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

Underwater high-voltage electrical connectors (UHECs) are 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 paper, 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 strength (
E
_f
) of PEEK-FSR and PEEK-SiR can reach 8 kV/mm 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
E
_f
. After an accelerated process of hot and humid environment treatment,
E
_f
presents an obvious decrease, and also the invasion of moisture and the attachment of salt micro-particle 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 hours of seawater treatment, water absorption rate of SiR reaches 1.2% and
E
_f
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
E
_f
. The results provide some useful guidance for the insulation design of UHEC in extreme environment.