Utilities Transformer Ground Connection

[mivey]

:slaphead:

It was a joke. :roll:

But true anyway. Probably more than half except near ends.

 

[mbrooke]

The Earth may normally carry more than half the single-phase load so for single-phase circuits you could use 1/2 the conductivity of the phase conductor with some caveats. Caution must be used on heavily loaded taps since the division is not immediate and the neutral at the end carries most of the current and very little is in the Earth.

For two-phase circuits, you need at least 70% conductivity.

For balanced three-phase circuits you could use 20% conductivity but single-phasing conditions dictate using at least 50% conductivity.

20% in any case is considered the minimum.

Other factors:

Future phase conductor upgrades may need a bigger neutral. Sag characteristics (unequal sag/creep, conductor and ground clearance, long spans might need taller poles, etc.) and spacing. Minimum conductor strength for loading and reliability. Use of primary neutral for secondary currents. Fault clearing times are longer with smaller neutrals. Harmonic loading. Minimum sizing for fault withstand.

These percentages based on the NESC? Just wondering.

 

[mivey]

That is true, it makes it work sadly

A matter of perspective. Pros & cons to everything.

 

[mbrooke]

A matter of perspective. Pros & cons to everything.

I agree $$$$ wise there are pros. But for all else, lets agree to disagree

 

[mivey]

These percentages based on the NESC? Just wondering.

20% is NESC IIRC. Common practice for the others.

 

[mivey]

I agree $$$$ wise there are pros. But for all else, lets agree to disagree

Not a matter of agreeing or disagreeing.Fact is there are different perspectives with their associated pros and cons. It doesn't matter to me which perspective you choose.

These are debated, illustrated, discussed in both technical and non-technical works in more detail and volume than I care about.

 

[mbrooke]

Not a matter of agreeing or disagreeing.Fact is there are different perspectives with their associated pros and cons. It doesn't matter to me which perspective you choose.

These are debated, illustrated, discussed in both technical and non-technical works in more detail and volume than I care about.

Not disagreeing, but just adding Mike Holt has covered this extensively. I think he has done some of the best work on the stray voltage/neutral to earth voltage aspect on it.

 

[mivey]

Not disagreeing, but just adding Mike Holt has covered this extensively. I think he has done some of the best work on the stray voltage/neutral to earth voltage aspect on it.

Sakis Meliopoulos is a better expert. He is not too much for layman's lingo though. Super nice guy and about as expert as they come.

 

[mbrooke]

Sakis Meliopoulos is a better expert. He is not too much for layman's lingo though. Super nice guy and about as expert as they come.

Any links? I don't know much about him.

 

[mivey]

Any links? I don't know much about him.

https://www.ece.gatech.edu/faculty-staff-directory/p-meliopoulos



C.W. Brice, G.J. Cokkinides, R.A. Dougal, A.P. Sakis Meliopoulos, R.O. Pettus: "The Virtual Test Bed," Proceedings of the Second Modeling, Simulation, and Virtual Prototyping

A. P. Sakis Meliopoulos, Chapter 27, Lightning and Overvoltage Protection, Standard Handbook for Electrical Engineers, McGraw Hill, 1993, 1999

G.J. Cokkinides, A.P. Sakis Meliopoulos, E.V. Solodovnik: "Stability of Implicit Numerical Methods in Nonlinear Dynamical Systems Simulation," Proceedings of the 30th Southeastern Symposium on System Theory, pp. 27-31, 1998.

T. Chen, A.P. Sakis Meliopoulos, R. Rao: "Audio-to-visual Conversion for Multimedia Communication," IEEE Transactions on Industrial Electronics, 45, pp. 15-22.

A.G. Bakirtzis, G.J. Cokkinides, A.P. Sakis Meliopoulos: "Load-frequency Control Service in a Deregulated Environment," Proceedings of the 31st Annual Hawaii International Confernece on System Sciences, pp. 24-31, 1998.

G. Cokkinides, B. Fardanesh, J. Ingleson, A.P. Sakis Meliopoulos, S. Zelingher: "Multifuncational Synchronized Measurement Network," IEEE Computer Applications in Power, vol. 11, no. 1, pp. 26-30, 1998.

