How does a Murphy switch work?

Answer 1

Murphy switches monitor various parameters such as temperature, fluid level, vibration, water pressure, etc. They shut down engines, motors, etc., if there is deviation from the desirable operating range of the monitored parameter. Other Murphy switches will actually vary throttle on engines to maintain a desired parameter within acceptable limits.

They generally work by disrupting an electrical circuit or other vital function, causing the motor or engine to shut down.

For instance, I farm and have Murphy switches for irrigation pumps, booster pumps, fertigation pumps, and pivots. Basically, if one system fails, then all of the other components will shut down, to prevent wasting irrigation water and energy and to prevent damage to various components of the system.

On my natural gas motors, I have Murphy switches which will shut down the motor if the oil level gets low, the temperature gets too high, or if the water pressure from the irrigation pump gets too high or low.

Answer 2

A "murphy switch" is an electrical switch that is commonly used in industrial applications. They are designed to protect an engine or component during certain types of mechanical failures. An example could be; if the machine's engine loses internal oil pressure the switch would electronically disconnect the engines fuel supply and shut it down. They could also be used to sense excessive coolant temperature and do the same. The switches are designed and manufactured by Frank W. Murphy MFR. of Tulsa, OK.