| Popis: |
Both reliability and lifetime of in-service wooden poles are key information for the management of overhead power line maintenance. Several NDT methods have been developed in the past in view of a residual strength evaluation. Based on more than ten years of research, a new concept for the security and maintenance of wood supports has been developed. By considering the fundamental hypothesis that the weak point of in-service poles is located at the ground line, a new NDT concept based on both local moisture content and local density measurements has been improved. Measurements are available using a pair of electrodes with a length of 40 mm, driven into the wood by a simple mechanical system. Using isolated electrodes, moisture content can be measured in the pole, without influencing external conditions. Using a strength sensor, local compression (expressing local density) can be accurately measured. Both variables are driven by an integrated electronic instrument display by showing green and red lights for both applications-security and maintenance. Measurements in the field on in-service poles and cantilever bending tests on the same sample were supported in order to define the calibration models. |