A.P. Sakis Meliopoulos: "Transformer Diagnostics and Power Quality Monitoring," IEEE/PES Winter Meeting, Tampa, FL, 1998.

T.M. Brosnan, A.P. Sakis Meliopoulos, Q.H. Pham, M.J.T. Smith: "SAR ATR with Radon Transform Classifiers," Proceedings on the Federated Laboratory Second Annual Symposium, pp. 215-219, 1998.

G.J. Cokkinides, A.P. Sakis Meliopoulos, E.V. Solodovnik: "Comparison of Implicit and Explicit Integration Techniques on the Non-ideal Transformer Example," Proceedings of the 30th Southeastern Symposium on System Theory, pp. 32-37, 1998.

A.P. Sakis Meliopoulos: "Lightning Safety and Protection," IEE Colloquium on Lightning Protection of Wind Turbines, London, UK, November/December 1997, 1997.

A.P. Sakis Meliopoulos, J.K. Su: "Motion-compensated Interpolation of Untransmitted Frames in Compressed Video," Conference Record of the 1997 Asilomar Conference on Signals, Systems, and Computers, pp. 100-104, 1997.

A. P. Sakis Meliopoulos, W. Adams and R. Casey, "An Integrated Backflashover Model for Insulation Coordination of Overhead Transmission Lines", Electrical Power & Energy Systems, Vol. 19, No. 4, pp. 229-234, May 1997.

A.P. Sakis Meliopoulos: Keynote address: IEE Colloquium on Lightning Protection of Wind Turbines, London, UK, November/December 1997, 1997.

S. Bayrakeri, A.P. Sakis Meliopoulos: "Temporally Scalable Video Coding Using Nonlinear Deinterlacing," Proceedings of the 1997 IEEE Data Compression Conference, p. 423, when?, p. 423, 1997.

Y. Tang and A. P. Sakis Meliopoulos, 'Power System Small Signal Stability Analysis with FACTS Elements', IEEE Transactions on Power Delivery, Vol. 12, No. 3, pp. 1352-1361, July 1997.

A.P. Sakis Meliopoulos, Y. Tang: "Power System Small Signal Stability Analysis with FACTS Elements," IEEE Transactions on Power Delivery, vol. 12, no. 3, pp. 1352-1361, 1997.

S. Bayrakeri, A.P. Sakis Meliopoulos: "MPEG-2 Nonlinear Temporally Scalable Coding and Hybrid Quantization," Proceedings of the 1997 IEEE International Conference on Acoustics, Speech, and Signal Processing, pp. 2629-2632, 1997.

M.Z. Coban, A.P. Sakis Meliopoulos: "Computationally Efficient Exhaustive Search Algorithm for Rate-constrained Motion Estimation," Proceedings of the 1997 IEEE International Conference on Image Processing, vol. 1, pp. 101-105, 1997.

C.H. Lee, A.P. Sakis Meliopoulos: "Wavelet Baed Transient Analysis," Proceedings of the 1997 North American Power Symposium, pp. 339-346, 1997.

W. Gass, F.H. Lin, A.P. Sakis Meliopoulos: "Vision Model Based Video Perceptual Distortion Measure for Video Processing and Applications," Proceedings of the 1997 IEEE International Conference on Acoustics, Speech, and Signal Processing, pp. 3133-3138, 1997.

A.P. Sakis Meliopoulos, J.K. Su: "Non-iterative Rate-constrained Motion Estimation for Overlapped Block Motion Compensation," Proceedings of the 1997 IEEE International Conference on Image Processing, vol. 2, pp. 33-37, 1997.

W. Gass, F.H. Lin, A.P. Sakis Meliopoulos: "Video Perceptual Distortion Measure: Two-dimensional Versus Three-dimensional Approaches," Proceedings of the 1997 IEEE International Conference on Image Processing, vol. 3, pp. 460-462, 1997.

G.J. Breaux, P.J. Chamoun, J.A. Gavin, R.I. James, A.P. Sakis Meliopoulos: "Ground Fault Protection of Impedance Grounded Systems: A Case Study," Proceedings of the Georgia Tech Protective Relaying Conference, Atlanta, GA, 1996.

D.L. Garrett, A.P. Meliopoulos, Shashi G. Patel: "Distribution Grounding Handbook," EPRI TR-106661-V1, 3066-01, Final Report, August, 1996.

