Why is proper grounding essential when connecting a GPU to an aircraft?

Proper grounding is essential when connecting a Ground Power Unit (GPU) to an aircraft to prevent the buildup and discharge of static electricity, as well as to provide a safe path for fault currents. Aircraft, especially when in contact with the air, can accumulate significant static electrical charges. A GPU that is not properly grounded can create a difference in electrical potential between the GPU, the aircraft, and the surrounding environment. This difference can lead to a sudden, uncontrolled discharge of static electricity, which can damage sensitive electronic equipment on board the aircraft, pose a fire hazard, and potentially injure personnel. Furthermore, grounding provides a low-resistance path for fault currents, which are unintended electrical currents that can occur due to insulation failure or equipment malfunction. If a fault current occurs in a properly grounded system, the current will flow safely to ground, tripping circuit breakers or fuses and isolating the faulty equipment. Without proper grounding, fault currents can flow through unintended paths, potentially causing electrical shock or equipment damage. Therefore, a reliable grounding connection is a critical safety measure when using a GPU to power an aircraft.