Page 2 - PDTrac Tech Overview
P. 2

ON-LINE MONITORING THE EFFICIENT WAY

          The What?

            The What … Partial Discharge
            … because the PD monitoring system uses VHF and time-of-flight to automatically filter out noise and classify disturbances, then the output of the PDTrac
            monitor is only the PD detected by each sensor.  As such, the DCS can be configured to trend (doubling over a twelve-month interval) and when compared
            to the Iris database issue alerts, warnings, and notifications.  Additionally, the polarity of the PD pulses is tracked individually, so whether the source is
            polarity predominant and/or correlates with load or temperature can be determined.  This makes it possible to determine the problem coils and if the
            problems are likely due to thermal deterioration, coil/bar movement, surface activity or deterioration of the turn insulation.

                                        400
                                           High 217-360mV
                                        350
                                        300
                                       Peak Magnitude (mV)  250                            C1 Qm+
                                        200
                                                                                           C1 Qm-
                                        150
                                                                                           Linear (C1 Qm+)
                                        100
                                           Moderate 62-316mV                               Linear (C1 Qm-)
                                        50
                                           Typical <62mV
                                         0
                                         9/15  10/15  11/15 12/15  1/16  2/16  3/16  4/16  5/16  6/16  7/16  8/16  9/16  10/16
                                                              Month/Year
                                      Iris Power provides a solution that separates electrical noise like partial
                                      discharge and other disturbances in the power system from the asset
                                      partial discharges. In cases where there is 30 m or more of power cable to
                                      the generator, high frequency system noises that resemble machine partial
                                      discharges are attenuated by the power cable.

                                      The remaining low frequency disturbances from the power system
                                      are eliminated using the Iris Power 80 pF capacitive sensors. The
                                      sensors attenuate all low frequency electrical noises below 40MHz
                                      leaving only the machine partial discharges to be analyzed. Pulse
                                      shape is then automatically analyzed to ensure only machine partial
                                      discharges are presented in the data output. Low frequency solutions like
                                      those using 1000 pF couplers do not block these frequency ranges.
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