Inertia Shut Off Switch - Fuel Pump - WQT100030
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An inertia shut off switch: a mechanical impact sensor that latches open when the vehicle takes a sharp enough deceleration. Originally a fuel pump cut off, and exactly the right part for cutting a high voltage enable in a conversion.
What it does is decide, mechanically, that a crash has happened. A sprung mass inside the switch holds a contact closed. A sufficient impact throws that mass off its seat and the contact latches open and stays open until somebody presses the reset button on top. No power, no electronics, no software, and no way for it to be talked out of the decision.
In a petrol car it stops the fuel pump after an accident. The reasoning transfers directly: in a converted car the thing you want to stop is the contactors. Wire this switch into the contactor enable or the interlock chain and an impact drops the pack out and leaves it out, whatever the rest of the vehicle thinks.
It latches, which is the whole point. A momentary sensor that resets itself lets a damaged vehicle re energise. This one has to be reset by hand, deliberately, by someone who has looked at the car.
Key specifications
| Part | WQT100030 |
|---|---|
| Type | Inertia shut off switch |
| Action | Latches open on impact, manual reset |
| Operation | Mechanical, requires no power |
| Original application | Fuel pump cut off |
| Weight | 0.01 kg |
Features
- Purely mechanical, so it works with the vehicle electrically dead
- Latches open and stays open until reset by hand
- Manual reset button on the body
- Proven automotive part rather than an improvised sensor
Compatibility
For fuel pump cut off in its original application, and for contactor enable or interlock duty in an EV conversion.
Mount it rigidly and the right way up. An inertia switch senses along a defined axis and relies on being solidly attached to the structure. Bolted to a flexible panel, or mounted at an angle, it will either trip over a pothole or fail to trip in an accident. Both are bad, and one of them is dangerous.
Switch a signal with it, not a load. Put it in the enable line to your contactor controller rather than in series with a contactor coil, so it interrupts a small current and the controller does the switching.
Ask us for the contact rating and the mounting orientation before you design it in. Only photographs are published for this part, and those are the two things you need.
In the box
- 1 x inertia shut off switch
Downloads
Only product photographs are published for this switch. Contact us for the contact rating, the trip threshold and the correct mounting orientation.