What are the different sorts of connectors (plugs and sockets)?

Industrial power connectors are colour coded as follows:

Red for 3-phase 380-415V
Blue for single phase 220-240V
Yellow for single phase 110-120V

3-phase connectors can have four pins (3 phases + earth) or five pins (3 phases + neutral + earth). They are supplied in several current ratings, the most used being 16A and 32A per phase. Boosters now use only 5-pin connectors rated at 16A per phase.