Development of Ultrasonic and Microwave Techniques for Detection of Decay in Wooden Cross-Arms
Kaida Khalid, Mohd. Hamami Sahri, Sidek Abd. Aziz, Lai Sook Kean, Ng Kok Cheang and Roslim Mohd.
Most of the cross-arms of the 275 kV and 123 kV transmission lines in Malaysia and certain counties are made of hard wood especially from Chengal species. Due to natural weathering this wooden cross-arms degraded and decay over time. For safety reasons, it is important to have a simple, light, and accurate non-destructive decay detection system.
In this project the microwave reflection technique and ultrasonic method which is based on the transit time have been developed for in-situ measurement. In this study, we categorize the decay on the wood into three stages of decays namely severely decay, incipient decay and sound wood. In the microwave method these stages can be related to the amount of water that can be absorbed by weathered wood and secondly on the wood density at particular moisture content especially at EMC. This method successfully detected inner decay up to 2 cm from the surface of the wood.
In ultrasonic method, an investigation has been done to find suitable method of measurement, especially detection of decay under the metal block. Applying this detection system, the transit times along L-L direction for sound wood, incipient wood, and cracked wood fall under the ranges of 100μs to 200μs, 200μs to 500μs, and above 500μs respectively. To complete the study, several prototypes have been developed, which have been used for field-tests and maintenance work.
FOR MORE INFORMATION, PLEASE CONTACT:
Dr Nayan KANWAL
Email: [email protected]
