IEC 62196-3 defines the dimensional compatibility and interchangeability requirements for the d.c. and combined a.c./d.c. pin and contact-tube vehicle couplers used for the conductive charging of electric vehicles. It performs for direct current charging the same function that the preceding part performs for alternating current: it fixes the geometry of the coupler so that any connector of a given configuration will mate with any inlet of the same configuration, which is the necessary condition for a public charging network to serve vehicles of different manufacturers. The standard specifies the dimensions and arrangement of the power contacts, which for d.c. charging must carry high currents, together with the signal and control contacts and the keying features that distinguish the d.c. configurations from one another and from the a.c. accessories. It describes the coupler configurations in use, including the combined system in which a d.c. extension is added to an a.c. connector, and it references the gauge and endurance tests of the general part for verification.