Abstract: By analyzing the relationship between the discharge capacity of the capacitor, the discharge of the capacitor and the threshold of perception and the threshold of pain, understand the 22.5 of GB 4706.1-2005 "there is no risk of electric shock from charged capacitors having a rated capacitance exceeding 0.1μF ", and analyzing the cause of one second after disconnection, the plug voltage value should not exceed 34V. In addition to the standard requirements, to carry out voltage of plug measurement methods to discuss, help the laboratory testing engineers to understand the standard, master the correct detection method.

Key words: Plug discharge, Discharge capacity, Peak power off, Measuring probe, Coupling method