基于改进TFDR法的核电站仪控电缆断裂缺陷检测

Fracture detection of I&C cable in NPP based on improved TFDR method

时频域反射(time-frequency domain reflectometry,TFDR)法具有成熟便捷、分辨率较高的特点,广泛应用于各类电缆的故障测距。为了有效判别和精确定位核电站仪控电缆绝缘屏蔽层断裂缺陷,文中通过介入热应力,提出一种改进TFDR法。对50 m多芯仪控电缆进行不同程度的断裂破损模拟,并使用传统TFDR法和改进TFDR法进行检测实验验证。检测结果显示,改进TFDR法对弱断裂缺陷的定位峰峰值为0.2,是传统TFDR法的2.5倍,且不同程度断裂缺陷下定位误差率均小于2.5%。可得出如下结论:相较于传统TFDR法,改进TFDR法使用热应力浮动方差曲线作为缺陷判别的依据,可显著提高对弱断裂缺陷的判别能力;改进TDFR法通过对原定位距离进行修正,进一步提高了对弱断裂破损的定位精准度,可实现对微弱缺陷的有效识别定位。

Time-frequency domain reflection(TFDR)method has the advantages of maturity,convenience and high resolution,so it is widely applied to locate defects in various cables.To ensure the fracture defect of the instrumentation and control(I&C)cable can be effectively discriminated and precisely located in nuclear power plant(NPP),an improved TFDR method is proposed by intervening thermal stress in this paper.Subsequently,different degrees of fracture defects are simulated in a 50-meter multi-core I&C cable,and traditional TFDR and improved TFDR methods are used for detection and verification.Comparing the detection results of both,the peak localization of improved TFDR method for weak defect fracture is improved to 0.2,which is 2.5 times of the traditional TFDR method,and the localization error rate is less than 2.5%.Compared to the traditional TFDR method,improved TFDR method utilizes the thermal stress fluctuation variance curve as the basis for defect identification,the identification power of weak fracture defects can be substantially improved.The original localization distance can be corrected to improves the accuracy of weak fracture damage in improved TFDR method.So the effective identification and localization of weak defects can be further achieved in improved TFDR method.