Plug, plug receptacle and electric power supplying system

A plug comprising:

• at least two electrodes;
• a housing that supports the electrodes;
• an electrode cover which covers the electrodes when not inserted in a plug receptacle, and which is accommodated in the housing by the plug receptacle and exposes the electrodes when inserted in the plug receptacle;
• and
• a lock mechanism which inhibits the electrode cover from being accommodated in the housing when not inserted in the plug receptacle, and which allows the electrode cover to be accommodated in the housing when inserted into the plug receptacle.

An electric power supplying system comprising:

• a bus line which is formed by at least two conductors and on which an information signal representing information is superimposed on electric power;
• at least one power supply server which is connected to the bus line and which supplies the electric power;
• and
• at least one client which is connected to the bus line and which receives the supply of the electric power from the power supply server,
• wherein at least one of the power supply server and the client is provided with a plug that includes
• at least two electrodes,
• a housing that supports the electrodes,
• an electrode cover which covers the electrodes when not inserted in a plug receptacle and which is accommodated in the housing and exposes the electrodes when inserted in the plug receptacle, and
• a lock mechanism which inhibits the electrode cover from being accommodated in the housing when not inserted in the plug receptacle, and which allows the electrode cover to be accommodated in the housing when inserted into the plug receptacle, and
• wherein the bus line is provided with the plug receptacle that includes
• a cover that protects electrodes and
• a lock release mechanism that, when the plug is inserted, releases the inhibition, by the lock mechanism, of accommodation of the electrode cover into the housing.