Service Box

Within the service box, three Power Contactors play a pivotal role in enabling traction voltage for the entire installation. The Pre-charge contactor is responsible for gradually pre-charging the system to nominal voltage through a 10kOhm power resistor before allowing the full power connection from the battery pack.

Function:

The positive and negative traction voltage cables originating from the battery, marked as IN, remain live as long as the 250A main fuse on the battery is installed. However, both the positive and negative cables going out from the service box, marked as OUT, remain inactive until the contactors are activated, and the traction voltage system becomes live.

One of the most prevalent issues related to traction voltage involves contactor damage due to unexpected disconnection while in use, posing a safety risk. This can occur, for instance, when the emergency stop switch is pressed or the High Voltage Interlock Loop (HVIL) circuit is disconnected.

Safety:

The Service Box (SB) is specifically designed for EV technicians to verify the absence of traction voltage and inspect the contactors. To access the traction voltage contactors, it is necessary to remove the service box lid.

When working with the live part of the traction voltage, it is crucial to prioritize safety. Therefore, the Potential Equalization (PE) cable should be removed LAST and installed FIRST. This ensures a secure working environment when dealing with the active components of the traction voltage system.

By understanding the functions and features of the Service Box, users can effectively understand, operate, and maintain the Electric Vehicle Onboard Service Box, fostering a reliable and safe integration of their electric vehicle with external charging infrastructure and service operations.