Electronic Speed Switches
Electronic Speed Switches


  • Models for overspeed, crank termination, or crank termination and overspeed
  • Solid state construction
  • Compact design
  • Field adjustable set points
  • High noise immunity



Murphy Electronic Speed Switches are available in various configurations to cover a wide variety of applications. These compact devices receive their input signal from various sources depending upon the particular speed switch model and application. They are available in single or dual switch point models and the switch point(s) are field adjustable.


Models are available in self-contained enclosures and as PC-board design for inclusion in your con- trol cabinet. All Murphy speed switches are designed to operate in harsh environments and have high electrical noise immunity.



  • SS300 Series: Single set point speed switch with SPDT relay dry contact output.
  • OS77D Series: Single set point speed sensing module, with a transistor output.
  • HD9063 Series: Dual set point speed switch in a pc board configuration and relay outputs.



Murphy speed switches applications include operating alarms, equipment shutdown and modulating control devices. They are ideal for disconnecting starter cranking on auto start systems or overspeed switching:

  • Generators
  • Compressors
  • Industrial Engines
  • Pumps
  • Vehicles
  • Farm Equipment
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