IEC 60309 is the international standard which covers plugs, sockets & couplers designated for industrial purposes. The come with an integrated 'locking' mechanism which holds the connectors together, and comes with an IP rating of either IP44 (splashproof) or IP67 (waterproof).
The standard allows for different connectors to suit most countries and voltage/frequency systems. For identification of the appropriate connector, there is firstly there is a colour code system, and secondly a 'key' system.
The key is a plastic notch which is located at various 'clock positions' around the outside of the connector. In Australia, our connectors are "Blue" (for single phase, 3 pin) and "Red" (for three phase, 4 & 5pin), and our 'clock position' is "6H" or, with the earth pin at the bottom of the connector (always 6 o'clock), the 'key' is at 6-Hour, or 'six o clock' [so for Australia the "key" is always next to the earth pin]. The 'Key' stops any accidental insertion of a plug into the incorrect socket/coupler.
This connector is not as common in installations in Australia as the Captive/Clipsal connector has dominated the industry, however there are some sites which have been regularly importing equipment from overseas and so have installed the appropriate socket-outlet on site for ease of installation.
We can support these sites by installing the appropriate connector on the PDU during the manufacturing process, and by providing adaptor cables where safe and appropriate.