Shaft Ground Monitoring FAQ
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What voltage and current readings should I expect on my generator?
The OEM usually provides nominal voltage and/or current expectations. “Normal” shaft voltage and current levels vary widely from generator to generator, even two of the same make and model. Establishing a baseline is crucial for proper analysis. We recommend running fresh grounding ropes on a clean shaft surface and monitoring your equipment for a month or so to determine the normal shaft voltage and current ranges for each of your units. From there, focus on the trending of those values. A departure from the normal voltage and current ranges you have established can be a strong indicator that maintenance is warranted.
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What should I do if my shaft voltage and/or shaft current exceed my established acceptance criteria?
The leading cause of increases in shaft voltage is a deteriorated shaft-to-rope contact, either by way of contamination or shaft surface deterioration. In cases like this, cleaning the shaft will typically lower the voltages back below the acceptance criteria. If a more aggressive cleaning is required, inquire with Cutsforth™ about a shaft stoning service. If you have any questions or concerns about the shaft voltage or current levels on your system, reach out to Support@Cutsforth.com.
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Do we need the Cutsforth™ Shaft Grounding Assembly to implement Cutsforth™ Shaft Ground Monitoring systems?
Yes, our Shaft Ground Monitoring systems are only compatible with Cutsforth™ grounding assemblies.
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What are the differences among the Cutsforth™ Shaft Ground Monitoring systems?
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Assurance Shaft Ground Monitoring: measures and displays real time voltage, current, and ground rope status. Additionally, the system can pass the real time measurements to a DCS or historian.
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Premium Shaft Ground Monitoring: continuously measures voltage, current, and ground rope status. The system provides multi-level alarming and time domain waveforms for both voltage and current for analysis. Waveform analysis can detect a wide range of defects, including poor shaft conditions to overheating of the stator core.
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