A system for transferring electric energy to a vehicle (81; 92), wherein - the system comprises an electric conductor arrangement for producing an alternating electromagnetic field and for thereby transferring the energy to the vehicle (81; 92), - the electric conductor arrangement comprises a plurality of lines (1, 2, 3) for carrying in each case one phase of an alternating electric current, - the lines (1, 2, 3) extend along the track, - each line (1, 2, 3) is arranged in such a manner that it produces - at each point in time while the alternating electric current is flowing through the line (1, 2, 3) - a row of successive magnetic poles of an electromagnetic field, wherein the successive magnetic poles have alternating magnetic polarities, - the row of successive magnetic poles extends in the travel direction of the vehicle (81; 92) which is defined by the track, - each line (1, 2, 3) is adapted to carry one phase of a multi-phase alternating voltage or current, wherein the magnetic poles produced by the lines (1, 2, 3) are - at each point in time - in a repeating sequence extending in the travel direction, wherein the repeating sequence corresponds to a sequence of the phases, characterized in that - the lines (1, 2, 3) are combined with a constant-current source, which is adapted to feed the lines (1, 2, 3) with an alternating current having a constant mean value independently of the power which is transferred from the electric conductor arrangement to the vehicle (81; 92) or vehicles on the track, - the constant-current source comprises an arrangement for transforming an alternating voltage of an energy source into an alternating current, the arrangement comprising - in each line (1, 2, 3) - an input inductance (L1a, L2a, L3a) at an input side of the constant-current source and an output inductance (L1b, L2b, L3b) at an output side of the constant-current source, wherein the input side is connected to the energy source, wherein the output side is connected to line sections of the lines (1, 2, 3) along the track, wherein each of the lines (1, 2, 3) comprises a connection point between the input side and the output side and wherein each connection point is connected to a common same star point via a capacitance (C1, C2, C3).. - the system comprises an electric conductor arrangement for producing an alternating electromagnetic field and for thereby transferring the energy to the vehicle (81; 92), - the electric conductor arrangement comprises a plurality of lines (1, 2, 3) for carrying in each case one phase of an alternating electric current, - the lines (1, 2, 3) extend along the track, - each line (1, 2, 3) is arranged in such a manner that it produces - at each point in time while the alternating electric current is flowing through the line (1, 2, 3) - a row of successive magnetic poles of an electromagnetic field, wherein the successive magnetic poles have alternating magnetic polarities, - the row of successive magnetic poles extends in the travel direction of the vehicle (81; 92) which is defined by the track, - each line (1, 2, 3) is adapted to carry one phase of a multi-phase alternating voltage or current, wherein the magnetic poles produced by the lines (1, 2, 3) are - at each point in time - in a repeating sequence extending in the travel direction, wherein the repeating sequence corresponds to a sequence of the phases, - the lines (1, 2, 3) are combined with a constant-current source, which is adapted to feed the lines (1, 2, 3) with an alternating current having a constant mean value independently of the power which is transferred from the electric conductor arrangement to the vehicle (81; 92) or vehicles on the track, - the constant-current source comprises an arrangement for transforming an alternating voltage of an energy source into an alternating current, the arrangement comprising - in each line (1, 2, 3) - an input inductance (L1a, L2a, L3a) at an input side of the constant-current source and an output inductance (L1b, L2b, L3b) at an output side of the constant-current source, wherein the input side is connected to the energy source, wherein the output side is connected to line sections of the lines (1, 2, 3) along the track, wherein each of the lines (1, 2, 3) comprises a connection point between the input side and the output side and wherein each connection point is connected to a common same star point via a capacitance (C1, C2, C3)..