This microswitch is actuated by a tooling registration pin coming down through the probe plate when the functional test fixture’s gate is closed. This contact closure can be used by the test system to initiating a test or to apply power to the device under test.
![Gate-closed Microswitch](https://www.testhead.com/wp-content/uploads/2020/02/Gate-Closed-Microswitch-1024x768.jpg)