<p class="MsoNormal" style="text-align: justify; line-height: 115%">Data obtained from surveys suggest that majority of the industrial and domestic fire incidents are due to electric short circuits. Hence, monitoring the operation of the electric power box is of utmost importance. The precursors to the failure of electric power box are primarily overheating, tripping and arc/spark at the electric joints. Some of the reasons for the overheating of electric joints; are improper connection, loose crimping and incorrect wire size. This paper reports on the implementation of ultrasonic waveguide sensors for the online monitoring of electric power box. Waveguide sensors are increasingly used in Structural Health Monitoring (SHM) due to their advantages such as simplicity, accuracy, ease of installation and cost-effectiveness. In this work, we test the critical electric power box sub-components namely: Miniature Circuit Breaker (MCB), Solid State Relay (SSR) and contactor. A pair of wire waveguides are used simultaneously to monitor the overheating as well as the tripping of the MCB. While one waveguide functions as an ultrasound temperature sensor, the other acts as an acoustic emission based arcing sensor. Experimental trials are performed for different parameters of overheating such as current rating, improper torque, variations in surrounding temperature, absence of lugs. The temperatures at the point of overheating for the aforementioned case studies are verified using Resistance Temperature Detectors (RTDs). The temperature gradient can be precisely measured over the length of the waveguides at multiple points. A 10-15 mm gauge length was used. Multiple units can be monitored using a single waveguide by positioning the measurement gauge lengths at each sub-component. The perturbation caused due to the tripping is captured successfully using the passive acoustic emission data from the acoustic waveguide sensor while the local temperature measurements along the waveguides at each sub-components were also acquired using the active ultrasound sensor. This is extended to detect the location of the occurrence of tripping in the case of multiple MCBs. Both overheating and tripping occurrences are captured simultaneously by the waveguide transducer system. This work has potential applications in industrial sectors in order to ensure workplace safety and improve reliability.</p>

Online Monitoring of Electric Power Box Using Waveguide Sensors

Paper Proceedings: https://asmedigitalcollection.asme.org/qnde/QNDE2021/volume/85529

ASME 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE2021)

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