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


  • Rugged portable instrument with USB and Ethernet computer interfaces
  • Custom built, ultra-high resolution digital data acquisition and on-board switchable attenuation for maximum resolution measurements using any manufacturer’s flux probe
  • High speed acquisition with deep memory for complete and accurate data collection
  • Capable of storing over one hundred and fifty flux waveforms
  • Can be synchronized to a power frequency signal, or ideally to an external shaft sync signal (key phasor)
  • Use with 2-pole or 4-pole rotors
  • Predictions of turn-shorts in any slot, often regardless of the generator load point during data acquisition
  • A high-speed acquisition mode immediately creates a table of results covering each coil at each load point, including flux waveforms
  • Stand-alone mode where the Iris Power RFAII-R can collect data automatically as the generator goes through normal load changes
  • User friendly Windows™ based software for data display, analysis, and trending
  • Analysis software capable of reading and analyzing data files from other manufacturers’ portable instruments
  • Instant analysis of round rotor winding condition usually at any operating load
  • Where needed, ability to analyze tests at different loads for a more certain prediction of rotor winding condition
  • Able to perform a spot measurement, or automatically acquire results over days during normal generator load changes, without operator intervention
  • Works with conventional wedge-mounted flux probe, or the stator tooth-mounted Iris Power TFProbe™, which can often be retrofitted with the rotor in-place
  • Systems are available for remote and continuous monitoring
  • Optional mode for finding shorts in spin pits with the rotor operating at different speeds
  • Optional instrument that can be used with both round rotors and salient pole rotors
    • Voltage: 115/230 V, 50/60 Hz
    • Consumption: <100 W
    • USB Port (type B connector), Ethernet Port (RJ45 connector)
    • Connectors:
    • BNC for both single ended (1) or differential flux signals (2)
    • 8-pin, polarized, for integrated flux and sync sensor signal (combination probe)
    • Signal range: 0.3 V to 48 V
    • Impedance: 10 kΩS
    • Sync Sensor
    • Connector: BNC (1)
    • Impedance: > 10 kΩ
    • Range: 1- 24 V peak
    • Combination probe (see Flux inputs)
    • External ac sync
    • Connectors: banana jack (2)
    • Range: 50 Vac to 237 Vac

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.