Iris Power RFAII-R

Periodic Online Rotor Magnetic Flux Analyzer

The RFAII-R is portable instrument to collect and analyze magnetic flux data from any flux probe in real time, providing the user with data on rotor winding shorted turns.

Turbine Generator
Works with These Assets


Data Acquisition

  • Ideally used with permanently installed Iris Power Total Flux Probe (TFProbe) or Folding Flux Probe (FFProbe)
  • Inputs for shaft sync sensor (Keyphasor) for pole determination when shorts are detected.
  • Custom built, ultra-high resolution digital data acquisition module, including on-board switchable attenuation for maximum resolution  measurements using virtually any flux probe
  • High speed acquisition capability creates a table of results covering each pole and each load point

Data Analysis

  • The RFAII and RotorFluxPro software provides instant analysis to indicate the presence and location any rotor poles with shorted turns .

  • Analyzing the voltage waveforms in real time, comparing average and discrete flux readings, and trending readings to identify anomalies in the flux due to shorted turns.


  • Rugged portable instrument connects to a control computer using USB and Ethernet interfaces

Group Created with Sketch. Applications

  • The condition of the rotor winding insulation is difficult to assess during minor or major generator maintenance outages. Access to the winding is severely restricted without removal of the retaining rings and of the winding wedges. The off-line tests for detection of shorted turns and ground fault locations can also be frustratingly ineffective due to the frequently intermittent nature of faults at speed and at standstill. Therefore, on-line measurements are much preferred to off-line tests and inspections.
  • On-line measurements require the permanent installation of a flux probe on the stator to measure the slot leakage flux. Qualitrol-Iris Power makes  two kinds of flux probes. The first is a foldable  probe called the FFProbe™ which is attached to a stator winding wedge protruding into the airgap. We also offers an alternative probe, the Iris Power TFProbe™,  which is a small, thin, flexible, printed circuit board transducer affixed to a tooth of the stator. It is designed for generator airgap <50mm. The Iris Power TFProbe measures the total airgap flux, rather than just the leakage flux. The Iris Power TFProbe is easy to install. Frequently, it can be installed with the rotor still in place! In the case of hydrogen-cooled machines, the leads from the flux probe are routed out of the machine through a hermetically sealed feed-through.
  • Regardless of the probe technology, data from permanently installed flux probes can be measured via software, with the Iris Power RFAII-R, or continuous on-line monitors like the Iris Power FluxTracII™. Once the data are acquired, analysis techniques must be applied to compare the flux measurements across various rotor slots to determine if the turn shorts are present.