A Nondestructive Measurement Method for XLPE/SiR Interface Pressure of Flexible Cable Terminal Based on External Deformation Inversion Calculation

The insulation reliability of flexible cable terminals is largely determined by their interface pressure. A timely and accurate measurement of the pressure is hence of great importance for grasping the status of the terminal. Presently the interface pressure of cable terminal is generally measured by a built-in sensor method, which, however, requires sensors to be installed in advance. This will distort the electric field distribution and even induce discharges. Therefore, exploring an effective and nondestructive measurement method for interface pressure of on-site flexible cable terminals has great engineering significance. This article proposes a nondestructive measurement method for interface pressure of cross-linked polyethylene (XLPE)/silicone rubber (SiR) flexible cable terminals based on external deformation measurement (EDM) and its inversion calculation. We first established a mathematical model to build the relationship between external deformation parameters and the interface pressure of the terminal. Subsequently, we built an external deformation measuring platform based on a laser ranger and conducted measurements on real flexible terminal samples. Finally, the measurement results of the EDM method and built-in pressure strain gauges (SGs) method on different cable terminals were compared. The comparison result indicates that the pressure measurement deviation index of these two methods varies within the range of −6.2% to 6.1%, with an absolute error of less than 12.3%, verifying the effectiveness and accuracy of the EDM method.