PORTABLE POWER SUPPLY SYSTEM FOR AN ELECTRICALLY DRIVEN WORK MACHINE AND A WORK MACHINE EQUIPPED WITH SUCH A POWER SUPPLY SYSTEM

A portable power supply system supplies a remotely controlled, electrically driven work machine with electrical power. The work machine includes continuous tracks and is equipped with a maneuverable arm that carries a tool at its free end. An electric motor is connected to a hydraulic pump and supplies the machine with a hydraulic medium. The work machine is connected under normal operation to a primary source of power via an electrical cable. The primary source of power includes a fixed alternating current electricity distribution grid at the location. In order to be able to supply the current that is required it includes a DC energy-storage arrangement that, including a secondary source of power, can store energy and, when necessary, supply energy in electrical form. A coupling arrangement makes it possible to choose between connecting the motor to the primary or the secondary source of power.