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 A disconnect switch. | |
| Component type | Switch |
|---|---|
| Electronic symbol | |
.svg) | |
Aninertial switch is aswitch, firmly mounted upon a vehicle or other mobile device, that triggers in the event of shock or vibration. It is a part ofelectrical circuits that may either enable or disable some function.[1]
The switch shown to the right is intended to disable an electricfuel pump in automotive applications. This functionality is required in somevehicle racing applications, since an electric fuel pump may otherwise continue operating after acollision orrollover. If the fuel line is broken or the vehicle is inverted, fuel may be spilled, creating a fire hazard. A small loose weight (called a proofmass) is trapped within a spring-loaded cage. A shock in any direction will cause movement of the mass relative to the cage. If sufficiently shocked, the cage will spring open which actuates an associated switch. The switch is reset by pressing the cage closed through the flexible (red) top cover, retrapping the mass. These switches are also used to open a contactor (a largerelay) to disable the high power circuit of abattery electric vehicle upon collision.
A normally open switch is used to activate passenger safety equipment early in a collision, typically to pre-tensionseat belts and/or to activateairbags to protect the occupant(s) from collision with the vehicle interior or thesteering wheel.
Inertia switches are also used inordnance applications for both safety (shell will not explode until it has been subjected to launch acceleration) and fuzing.
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