Power source impedance measurement system for testing compliance to IEC 61000-3-3

Flicker compliance tests for mains connected appliances rely on a power source and reference impedance network which simulates the mains supply. Assessment of an appliance is achieved by measuring the flicker induced on the power source output by the appliance, which is dependent on the output impedance of the power source and reference impedance network. The value of this output impedance and its associated accuracy are specified in international standard IEC 61000-3-3. A description is given here of a method for measuring this impedance so that compliance with can be verified.