Physics and Measurement of Early Wire Insulation Chafing

This paper discusses the physics of development of electrical defects as the result of wire chafing, and how this can be used to extend the prognostics capability of GE's Smartwire Diagnostic System (SWDS). Chafing, a top symptom of failures (37% in one study [ 4 ]) is frequently caused by mechanical vibration of wiring harnesses, which are often strapped to the aircraft structure or run through other types of cable supports (trays, bends, etc.); ambient aircraft structural vibrations are a primary mechanical driver of long term chafing. The US Navy's charter to reduce annual wiring maintenance expenditures by an estimated $57 million provided the driving force for this research effort. No system is available today that can detect and locate a wire insulation chafe without the user disconnecting the wires or passing a high voltage through them. The overall objective of SWDS is to address this gap in wire health monitoring. One of the main goals of SWDS is to detect small wire chafes before they can cause catastrophic electrical failures. The SWDS consists of GE flex sensors, a high-speed data acquisition system and advanced algorithms. In this paper we assess the capability of the sensor to assess various stages of insulation damage, including small but developing defects. The ability to detect very early stages of insulation damage prior to conventionally detected electrical failure is termed “prognostics”. In this paper we will also summarize the present technological barriers to effective and reliable detection and diagnosis of early wire insulation chafing and will discuss the future of prognostic system development for wire chafing in aircraft.Cross Reference: