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Zinc oxide based metal oxide varistors (MOV) are widely used electrical surge protection components. Modern high power, high-density electronics post more requirements such as smaller footprints, higher current density and higher nonlinearity on MOVs. Such requirements can no longer be satisfied by commercially available MOVs due to their limited voltage capability, high leakage current and mechanical cracking related reliability issues, most of which are associated with the presence of non-uniformity, defects and coarse grain in their micro-structures. New formulations and processes have been developed to overcome such limitations. This work has identified compositions that can be sintered at relatively lower temperatures than typical commercial MOVs, but with largely improved I-V characteristics due to refined and uniform microstructure.

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.