Harmonics and voltage fluctuation/flicker tests are part of the EMC testing for low-frequency radiation in power quality, as required by IEC standards for electrical products. In recent years, not only power conditioners but also high-frequency noise from ordinary household inverter products has come to be regarded as a power quality issue. This application note introduces how to use the power analyzer PW8001 for noise countermeasures, covering measurements of low-frequency radiation such as harmonics and voltage fluctuation/flicker in accordance with IEC standards, as well as methods for measuring high-frequency noise.