What is this mains connector for?

Google iec 60320 It is in use in Australia 240vac

Is the HP model number some secret or not?

That connector is commonly called an IEC connector. It can be either 120 or

If you let us know the model of the HP equipment, someone can most likely direct you to a PDF copy of the service manual with all the answers.

That socket is used on every second electronic item sold.

Been the case for 30 years too.

..... Phil

That must be one of the 2 most popular connectors on the planet. There are probably billions in Europe.

NT

Wouldn't help. These pieces of equipment are internally or externally switchable between 120 and 240V so you need to know what that switch has been set to. I think HP IIRC also used another scheme whereby you placed the appropriate fuse in the appropriate holder for the voltage of the country in question. So you would have two fuse holders, one for 120V and one for 240V and you placed your fuse - say for example 1A for 240V or 2A for 120V - in the appropriate fuse-holder. Have a look around the sides and bottom of the casing for any clues.

And here across the pond as well. I've got a few dozen of these with filtering cans on the back side culled from plasma parts before recycling.

They're great for adding to older equipment. Clean simple way of adding a ground, easily replaceable cord, and the filtering doesn't hurt either.

Sometimes you can get them with built in fuse holder too.

You can get the basic connector, but the filtered ones aren't rare - a nice touch if there's room for the filter block.

Yep, and still others have an AC switch on them..

The only place I ever saw the filtered ones were on older plasmas, which is why I saved a bunch of these when recycling the hosts.. These were big, heavy, power pigs that drew a lot of current. I believe most of filter assys were good for 20 amps.

Used to be every PC PSU - but been a while since I've seen one there.

Gunther: "HP Audio Oscillator" ????

PLEASE Be Specific, model number ? ==== HP and Office machine mfg. used a proprietary 3-pin Oval connector in 1950s and 1960s. The HP Audio Oscillators "bridged" this period --- so the connector changed -- deoendung on mfg. date. The Oval connector is sometimes identifued as AC-3G, and the plug as PH-163 There are TWO cable sets: Volex (Belden) P/N: 17280 10 B1 ; Belden P/N: 17952 (Reverse polarity, Line/Neutral swap)