Power supply unit with replaceable plug

A power supply unit having replaceable and orientation adjustable plug, comprising:

• a main body having a substantially regular polygon-shaped plug mounting seat having enclosing retaining walls that define a receiving region, wherein at least one guide rail and two conducting elements are arranged on the main body in the receiving region, wherein a plurality of engagement blocks are arranged within the periphery of the receiving region opposite to each other, wherein an engagement slot is formed on each engagement block;
• a plug, comprising
• a base;
• at least two pins protrudingly arranged on a front surface of the base;
• a plurality of first contact pieces and a plurality of second contact pieces arranged on a rear surface of the base and connected to the respective pins;
• at least a pair of fixing blocks arranged on the rear surface of the base;
• at least a pair of stoppers arranged on the rear surface of the base, wherein a fixing portion is formed on the free end of each stopper;
• and
• a plurality of guide slots formed on the rear surface of the base;
• wherein the plug is removably received in the plug mounting seat, wherein each guide slot thereof pairs with one of the at least one guide rail,
• wherein the fixing portions of the plug are received by the corresponding engagement slots for securing the plug to the main body, and
• wherein the conducting elements of the main body abut to the corresponding first contact pieces and the second contact pieces of the plug for establishing electrical connection.