The IEC1000-4-11 standard concerns testing and measurement techniques that verify the immunity of electrical (and electronic) products from “voltage dips, short interruptions, and voltage variations. Although the standard is European, it is being used as a basis for internal company design verification testing throughout the world. The need for a “standard” for this type of testing is clear. There are many ways to test a product to verify immunity from line variations, and some form of standardization, for comparison purposes, is desirable. However, IEC 1000-4-11 leaves many options available, and does not absolutely specify which tests should apply to a particular type of product.