Track 1 Session 2

10:50 to 11:50 a.m. Wednesday, October 13, 2010

Effective Use of Accelerated Tests for Designing Reliable Products at the Best Cost

Highly accelerated life testing (HALT), step-stress testing and quantitative accelerated life testing (QALT) can help engineers to understand the robustness of their design more quickly without the need for long cycling tests. This session presents an example of the application of accelerated testing in motors. The motor winding plays an important role in the robustness and life of the motor. The recent surge in the price of copper is forcing companies to optimize copper usage more than ever before to stay in the fray. Step-stress and HALT types of tests give a good insight about the motor windings by giving us a qualitative idea about their robustness for life in comparison with a motor for which we have some field data and followed by quantitative accelerated life testing. The most important thing is to have some theory behind anticipated failures and to have the right stress factor for winding failures for a specific failure mode. The basic theme is to get knowledge about failure modes by "testing until failure" more quickly than conventional "cross the standard line" testing (also called "test to pass"). By doing so, we learn more about failures and the associated mechanisms; and we test very quickly.

Key Words: Step Stressing, HALT, QALT, Life Stress Models, Induction Motor, Windings, Shaded Pole Motor

Sumeet Bhat and Pramod Yadav

Whirlpool of India Ltd