Durability Test of Mechanical Winding Switch and Electric Cost Calculation Considering its Resistance Value

Abstract

For the purpose of reducing the electricity cost, we conducted a trial manufacturing of a device that switches the winding connection of a drive motor during operation, and performed a durability test on it. The contact resistance value was initially set to 0.32mΩ. The measurement results showed that the resistance value of the contact with the longest lifetime was 1mΩ or less, up to approximately 80,000 cycles. The variation in lifetime is attributed to the difference in the direction in which the gravity of the short circuit plate is applied to the contactor. To address this issue, we developed a countermeasure by changing the contactor from a flat plate shape to a cylindrical shape. When we applied a mechanical switching device similar to this prototype (contact resistance value equal to 1mΩ), the calculations showed that the electricity cost reduced by 4%.