Snap-Action Mechanism in Electrical Switches
With a snap-action mechanism, the contacts will instantaneously switch at a specific stroke position without relation to the switch operating speed or operating force.
As opposed to a snap-action mechanism, with a slow-action mechanism, the operating speed of the switch is always the travel speed of the contacts.
1. Principles of snap-action mechanisms in electrical switches
If you press down on the top of a sheet of plastic that is bent info an arc, the sheet will suddenly reverse to a U shape at a certain point. This is like a snap-action mechanism.
2. Features of snap-action mechanisms in electrical switches
- Because the contacts switch at high speed, any arc between the contacts will not continue for a long period of time. This reduces contact wear and maintains contact reliability.
- Even miniature switches can make and break large currents.
- With AC, the current flow alternates, so arcs are cut off more easily at the same voltage and current in comparison with DC. Therefore, contact damage is less with AC.
When pressure is applied to the pushbutton of a switch, the force of the movable spring causes the moving contact to quickly switch from the NC fixed contact to the NO fixed contact.
When pressure is released from the pushbutton of a switch, the force of the movable spring causes the moving contact to quickly switch from the NO fixed contact to the NC fixed contact.