A power supply appliance of a transport system, which power supply appliance comprises a frequency converter of a motor, - an AC voltage circuit to supply power to an electrification of the transport system, a power supply circuit of safety devices of the transport system, as well as a power shaping circuit fitted between a DC intermediate circuit of the frequency converter of the motor, the AC voltage circuit and the power supply circuit of the safety devices, which power shaping circuit comprises: a first and a second change-over switch (24, 25) fitted as an H-bridge in the DC intermediate circuit of the frequency converter of the motor, - as well as diodes fitted as an antiparallel circuit in parallel with negative and the positive changeover contacts (26, 27) of the change-over switches (24,25), characterized in that the power shaping circuit further comprises a transformer comprising a plurality of windings, of which a first winding is fitted to the H-bridge between the center points of the first and the second change-over switch, a second winding is fitted to the AC voltage circuit and a third winding is fitted to the power supply circuit of the safety devices, as well as - a control of the H-Bridge, whereby the power shaping circuit is configured to supply during normal operation of the transport system power from the DC intermediate circuit of the frequency converter to the power supply circuit of the safety devices as well as to the AC voltage circuit, whereas if a mains voltage supply terminates or the mains voltage decreases for some reasons so much that the formation of sufficient control voltage for the motor or for the frequency converter is no longer possible or the amplitude of the fundamental wave of the voltage of the AC voltage circuit no longer remains constant, the control of the H-bridge of the power shaping circuit is configured to control the change-over switches (24, 25) into a non-conductive state and to send a control command via a communication channel to an inverter, on the basis of which control command the inverter is configured to start supplying power from a second energy storage to a fourth winding of the transformer of the power shaping circuit and, via the transformer, onwards to the DC intermediate circuit of the frequency converter, as well as to the power supply circuit of the safety devices and to the AC voltage circuit. - an AC voltage circuit to supply power to an electrification of the transport system, a power supply circuit of safety devices of the transport system, a first and a second change-over switch (24, 25) fitted as an H-bridge in the DC intermediate circuit of the frequency converter of the motor, - as well as diodes fitted as an antiparallel circuit in parallel with negative and the positive changeover contacts (26, 27) of the change-over switches (24,25), characterized in that the power shaping circuit further comprises a transformer comprising a plurality of windings, of which a first winding is fitted to the H-bridge between the center points of the first and the second change-over switch, a second winding is fitted to the AC voltage circuit and a third winding is fitted to the power supply circuit of the safety devices, as well as - a control of the H-Bridge, - as well as diodes fitted as an antiparallel circuit in parallel with negative and the positive changeover contacts (26, 27) of the change-over switches (24,25), characterized in that the power shaping circuit further comprises a transformer comprising a plurality of windings, of which a first winding is fitted to the H-bridge between the center points of the first and the second change-over switch, a second winding is fitted to the AC voltage circuit and a third winding is fitted to the power supply circuit of the safety devices, as well as - a control of the H-Bridge, whereby the power shaping circuit is configured to supply during normal operation of the transport system power from the DC intermediate circuit of the frequency converter to the power supply circuit of the safety devices as well as to the AC voltage circuit, whereas if a mains voltage supply terminates or the mains voltage decreases for some reasons so much that the formation of sufficient control voltage for the motor or for the frequency converter is no longer possible or the amplitude of the fundamental wave of the voltage of the AC voltage circuit no longer remains constant, the control of the H-bridge of the power shaping circuit is configured to control the change-over switches (24, 25) into a non-conductive state and to send a control command via a communication channel to an inverter, on the basis of which control command the inverter is configured to start supplying power from a second energy storage to a fourth winding of the transformer of the power shaping circuit and, via the transformer, onwards to the DC intermediate circuit of the frequency converter, as well as to the power supply circuit of the safety devices and to the AC voltage circuit.