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Related Products: |
EMMK-101, EMMK-102, EMMK-103, EMMC-104, EMMC-105, EMMC-106 |
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Related Documents: |
EZDP-2060 |
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Type: |
Troubleshooting |
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Keywords/Labels: |
InsightCM, power values spectrum |
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Summary: |
Describes trends for the Power Spectrum values of the overall scan and four sub-bands. |
InsightCM has the capability of trending features extracted from the EMI overall scan.
For Generators, the trends for the Power Spectrum values of the overall scan and four sub-bands are used.
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Total power (30 kHz – 100 MHz): Overall power of the total spectrum, the band that the levels of concern usually bounce against.
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Low-frequency (30 kHz – 500 kHz): Anomalies are usually found in the generator's exciter area, such as voltage regulator diodes, static exciter, brushless exciter, power rectifiers, etc.
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Low mid-frequency (500 kHz – 5 MHz): Anomalies are usually found in the generator's core/slot area, although sometimes the upper frequency bands can also be affected by internal generator defects.
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Upper mid- frequency (5 MHz – 30 MHz): Anomalies are usually found in the generator's end winding area, although it is sometimes difficult to distinguish issues between the two mid-frequency band areas.
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Upper frequency (30 MHz – 100 MHz): Anomalies are usually found in the Isolated Phase bus (Generator Output bus) area. There are many case studies to support this conclusion.
The sub-bands are compared to the total power band to help validate the defect regions of interest. In the snapshot below, the upper frequency band contributed the most to the total power in band values and the defects were found in the Isolated Phase Bus area.
For Transformers, only the Power Spectrum for the total power in band (full scan) is used. There is not data or case studies to make any conclusions about defect location based upon frequency range yet. However, research is currently being performed to try developing a similar categorization as the generator area.
For Motors, only scans from 30 kHz to 30 MHz (sometimes only 10 MHz) are used. The upper frequencies have never detected any motor issues, which makes sense because motors do not have an Isolated Phase bus structure. For induction motors, the lower frequency band does not have much relevance either because they do not have an excitation system. The scans may be appropriate for Synchronous motors. Although there is not much data associated with synchronous motors, they are similar to generators, so those areas are still monitored. The scan below shows an induction motor with severely contaminated motor windings.
