical model has been put forward a long time ago, and then there are constantly improved models according to various simplified assumptions. If more accurate parameters are needed, the transfer impedance should be measured in practice. Line injection method, absorption clamp method and triaxial method are the main measurement methods at present. In this paper, the triaxial method is selected. The triaxial method, as the name implies, is to fix the measured cable core line, the shielding layer of the measured cable and the external reflux pipe on the same axis to form a triaxial structure. The waveform of measuring current is 8 / 20 渭 s waveform. According to the different properties of the cable shield layer, the cable with braided belt type is injected with 1, 2, 3, 3, 000, 1, 5, 10, 000, respectively. The transfer impedance of some different types of cables was measured. Different shunt methods are also considered in the measurement process, including no shunt, copper strip shunt, flat steel shunt and common shunt of copper strip flat steel. From the analysis of the obtained data, the diffusion of the cable shield plays a decisive role in the transfer impedance of the cable at low frequency, which makes it closer to the DC resistance. At high frequency, the transfer impedance increases rapidly with the increase of frequency, which is mainly due to the coupling of external electromagnetic field energy through holes in the shielding layer of the cable with the core of the cable. In addition, the theoretical value of cable transfer impedance is calculated according to the theoretical formula. The results of practical measurement are compared with those of theoretical calculation, and the causes of errors are analyzed. In this paper, the method of piercing braided belt is introduced, and compared with this method of injecting current, the transfer impedance of some different types of cables is measured respectively. in the common frequency band, the data obtained by the two methods are consistent.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM75
本文编号：2491583
[Abstract]:The transfer impedance of the cable is the parameter to evaluate the external electromagnetic field energy passing through the shield layer of the cable. Measuring cable transfer impedance is the main method to measure cable shielding effectiveness. Its theoretical model has been put forward a long time ago, and then there are constantly improved models according to various simplified assumptions. If more accurate parameters are needed, the transfer impedance should be measured in practice. Line injection method, absorption clamp method and triaxial method are the main measurement methods at present. In this paper, the triaxial method is selected. The triaxial method, as the name implies, is to fix the measured cable core line, the shielding layer of the measured cable and the external reflux pipe on the same axis to form a triaxial structure. The waveform of measuring current is 8 / 20 渭 s waveform. According to the different properties of the cable shield layer, the cable with braided belt type is injected with 1, 2, 3, 3, 000, 1, 5, 10, 000, respectively. The transfer impedance of some different types of cables was measured. Different shunt methods are also considered in the measurement process, including no shunt, copper strip shunt, flat steel shunt and common shunt of copper strip flat steel. From the analysis of the obtained data, the diffusion of the cable shield plays a decisive role in the transfer impedance of the cable at low frequency, which makes it closer to the DC resistance. At high frequency, the transfer impedance increases rapidly with the increase of frequency, which is mainly due to the coupling of external electromagnetic field energy through holes in the shielding layer of the cable with the core of the cable. In addition, the theoretical value of cable transfer impedance is calculated according to the theoretical formula. The results of practical measurement are compared with those of theoretical calculation, and the causes of errors are analyzed. In this paper, the method of piercing braided belt is introduced, and compared with this method of injecting current, the transfer impedance of some different types of cables is measured respectively. in the common frequency band, the data obtained by the two methods are consistent.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM75
【参考文献】
相关期刊论文 前2条
1 齐磊;崔翔;谷雪松;;屏蔽电缆转移阻抗和转移导纳的宽频测量[J];电波科学学报;2007年04期
2 张琦;石立华;张祥;周璧华;;电缆屏蔽效能评估方法比较研究[J];核电子学与探测技术;2012年04期
，本文编号：2491583
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