Test Circuit Analysis and Evaluation of 400 VDC Appliance Coupler

We attempted to evaluate a 400 VDC appliance coupler by performing a test with the inrush current and test circuit defined in IEC TS 62735-1, an international standard covering plugs and socket-outlets for 400 VDC appliance couplers published in 2015 [1]. However, we were unable to obtain the specified inrush current waveform with a test circuit constructed according to the specification. We identified problems in the specified test circuit and analytically determined a method for approximating the specified inrush current waveform with an actual test circuit. Specifically, we used circuit simulator to reproduce the parasitic capacitance and equivalent series resistance of the circuit wiring and components and analyzed their parameter sensitivity. The result was a more accurate reproduction of the specified inrush current waveform with an actual test circuit that produced good results when used to test a 400 VDC appliance coupler.