For example: An excerpt presented by the San Francisco Maritime National Park Association illustrates the types of overspeed systems with governor and engine control.
[4] It trips off the engine by cutting off fuel injection by having the centrifugal force act on levers linked to the governor collar.
[6] In turbines and many other mechanical devices used for power generation, it is critical that the response times for overspeed prevention systems be as precise as possible.
[7] If the response is off by even a fraction of a second, it can lead to turbines and its driven load (i.e. compressor, generator, pump, etc..) suffering catastrophic damage, and can put people at risk.
[7] Because the contact with the lever occurs over a relatively limited angle, there is a maximum trip response time of 15 ms (i.e. 0.015 sec).
[7] Electrical overspeed systems on turbines rely on a multitude of probes that sense speed through measuring the passages of the teeth of a spur gear.
When configuring, testing, and running any overspeed systems on turbines or diesel engines, one factor considered is timing.
However, variability is always present, and it is important for the owner/operator to understand the system in the event of maintenance, replacement, or retrofitting of outdated or worn out parts.