A multi-phase electric drive, including: a multi-phase power transformer, including at least one primary winding and a first number of secondary windings, said primary winding being electrically connectable to a source of multi-phase AC power; a first number of power units, each of said first number of power units having input connected with a corresponding one of said first number of secondary windings, and a multiple of said first number of power units being serially connected with respective others of said power units in each phase output line connectable to a multi-phase AC load; characterized in that the multi-phase electric drive further includes: at least two measurement devices (24, 320-324), being respectively electrically connected with said inputs to at least two of said first number of power units and being adapted for measuring an electrical quantity at the input thereto; and a control system, being adapted for detecting a fault based on a value for the measured electrical quantity; wherein said control system is further adapted for detecting said fault based on difference between the values for said electrical quantities measured at said inputs to said at least two power units, wherein: said control system is further adapted for detecting said fault based on the value for the electrical quantity measured at the input to one of said at least two of said first number of power units and an average of the values for said electrical quantities measured at the inputs to said at least two of said first number of power units; wherein further: said control system includes a main controller and at least two power unit controllers; the main controller is adapted for calculating said average; and said power unit controller is adapted for detecting said fault based on said average and the value for the measured electrical quantity. a multi-phase power transformer, including at least one primary winding and a first number of secondary windings, said primary winding being electrically connectable to a source of multi-phase AC power; a first number of power units, each of said first number of power units having input connected with a corresponding one of said first number of secondary windings, and a multiple of said first number of power units being serially connected with respective others of said power units in each phase output line connectable to a multi-phase AC load; characterized in that the multi-phase electric drive further includes: at least two measurement devices (24, 320-324), being respectively electrically connected with said inputs to at least two of said first number of power units and being adapted for measuring an electrical quantity at the input thereto; and a control system, being adapted for detecting a fault based on a value for the measured electrical quantity; wherein said control system is further adapted for detecting said fault based on difference between the values for said electrical quantities measured at said inputs to said at least two power units, wherein: said control system is further adapted for detecting said fault based on the value for the electrical quantity measured at the input to one of said at least two of said first number of power units and an average of the values for said electrical quantities measured at the inputs to said at least two of said first number of power units; wherein further: said control system includes a main controller and at least two power unit controllers; the main controller is adapted for calculating said average; and said power unit controller is adapted for detecting said fault based on said average and the value for the measured electrical quantity. at least two measurement devices (24, 320-324), being respectively electrically connected with said inputs to at least two of said first number of power units and being adapted for measuring an electrical quantity at the input thereto; and a control system, being adapted for detecting a fault based on a value for the measured electrical quantity; wherein said control system is further adapted for detecting said fault based on difference between the values for said electrical quantities measured at said inputs to said at least two power units, wherein: said control system is further adapted for detecting said fault based on the value for the electrical quantity measured at the input to one of said at least two of said first number of power units and an average of the values for said electrical quantities measured at the inputs to said at least two of said first number of power units; wherein further: said control system includes a main controller and at least two power unit controllers; the main controller is adapted for calculating said average; and said power unit controller is adapted for detecting said fault based on said average and the value for the measured electrical quantity. said control system includes a main controller and at least two power unit controllers; the main controller is adapted for calculating said average; and said power unit controller is adapted for detecting said fault based on said average and the value for the measured electrical quantity.