The Importance Of Insulation Coordination For Electrical Equipment

- Jan 10, 2017-

Electric vehicle voltage and current ratings are higher, the car battery pack voltage is generally 200~600V, current up to several hundred amperes. The human body can withstand the size of the voltage depends on the safety of the human body through the current and the human body resistance. lithium battery is key element of new energy vehicle, lithium battery safety is a key problem to concern, including       

According to the national standard GB 3805 - 83 "ultra low voltage (ELV) limits" the certain voltage, by the size of the body current associated with the resistance of human body (in a shock protection device under the condition of the body allows the current to 30mA), the general resistance of the human body in a dry, no external injury condition about about 2000 ohm. So that the DC voltage is greater than 60V will have electric shock injury to the human body, the electric vehicle battery is a high voltage, and is a high energy storage device, so without any protection against electric shock situation, personnel touch will not survive.          

According to the International Electrotechnical standards, the human body without any sense threshold is 2 mA. This requires that if people or other objects to form a power battery system (or "high voltage" circuit) and the external circuit between the worst-case leakage current can not exceed 2 mA, when it is in direct contact with the people at any point of the electrical system, the current flowing through the body should be less than 2 mA vehicles qualified insulation. Therefore, in the development of electric vehicles, we should pay attention to the insulation design of high-voltage electrical system, strictly control the insulation resistance value, so that the leakage current in the safe range.