Condition monitoring of cable aging via time-frequency domain reflectometry in real-time

For condition monitoring, time-frequency domain reflectometry is adapted in the instrumentation and control cable of nuclear power plants regarding thermal stress. Cable samples are accelerated thermally aged to a higher than the normal operating temperature. While thermal stress is afflicted to the cable samples, TFDR has been implemented to measure the reflected signal and assess the condition of the cable in real-time. A transition in cable status can be observed during each test which apparently is an indication that thermal stress affects cable condition. Furthermore, the phase variation of the reflected signal is estimated to analyze the impedance variation. Experimental results show that TFDR can be used to monitor the condition of cable for thermal aging process.