At what speed should the governor switch contact be set to open?

The governor switch contact is typically set to open at a speed that allows for effective control and response to changes in the operational speed of an engine or turbine. Setting the contact to open at 90-95% of the governor tripping speed strikes a balance between maintaining optimal performance and ensuring safety. This range allows the system to react in time to prevent over-speed conditions, which can lead to mechanical failures or accidents.

By setting the governor switch at this percentage, it allows for a safety buffer, ensuring that even if the system experiences a slight spike in speed, it will still remain within controlled parameters. This setting helps the governor to regulate the speed effectively, reducing the risk of overshooting the tripping speed, which is critical in safeguarding the machinery and enhancing operational efficiency.