This panel mounting key switch is of the momentary action type, i.e. it closes the circuit when operated, but springs back to the off position when released.
To operate, push in the key (it's spring loaded, so the key pops out by 5mm when released) and turn about 60 degrees clockwise. This makes the circuit, i.e. it turns on for a long as the key is held in that position.
As soon as the key is released, the circuit is broken (turns off) and the key rotates back to its original position, and pops out by 5mm.
This key switch was designed for use with PCs, for the power-on function. Normally, a PC (personal computer) is powered on by pressing a button momentarily. Sometimes it's desirable for the power-on function to be more secure, and this key operated switch is ideal for this purpose.
Of course, you can use this switch for any other purpose.
It can be fitted into a round hole in a panel, but ideally the hole should have flats as shown in the image above, so that the barrel cannot rotate.
All the keys of this product are the same.
These switches are not marked with a current or voltage rating but they were designed to replace the low-voltage start button on PCs, i.e. 5VDC with just a few milliamps. They are best suited to TTL levels, i.e. 5VDC +/- 0.25 VDC, at around 40-50mA.
They are not suitable for AC voltages or heavy current. However, they can be used to trigger a heavy current mains relay, provided that the relay can be controlled by a low voltage low current switch. Note, however, that the switch action is momentary, so unless the relay is of a latching type, the relay will be activated only for as long as the key is turned.
Dimensions:
Hole size: 19.5mm to 20.5mm
Barrel diameter: 18.9mm
Barrel size across flats: 16.8mm
Bezel diameter: 22mm
Bezel height: 6.3mm
Barrel length: 31.7mm
Overall distance from underside of bezel to terminals: 40mm approx
Nut diameter across flats: 22.2mm
Nut diameter across corners: 25mm
Cable length: 60mm
2-pin connector
Pin spacing: 2.54mm
Connector dimensions: 5 x 2.5 x 14.5 mm