The ornamental design for a multi-voltage electrical transformer, as shown and described.
FIG. 1 is a perspective view of a multi-voltage electrical transformer showing my new design;
FIG. 2 is a perspective view thereof, shown in an open condition;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The portions of the claim shown in broken lines form no part of the claimed design. The broken lines immediately adjacent to the claimed areas in the views represent boundaries of the design. None of the broken lines form any part of the claimed design.