A new Zig-Zag Variable Load Test Approach for Enhanced Stray-Load Loss Measurements

This paper proposes a procedure for executing the standard variable load test aimed at obtaining valid correlation factors in the stray-load loss calculation during efficiency measurement. This helps to avoid the tests being repeated, leading to significant amount of time saved, making the proposed methodology of potential high interest for industry. The proposed procedure allows for isothermal multiple readings for each load point of the variable load test; thereby, averaging many measurements of the same load point in order to mitigate the impact of instrumentation and reading errors. Experimental tests on different induction motors show that very high correlation factors for the stray-load losses can be achieved.