Flashover Properties of PEEK–FSR Interface of Underwater HV Electrical Connector in Extremely Hot and Humid Environment

Abstract

Underwater high-voltage electrical connectors (UHECs) are the key equipment of power supply for deep-sea engineering, which often work in extremely hot and humid underwater environment, and the polyetheretherketone (PEEK)–fluorocarbon silicone rubber (FSR) solid–solid interface in UHEC is the weak part urgently needed to be studied. In this article, a scale model is employed to simulate the solid–solid interface in UHEC, and the flashover properties of the PEEK–FSR and PEEK–silicone rubber (SiR) interface in different hot and humid environments are systematically studied. The results show that the dc flashover electric field (Ef) strength of PEEK–FSR and PEEK–SiR can reach 8 and 7 kV/mm, respectively, and show a decreasing tendency with the decrease of interface pressure, with a turning point of ~0.1 MPa. The pressure-dependent cavity size along the interface is thought to be responsible for the variance of Ef. After an accelerated process of hot and humid environment treatment, Ef presents an obvious decrease, and also, the invasion of moisture and the attachment of salt microparticle on the interface are simultaneously observed. The PEEK–FSR interface shows a stronger resistance to hot and humid environment than the PEEK–SiR interface. After 60 h of seawater treatment, water absorption rate of SiR reaches 1.2% and Ef of PEEK–SiR interface decreases by 32%, which are both higher than those of FSR, with a 0.2% water absorption rate and a 26% decrease in Ef. The results provide some useful guidance for the insulation design of UHEC in extreme environment.