According to the layout of the high-voltage circuit in the whole vehicle, it will be suspended under the chassis of the car. It is a principle that the high-voltage cannot enter the cabin. Therefore, most high-voltage connectors will be located in the chassis near the ground or near the hub. When some When the weather is bad, such as severe weather, heavy rain or some severe cold weather, the water from your tires will actually impact these connectors. If you are familiar with the test, there is no IP6K9K in the domestic standard, you will It is found that if the IP67 is used, the impact pressure of the high-pressure water gun is actually not as large as 6k9k. When the car is running at high speed and suddenly wading into the water, the instantaneous water pressure to the connector will be very large, so IP67 is sometimes difficult to meet the actual use requirements. In view of this, the domestic standard QC/T1067 and the foreign standard USCAR divide the connector seal into two grades S1 and S2. For the S2 level, it is clearly stipulated that the applicable occasion is the lower position of the chassis, and 6K and 9K are recommended, so 6K and 9K must be used for future connection protection. If the connector is not arranged in the above position, the design of IP67 can still meet the requirements of the whole vehicle.