Modern vehicles have become mobile networks, connecting a variety of features and functions such as built-in controls, mobile media, and wireless networks. These vehicle-based applications, including information and entertainment systems, remote information processing, and safety controls, require the use of existing network standards, built-in control Bluetooth, and other standards.

These network applications can be physically connected via wire harnesses. The vast majority of built-in controllers, built-in or plug-in multimedia, and wireless network functions are powered directly by the vehicle's battery or powered on through the ignition switch. However, due to factors such as the electrical system itself, human interference, or load changes, more and more sensitive vehicle-based electronic devices are susceptible to damage.

When the car is started, a transient surge of 6V is generated, causing the power supply voltage to drop to 6V. When the AC generator produces charging current, the charging battery is disconnected from the AC generator, resulting in a throw-over load. Sudden changes in overvoltage can cause a 24V cross-connect starting transient, and battery reversal transients are caused by inadvertent battery reversal.

To prevent networks and connecting components from being damaged by problems such as overcurrent, overvoltage, or overheating, automobile manufacturers and component suppliers need to follow complex design specifications. These specifications include limiting overcurrent when faults or overloads occur through overcurrent protection, as well as limiting voltage spikes or being in a stable state of overvoltage through circuit protection components.