A.P. Sakis Meliopoulos, F. Zhang: "Multiphase Power Flow and State Estimation for Power Distribution Systems," IEEE Transactions on Power Systems, vol. 11, no. 2, pp. 939-946, 1996.

R.I. James, A.P. Sakis Meliopoulos: "Grounding System Testing with EPRI's Smart Ground Multimeter," Substation Equipment Diagnostic Conference, New Orleans, LA, 1996.

Feng Xia and A. P. Sakis Meliopoulos, 'A Methodology for Probabilistic Simultaneous Transfer Capability Analysis,' IEEE Transactions on Power Systems, Vol. 11, No. 3, pp. 1269-1278, August 1996.

W. Adams, R. Casey, A.P. Sakis Meliopoulos: "Effects of Tower Grounding System Models on Insulation Coordination of Overhead Transmission Lines," Proceedings of the International Conference on Power Systems Transients, pp. 469-474, 1995.

B. Fardanesh, A.P. Sakis Meliopoulos: "Phasor Measurement Applications-Transmission Line Loss Measurement and Parameter Identification: Monitoring for Transformer Unbalanced Operation," Fault and Disturbance Analysis and Precise Measurements in Power Systems Conference, Arlington, VA, 1995.

A.P. Sakis Meliopoulos: "Embedded System Applications to Power Systems," presented at the New Orleans IEEE Section Meeting, New Orleans, LA, 1995.

A.P. Sakis Meliopoulos: "Optimization of Tower Ground Resistance," presented at the EPRI Workshop on Transmission Grounding and Lightning Performance Improvement, Nashville, TN, January, 1995.

A. P. Sakis Meliopoulos, F. Zhang, and S. Zelingher, 'Power System Harmonic State Estimation,' IEEE Transactions on Power Systems, Vol 9, No. 3, pp 1701-1709, July 1994.

H. Abdallah, G. Cokkinides, S. Duong, A.P. Meliopoulos, S.G. Patel: "A PC Based Ground Impedance Measurement Instrument," IEEE Transactions on Power Delivery, vol. 8, no. 3, July, 1993.

A. P. Meliopoulos, G. J. Cokkinides, and Xing Yong Chao, "A New Probabilistic Power Flow Analysis Method," IEEE Transactions on Power Systems, vol. 5, no. 1, pp. 182-190, February 1990.

 

[mivey]

and Sakis helped Mike Holt with his analysis.

 

[Joseph P.]

How did you make all of the ground resistance measurements?

AEMC 6416 Clamp-on Ground Resistance Meter

 

[mbrooke]

https://www.ece.gatech.edu/faculty-staff-directory/p-meliopoulos



C.W. Brice, G.J. Cokkinides, R.A. Dougal, A.P. Sakis Meliopoulos, R.O. Pettus: "The Virtual Test Bed," Proceedings of the Second Modeling, Simulation, and Virtual Prototyping

A. P. Sakis Meliopoulos, Chapter 27, Lightning and Overvoltage Protection, Standard Handbook for Electrical Engineers, McGraw Hill, 1993, 1999

G.J. Cokkinides, A.P. Sakis Meliopoulos, E.V. Solodovnik: "Stability of Implicit Numerical Methods in Nonlinear Dynamical Systems Simulation," Proceedings of the 30th Southeastern Symposium on System Theory, pp. 27-31, 1998.

T. Chen, A.P. Sakis Meliopoulos, R. Rao: "Audio-to-visual Conversion for Multimedia Communication," IEEE Transactions on Industrial Electronics, 45, pp. 15-22.

A.G. Bakirtzis, G.J. Cokkinides, A.P. Sakis Meliopoulos: "Load-frequency Control Service in a Deregulated Environment," Proceedings of the 31st Annual Hawaii International Confernece on System Sciences, pp. 24-31, 1998.

G. Cokkinides, B. Fardanesh, J. Ingleson, A.P. Sakis Meliopoulos, S. Zelingher: "Multifuncational Synchronized Measurement Network," IEEE Computer Applications in Power, vol. 11, no. 1, pp. 26-30, 1998.

A.P. Sakis Meliopoulos: "Transformer Diagnostics and Power Quality Monitoring," IEEE/PES Winter Meeting, Tampa, FL, 1998.

