Potential contour survey in vicinity of a substation.

[EPItestman]

I am looking for recomendations in test equipment and methods to make physical voltage measurement in a park next to a substation. The spec. references IEEE 81P. A potential contour map is to be generated to determine hazardous voltage gradients.

 

[cuky2000]

1- I am presuming that there is an existing substation and the initial scope of work is to measure the step and touch potential in the park in accordance with the IEEE Standard # 81, “Guide for Measuring Ground Resistance and Potential Gradients in the Earth”. Sample of commercial tester are as follow:

http://specs.repaircalibration.com/2114.95.pdf

http://iss

http://www.co.uk/pdf/chauvin/terca2.pdf

http://www.lightningeliminators.com/Grounding/SGT Q&A-Rev C-101904.pdf

2- The second task, is to map the measured field data in a scale drawing

3- This task probable will evaluate the field data again the allowable step and touch potentials plotted on the drawing.
_{[blue]Please notice that the allowable step and touch potential need to be calculated and varies for different surfacing materials. For instance, gravel, concrete, asphalt and native soil may produce different allowable values.[/blue]}

 

[jghrist]

The difficulty that I see in measuring step- and touch-potentials in a park adjacent to a new substation is that the potentials after energizing the station may be greatly influenced by distribution system neutral connections that do not exist before energizing the station.

In particular, I'm thinking of park equipment that is grounded to services that are connected at distribution transformers to the distribution system neutral. If the distribution feeder is fed from the new substation, the neutral will be bonded to the ground grid.

During a fault, the park equipment may have significant transferred potential and a large touch-potential. Measurements before the distribution feeder neutral is connected to the substation ground grid may not show this touch-potential.