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Speed Signal Generator

The Speed Signal Generator (SSG) measures the turbine rotational speed using Zero Velocity Pick-Ups. Designed to mount at the end of the generator shaft, it cancels the effects from mechanical variations (Run-out), and allows for a lift of the turbine shaft.

photo of a Speed Signal Generator


  • Measures turbine speed for speed governing, creep detection, tachometer, or overspeed protection
  • Offers high accuracy in a wide range of speeds
  • Allows creep detection per IEEE-125 standard
  • Cancels the effects of shaft run-out
  • Accommodates for turbine shaft lift
  • Available for Francis, Kaplan and Impulse Turbines


  • “Hall-effect” zero-velocity pick-ups to detect low speeds and creep detection
  • Upper and lower spring-disk design for misalignments or shaft displacements
  • Insulating barriers to isolate SSG hardware from generator base and shaft
  • Corrosion resistant enclosure to protect against contaminants
  • Heavy-duty, double-sealed, ball bearing for a long predicted life


  • Vertical and horizontal mounting engineered solutions, including mounting for a direct replacement of a Woodward PMG or SSG
  • Custom spline-shaft design available for Kaplan units
  • Up to 6 pick-ups for speed governing, creep detection, tachometer, independent overspeed protection, and installed spares


  • Output signal: 60 cycles per revolution square-wave with amplitude determined by dc supply (typically 24Vdc)
  • NEMA 12 junction box
  • Maximum allowable linear shaft displacement: +/- 0.5”
  • Typical unit weight: 57 lbs (without mounting flange)
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