T.M. Brosnan, A.P. Sakis Meliopoulos, Q.H. Pham, M.J.T. Smith: "SAR ATR with Radon Transform Classifiers," Proceedings on the Federated Laboratory Second Annual Symposium, pp. 215-219, 1998.

G.J. Cokkinides, A.P. Sakis Meliopoulos, E.V. Solodovnik: "Comparison of Implicit and Explicit Integration Techniques on the Non-ideal Transformer Example," Proceedings of the 30th Southeastern Symposium on System Theory, pp. 32-37, 1998.

A.P. Sakis Meliopoulos: "Lightning Safety and Protection," IEE Colloquium on Lightning Protection of Wind Turbines, London, UK, November/December 1997, 1997.

A.P. Sakis Meliopoulos, J.K. Su: "Motion-compensated Interpolation of Untransmitted Frames in Compressed Video," Conference Record of the 1997 Asilomar Conference on Signals, Systems, and Computers, pp. 100-104, 1997.

A. P. Sakis Meliopoulos, W. Adams and R. Casey, "An Integrated Backflashover Model for Insulation Coordination of Overhead Transmission Lines", Electrical Power & Energy Systems, Vol. 19, No. 4, pp. 229-234, May 1997.

A.P. Sakis Meliopoulos: Keynote address: IEE Colloquium on Lightning Protection of Wind Turbines, London, UK, November/December 1997, 1997.

S. Bayrakeri, A.P. Sakis Meliopoulos: "Temporally Scalable Video Coding Using Nonlinear Deinterlacing," Proceedings of the 1997 IEEE Data Compression Conference, p. 423, when?, p. 423, 1997.

Y. Tang and A. P. Sakis Meliopoulos, 'Power System Small Signal Stability Analysis with FACTS Elements', IEEE Transactions on Power Delivery, Vol. 12, No. 3, pp. 1352-1361, July 1997.

A.P. Sakis Meliopoulos, Y. Tang: "Power System Small Signal Stability Analysis with FACTS Elements," IEEE Transactions on Power Delivery, vol. 12, no. 3, pp. 1352-1361, 1997.

S. Bayrakeri, A.P. Sakis Meliopoulos: "MPEG-2 Nonlinear Temporally Scalable Coding and Hybrid Quantization," Proceedings of the 1997 IEEE International Conference on Acoustics, Speech, and Signal Processing, pp. 2629-2632, 1997.

M.Z. Coban, A.P. Sakis Meliopoulos: "Computationally Efficient Exhaustive Search Algorithm for Rate-constrained Motion Estimation," Proceedings of the 1997 IEEE International Conference on Image Processing, vol. 1, pp. 101-105, 1997.

C.H. Lee, A.P. Sakis Meliopoulos: "Wavelet Baed Transient Analysis," Proceedings of the 1997 North American Power Symposium, pp. 339-346, 1997.

W. Gass, F.H. Lin, A.P. Sakis Meliopoulos: "Vision Model Based Video Perceptual Distortion Measure for Video Processing and Applications," Proceedings of the 1997 IEEE International Conference on Acoustics, Speech, and Signal Processing, pp. 3133-3138, 1997.

A.P. Sakis Meliopoulos, J.K. Su: "Non-iterative Rate-constrained Motion Estimation for Overlapped Block Motion Compensation," Proceedings of the 1997 IEEE International Conference on Image Processing, vol. 2, pp. 33-37, 1997.

W. Gass, F.H. Lin, A.P. Sakis Meliopoulos: "Video Perceptual Distortion Measure: Two-dimensional Versus Three-dimensional Approaches," Proceedings of the 1997 IEEE International Conference on Image Processing, vol. 3, pp. 460-462, 1997.

G.J. Breaux, P.J. Chamoun, J.A. Gavin, R.I. James, A.P. Sakis Meliopoulos: "Ground Fault Protection of Impedance Grounded Systems: A Case Study," Proceedings of the Georgia Tech Protective Relaying Conference, Atlanta, GA, 1996.

D.L. Garrett, A.P. Meliopoulos, Shashi G. Patel: "Distribution Grounding Handbook," EPRI TR-106661-V1, 3066-01, Final Report, August, 1996.

