The voltage and current levels of pure electric vehicles are relatively high. The power voltage is generally 300-400 V (DC), and the current can reach hundreds of amperes in an instant. The safe voltage value that the human body can withstand depends on the current allowed by the human body and the resistance of the human body. Relevant studies have shown that the resistance of the human body is generally between 1000 and 3000 Ω. Human skin resistance is related to the state of the skin. It can be as high as tens of kiloohms when it is dry, clean and undamaged, but it may drop below 1000 ohms for wet skin, especially when it is manipulated. Since the safety voltage in our country is mostly 36 V, it is roughly equivalent to the situation where the allowable current of the human body is 30 mA and the resistance of the human body is 1200 Ω. Therefore, it is required that the voltage of any two live parts of the electric vehicle accessible to the human body should be less than 36 V. According to the requirements of the International Electrotechnical Standards, the safety threshold of electric current that the human body does not have any feeling is 2 mA, which requires that when the human body directly contacts any part of the electrical system, the current flowing through the human body should be less than 2 mA before the vehicle insulation is considered qualified.
Therefore, in the development process of pure electric vehicles, special consideration should be given to the insulation of the electrical system, and the design should be strictly in accordance with the requirements of relevant national standards for electric vehicles to ensure that the insulation resistance can meet the needs of personal safety and ensure that the insulation resistance value is greater than 100 Ω/V.