Limits for Interharmonics in the 1–100-Hz Range Based on Lamp Flicker Considerations

At present, limits do not exist for harmonics that are non-integer multiples of the power frequency. Any limit developed must 1) be based on some level above which undesirable consequences appear, 2) be measurable by some defined and defensible method, and 3) be as simple as possible. In this paper, limits for non-integer harmonics, here called interharmonics, are developed based on the light flicker effects that such components may cause. Once limiting values are determined based on light flicker using the flickermeter protocol defined by the International Electrotechnical Commission (IEC), they are assessed relative to other physical phenomena, such as overheating, which form the basis for existing integer harmonic limits such as those proposed by the IEC and the Institute for Electrical and Electronics Engineers. The ultimate contribution of this paper is a limit curve for frequencies 0-100 Hz (for 60 Hz systems) that fulfills the three criteria for a limit as previously defined