GPU for the provision of electrical energy for aircraft

A ground power unit provides electrical energy for aircraft and a method maintains and operates the ground power unit. The ground power unit includes a base frame, a cable system formed in the base frame, at least one rectifier module for converting an input alternating voltage applied to a rectifier module input side into an intermediate direct voltage output at a rectifier module output side, wherein the rectifier module output side is coupled to an intermediate circuit conductor and at least one inverter module for converting the intermediate direct voltage applied to an inverter module input side into an output alternating current output at an inverter module output side, wherein the inverter module input side is coupled to an intermediate circuit conductor. The rectifier module and the inverter module are each realized as structurally-independent units, which can be replaced individually and independently of the base frame.