Static Air Gap Tool Measures Critical Aspect of Hydro-Generator Operation

The Kaman AGT significantly reduces the number of overhaul technician hours.

Kaman Measuring

Kaman Precision Products (Colorado Springs, CO) announced the Static Air Gap Tool (AGT), a portable measurement device that helps reduce downtime by measuring the installed static air gap between the generator rotor and stator.

To operate, insert the device into the air gap to display and record measurement data.


  • Reduction in overhaul technician hours of 90%
  • Developed to make static measurement electronically by sliding spring end of robust measurement paddle into gap between rotor and stator
  • Eddy current sensor coil located between springs that measures compression of springs to match gap
  • Compression springs wide enough to account for variability in different rotor and stator windings
  • Signal conditioning electronics at handle end of paddle that translate inductance change in sensor coil to distance and wirelessly transmit to operator’s handheld device
  • Can be used in any orientation, horizontally or vertically depending on the design of the generator
  • Powered by a long-life rechargeable battery that permits up to eight hours of operation between charges
  • Adjustable wedges in middle to provide consistent insertion depth if rotor and stator design permit
  • Measured distances displayed and stored in app available for iOS and Android devices

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