This photo shows the overall lab and electrolytic tank'

1

• This photo shows the overall lab and electrolytic
  tank.

2

• The layout of the model test probes is shown in
  this photo. The white probes are spaced 6 inches
  apart and were used to measure the tank water
  resistivity at a depth of 6 inches. The black
  probe offset from the others is the temporary
  ground rod (TGR) probe and the other three probes
  (spaced 0.0413 m from the TGR) are the probes
  used to measure touch, step, and transfer touch
  potential.

3

• This photo shows the underside of the model.
  The model substrate is Styrofoam which was used
  because of it is an insulator at the voltages
  being used, it floats and provides a
  self-leveling substrate for the probes and
  ensures consistent contact with water surface,
  and it is easy to work with.

4
Slide 3 Continued

• The model scale is 0.5-inch 1 foot. This scale
  was chosen based on tank dimensions and the need
  to simulate remote ground, the types and sizes of
  grounding electrodes to be modeled, and the rim
  size of a 22 caliber casing which is
  approximately 0.25 inches. In Phase I it was
  determined to use a circular metallic plate with
  a radius of 8 cm for the human foot per previous
  research performed and IEEE standards. This was
  the dimension used for the base of the test legs
  that were fabricated earlier this year for field
  testing. The diameter of the circular metallic
  plate is 0.52 foot which is very close at the
  0.5-inch scale to the rim diameter of a 22
  caliber casing.
• The TGR probe is 2.5 inches which equates to 5
  feet which is the maximum depth that a TGR is
  installed at the worksite. The diameter of the
  12 solid copper conductor used to model a TGR is
  greater than a TGR is at 0.5 inch scale. However,
  the resistivity of a TGR or probe is not
  sensitive to its diameter and 12 was used for
  its stiffness. In further tests a wire gage that
  better matches the diameter of a TGR in scale
  will be used but it is not expected to impact the
  measurements.
• As noted above, the electrodes used to measure
  touch, step, and transfer step voltage are 22
  caliber casings set flush with the Styrofoam
  substrate to simulate a person standing on grade
  in the vicinity of a TGR. A 12 solid copper
  conductor is soldered to the inside of the casing
  to provide a connection point for measurements.

5

• Shows the underside of the model from a
  different angle. The step voltage probes are
  spaced at a scaled 1 meter from one another per
  IEEE standards for step and touch voltage.

6

• This photo shows one of the four probes used to
  measure water resistivity.
• These probes are 0.25 inches because they need
  to be less than one-twentieth of the distance
  between them for the Wenner 4-point test method.
  An AEMC Model 4620 was used to measure water
  resistivity which has varied from about 17.0
  ohm-meter to bout 19.6 ohm-meter over the past
  couple of weeks. The resistivity measured by the
  AEMC Model 4620 was checked against measurements
  using a conductivity meter and Humboldt soil
  resistivity box. The AEMC resistivity and
  conductivity meter measurements are close
  indicating that the AEMC meter can be used for
  this purpose. The Humbolt soil box gives a higher
  resistivity measurement (about 20 ohm-meter) but
  I think this is due to the DC power supply that I
  am using which is too small for the purpose. I
  will have a bigger DC power supply later this
  week that should be able to better simulate a
  constant current source and hopefully resistivity
  measurements that are closer to the AEMC tank
  measurements and the conductivity meter
  measurements

7

• Another photo of the tank and model at a
  different angle.

8

• Shows the probe connections and the model in the
  tank.
• These connections will be made using screw
  terminals and 14 stranded CU conductor in
  further model testing. Alligator clip jumpers
  were used for the preliminary tests because they
  make for an easier set up.

9

• Photo of the equipment used to perform
  measurements. Fluke models 179, 335, and 189
  multimeters with AEMC model 4620 in background.

10

• THANKS TO KCPL
• I want to thank Brian Flier at KCPL for
  providing me with transmission line parameters
  last week. They will be very helpful.
• NON-DESTRUCTIVE IN-SERVICE TEMPORARY GROUND
  JUMPER ASSEMBLY TESTING
• Jeff Thomas (KU Jeff - not A. B. Chance Jeff) is
  doing his master's thesis on non-destructive
  in-service temporary ground jumper assembly
  testing. We will be experimenting with methods
  other than resistance to detect connection and
  cable problems. If anyone can lend us some TGJAs
  (good and bad) to experiment with we would
  appreciate it.
• Created by rsolwa on October 19, 2006
• Last updated June 20, 2006