Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC...
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Transcript of Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC...
![Page 1: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/1.jpg)
Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics
in Oil Impregnated PILC Cables
Zachary M. ThomasWolf, Greenfield & Sacks P.C.
Markus ZahnMassachusetts Institute of Technology
![Page 2: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/2.jpg)
Presentation Outline
• Motivation
• Dielectrometry Sensors
• Sample Materials and Setup
• Constant Temperature Measurements
• Transient Measurements
• Summary
![Page 3: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/3.jpg)
Motivation• Develop technology for cable health monitoring.• What can dielectrometry sensors tell us about the electrical
properties of PILC insulation?
Cable Aging Mechanisms• Temperature Fluctuations
– Temperature varies with loading conditions.• Moisture Ingress
– Cracks and corrosion provide sights.– Aging of cellulose releases water.
• Partial Discharge (PD)– Formed in gaps and voids formed during temperature cycling in the
cable insulation.– Regions of low oil content.
![Page 4: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/4.jpg)
Dielectrometry Sensors
• Capacitive sensing technique.• Requires access to one
surface of MUT (material under test).
• Sensor response determined by MUT “effective permittivity”
• Periodicity i.e. wavelength determines sensor’s “depth perception.”
• Frequency domain measurements taken from mHz to kHz.
3 λ Sensor
![Page 5: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/5.jpg)
Sensor Excitation
![Page 6: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/6.jpg)
Sensor Theory
![Page 7: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/7.jpg)
Field Line Results
![Page 8: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/8.jpg)
Sample Materials and Setup
• Sample Materials– PILC – Paper insulated
lead covered cables– Teflon– Wood (Birch & Oak)– Polycarbonate– Polyethylene– Acrylic
• Experiments conducted in a vacuum chamber.
![Page 9: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/9.jpg)
Single Conductor Cable Constant Temp. Measurements
![Page 10: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/10.jpg)
Arrhenius Temperature Dependence
Observe:Changes in temperature cause
a frequency shift of the permittivity.
• Dependence described by activation energy.
![Page 11: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/11.jpg)
Transient Measurements
• We wish to observe moisture moving through test materials.
• Transient measurements are taken at a single temperature.
• Before time zero chamber is typically dried.
• At time zero moisture admitted into the chamber.
• Sensor is monitored at several frequencies during the diffusion process.
![Page 12: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/12.jpg)
Maple Rod Measurements (130 F, 30% RH)
Tim
e, d
ays
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Maple Rod Mapping at 1 Hz
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Maple Rod Moisture Profiles at 1 Hz
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Single Conductor Cable Measurement
Tim
e, d
ays
![Page 16: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/16.jpg)
Single Conductor Cable Mapping at 1 Hz
![Page 17: Dielectrometry Measurements of Moisture Diffusion and Temperature Dynamics in Oil Impregnated PILC Cables Zachary M. Thomas Wolf, Greenfield & Sacks P.C.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f335503460f94c4f532/html5/thumbnails/17.jpg)
Summary
• Theoretical solutions have been derived and tested for new geometries.
• Steady state measurements detail the permittivity’s dependence on temperature. Arrhenius temperature dependence is characterized.
• Transient moisture measurements provide insight into moisture dynamics in woods and cables.
• With the lead sheath in place, dielectrometry is not practical for manhole measurements.
• Dielectrometry sensors could be used as an inexpensive method for utilities to assess cable health.
• Future measurements should focus on comparing dielectric properties of failed and failing cables to healthy cables.