Study on Contact Failure Mechanisms of Accelerated Life Test for Relay Reliability

Shujuan WANG  Qiong YU  Li REN  Wanbin REN  

IEICE TRANSACTIONS on Electronics   Vol.E92-C   No.8   pp.1034-1039
Publication Date: 2009/08/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E92.C.1034
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Development of Electro-Mechanical Devices (IS-EMD2008))
Category: Relacys & Switches
relays,  accelerated life test,  load current stress,  failure mechanism,  failure model,  

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Electrical life is an important parameter to estimate the reliability of a relay, and it is greatly affected by load current. In order to shorten the time of life test, load current stress accelerated life tests were carried out by using a life test system designed for relay in this paper. During the life test, many parameters such as the contact resistance, the closing time and the over-travel time of relay were measured for each operation to identify the failure modes. After the life test, the failure mechanisms under each current stress, which cause the same failure mode, were analyzed by investigating the variations of parameters and observing the morphology of contact surface. In addition, for the purpose of further studying the consistency of failure mechanisms between different current stress, a Weibull statistical analysis was adopted to estimate the shape parameter of Weibull distribution because the same shape parameter means the same failure mechanism. Finally, a statistical model for estimating the lifetime under load current stress was built. The research methods and conclusions mentioned in this paper are meaningful to perform the accelerated life tests for other types of relays.