An arrangement for electrically powering an aircraft comprises at least one first generator driven by an engine of the aircraft, an electricity network on board the aircraft receiving the voltage produced by the first generator, at least one second generator driven by the motor, and an engine electrical network distinct from the on-board network for powering equipment of the engine of its environment, the engine network comprising: at least one DC electrical voltage distribution bus for the electrical equipment; and a power supply circuit having a first input connected to the on-board network, a second input connected to the second generator to receive the electrical voltage supplied thereby, a voltage converter connected to the second input, and a selector circuit for delivering a voltage on the distribution bus, the voltage being supplied from that received on the first input or from that supplied by the converter depending on the amplitude of the voltage supplied by the second electricity generator.