A.P. Sakis Meliopoulos, F. Zhang: "Multiphase Power Flow and State Estimation for Power Distribution Systems," IEEE Transactions on Power Systems, vol. 11, no. 2, pp. 939-946, 1996.

R.I. James, A.P. Sakis Meliopoulos: "Grounding System Testing with EPRI's Smart Ground Multimeter," Substation Equipment Diagnostic Conference, New Orleans, LA, 1996.

Feng Xia and A. P. Sakis Meliopoulos, 'A Methodology for Probabilistic Simultaneous Transfer Capability Analysis,' IEEE Transactions on Power Systems, Vol. 11, No. 3, pp. 1269-1278, August 1996.

W. Adams, R. Casey, A.P. Sakis Meliopoulos: "Effects of Tower Grounding System Models on Insulation Coordination of Overhead Transmission Lines," Proceedings of the International Conference on Power Systems Transients, pp. 469-474, 1995.

B. Fardanesh, A.P. Sakis Meliopoulos: "Phasor Measurement Applications-Transmission Line Loss Measurement and Parameter Identification: Monitoring for Transformer Unbalanced Operation," Fault and Disturbance Analysis and Precise Measurements in Power Systems Conference, Arlington, VA, 1995.

A.P. Sakis Meliopoulos: "Embedded System Applications to Power Systems," presented at the New Orleans IEEE Section Meeting, New Orleans, LA, 1995.

A.P. Sakis Meliopoulos: "Optimization of Tower Ground Resistance," presented at the EPRI Workshop on Transmission Grounding and Lightning Performance Improvement, Nashville, TN, January, 1995.

A. P. Sakis Meliopoulos, F. Zhang, and S. Zelingher, 'Power System Harmonic State Estimation,' IEEE Transactions on Power Systems, Vol 9, No. 3, pp 1701-1709, July 1994.

H. Abdallah, G. Cokkinides, S. Duong, A.P. Meliopoulos, S.G. Patel: "A PC Based Ground Impedance Measurement Instrument," IEEE Transactions on Power Delivery, vol. 8, no. 3, July, 1993.

A. P. Meliopoulos, G. J. Cokkinides, and Xing Yong Chao, "A New Probabilistic Power Flow Analysis Method," IEEE Transactions on Power Systems, vol. 5, no. 1, pp. 182-190, February 1990.

Thank you! I now have some reading to do

 

[Joseph P.]

While not a good measure, I hope it was clamp-on. Lifting a POCO ground can be dangerous if there is a problem.

AEMC 6416 Clamp-on Ground Resistance Meter.

 

[ATSman]

The engineering manager for one of the larger utilities in our rural area had just finished a very thorough neutral /stray ground current investigation on their electrical distribution system.They concluded only 40 % of their neutral current was returning back to their substation on their overhead neutral wires--the rest of this neutral current was flowing back through their customer's grounding systems to the substation transformer.

Do you have a link to this study/ report?

 

[ghostbuster]

Do you have a link to this study/ report?

Sorry,all the study detailed results are the property of this utility .

 

[mivey]

AEMC 6416 Clamp-on Ground Resistance Meter.

Just be aware that is not a reliable method to measure ground rod resistance.

 

[Joseph P.]

Just be aware that is not a reliable method to measure ground rod resistance.

On the Mike Holt video where he was driving ground rods at his office, that was the meter he used and when comparing to the three point method which they also used, the results were close. What style of measurement is accurate in your opinion?

 

[mbrooke]

On the Mike Holt video where he was driving ground rods at his office, that was the meter he used and when comparing to the three point method which they also used, the results were close. What style of measurement is accurate in your opinion?

Question. Why did you feel the need / think it was necessary to lower your grounding electrode resistance? I do not mean to come across as critical, just wondering.

 

[peter d]

I live in Long Island NY where the earth material is sand. My ground system with an was 215 ohms. I reduced it to 5.3 ohms by driving 70' of sectional ground rod. When I checked the utilities ground connection at the pole coming off of the transformer, it was 465 ohms. Does the utility have to follow the NEC code where you need under 25 ohms on the ground? I am having a stray voltage situation on the property near the pole and feel it is from their bad ground connection.

Pfft, lame. I drove a 15,000 foot rod and was able to get 0.000001 ohms.