I have a system that consists of a line-connected 120W switching power supply in parallel with a line-connected 450W resistive heater. The switching supply is not 'harmonic corrected', and does does meet the requirements of IEC1000-3-2. The load on the power supply is constant. The resistive load cycles either 100% on, or 100% off (no phase control is used), with 5 minute on & 5 minute off periods.
In order to apply the proper harmonic limits, I need to determine the proper test setup. - While the resistive load is cycled off, the input power is 120W, and the 3rd harmonic current must be less than 120W * 3.4mA/W = 0.41A, and the system fails. - While the resistive load is cycled on, the input power is 570W. The 3rd harmonic current must be less than 570W * 3.4mA/W = 1.94A. The system passes. Any suggestions? Thanks,
