FIELD: transport engineering; trolley buses supplied by circuits with grounded negative wire. SUBSTANCE: proposed device uses for its operation principle of compensation of potential on trolley bus body by means of dc source whose voltage is changed so as to keep it equal to varying potential of body all the time. EFFECT: improved safety of passengers provided by reduced to minimum the currents through human body at getting in and out of vehicle, reduced cost of checking and time taken for checking the vehicle before getting to work. 2 dwg
