Key Switches & Selector Switches
How do key switches work, and what are the main differences between them?
Key switches or lock switches include a range of switch types that can only be actuated when used simultaneously with a physical key. This helps prevent unauthorised access to (or accidental triggering of) whichever system, machinery or process is controlled by the key switch actuator mechanism.
Key switches are widely used in processes such as automation control, comms systems, fire and security alarm panels, power distribution, and automatic door controls. Important factors to consider when buying key switches online include:
- Number of positions - this can typically range anywhere between 1-6 positions, giving you full control over how many different states and potential functions the key switch is able to differentiate between as it’s turned.
- Switch operation - common types of key switch operation include latching, momentary, maintained, snap action, and spring return. These operations can be used to control various lock switch function arrays such as off-on, on-off-start, break before make, and acc-off-ign.
- Contact configuration - controls how the key switch behaves at various positions when turned, with common examples including Single Throw (ST), Single Pole Double Throw (SPDT), and Double Pole Double Throw (DPDT).
- Key trapping - whether or not the key must be retained in the lock switch once actuated, in order for the relevant circuit to remain open/closed.
- IP ratings - the level of protection you require against ingress of dirt/moisture around the key switch housing, dependent on environmental conditions.
- Key switch covers and key types - caps, covers and bezels can all improve security or ease of access to key switch modules, while key types can range from simple fish keys to fully toothed and cut spares for various lock switch series and standards.