Voltage tolerance curve (VTC) of sensitive equipment to voltage sag is important for user to apply the mitigation equipment. Test on the equipment is the straight method to get VTC. The accuracy of VTC and the test workload depend on the test method. This paper compares the current five test methods and proposes a new test method for sensitive single-phase equipment. This paper builds a test platform to test the tolerance of a PLC by the six methods, the test results verify the advantage of the proposed method.

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