Captive (AS3123) 'Clipsal 56 series'
AS/NZS 3123 describes power connectors for industrial purposes. These connectors typically have captive locking rings, and are often referred to as 'Clipsal' connectors (after the key brand on the market) or otherwise as 'Captive' plugs. The standard is based on the principles of the IEC 60309 standard, but offers scope mostly for connectors only native to Australian & New Zealand (220-240V @ 50Hz).
AS/NZS 3123 includes 10A, 15A & 20A flat pin connectors (shown above) which compliment the equivalent rated connectors in AS/NZS 3112- however there is also a range of 'round pin connectors' which do look inspired by IEC 60309 while being completely incompatible. These connectors come with an IP rating of 66.