Advantages of the Smart Ground System

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2100-A Palmetto St., Clearwater, FL 33765800-749-6800

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Per IEEE Std. 81, IEEE Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Grounding System there are a number of problems, with the standard test meter and methodology, which must be considered and mitigated.

Complexities:

The measurements of soil resistivity, ground impedance, and potential gradients of the earth introduce a number of complexities not encountered in other resistance, impedance, and potential measurements. In some situations, it might be necessary to perform several measurements to plot trends and analyze the situation. Stray currents and other factors can interfere with the measurements.

With development and industrial growth adjacent to power substations, choosing a suitable pattern or location for test probes to make a resistance test is becoming increasingly difficult. The connection of overhead ground wires, buried water pipes, cable sheaths, adjacent railroad tracks, conveyor systems, and so on, can all have an effect on the electrical circuit being tested and can introduce significant errors. It should also be noted that overhead ground wires might be insulated either deliberately or by poor connections, and therefore, low-voltage tests might give answers different from actual fault tests.To improve the accuracy of the measurement for comparison with calculated values, ground impedance measurements can be performed prior to interconnection of external shield wires, metallic pipes, and other external interferences. *- IEEE Std. 81

*Before StartupNoted Considerations: Test electrodes: Electrode/Probe resistance may be too high. Power limitations of the

meter may not provide enough circulating current. Typical meters are capable of up to250mA at 50V

Stray DC & AC currents: Stray currents can seriously interfere withmeasurements. In either case it is best to have a measuring device capable ofgenerating test signals that are pulsed/alternating and are different in frequencythat that of stray currents.

The Smart Ground meter is capable of 500V, 15 Amperes A probe performance report allows the user to determine if the resistance of

the probes are too high and take corrective action, if needed.

Smart Ground utilizes a random pulsed signal from 0-200Hz

2100-A Palmetto St., Clearwater, FL 33765800-749-6800

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Reactive component of impedance of large grounding system: grids at power frequency

Smart Ground employs a spread spectrum signal up to 2kHz, removespower frequency noise and eliminates error.

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Buried metallic objects, e.g. fences, rails & pipelines

Other Considerations:

The standard meter and methodology is not practical, nor advisable, in this day and age due to compounding errors and unknowns.

Coupling between test leads. Any voltage produced in the potential lead due toinductive coupling from current flowing in the current lead is directly added to the truevoltage and produces a measurement error.

Smart Ground test cables are shielded to mitigate coupling. Test personnel are trained to properly route cables to avoid possible scenarios

The ground system editor allows for the modeling of such objects so theireffect can be quantified.

system to be tested must be de-energized and isolated: Not practical and The grounding too costly Smart Ground can test on energized and connected systems. In fact, the

electro-geometric model will include the connected network. Excessive lead lengths required to measure large grids. Small grids require 5x the diagonal

distance of the grid. Larger grids require more lead length - nonlinear. Very difficult, even in rural areas, e.g. private property, rivers, fences, power lines Smart Ground only requires 2x. Much more capable in congested

industrial locations. Wire leads to probes can be adversely affected by electrical noise (EMI, RFI). The leads

act as antennas. The longer the lead, the greater the effect.

Smart Ground leads are shorter than the typical system and are shielded.Hardware filters and algorithms withtin the software identify and remove noise.

Low signal to noise ratio may result in errors: Large grids result in low resistance and low test signals - S/N ratio errors The Smart Ground system utilizes a high power signal and filtering to minimize S/N ratio

errors. The test results have unknown confidence factors - accuracy of testing are not provided. Minimal-to-no self-diagnostics of the test equipment. With the standard test meter and methodology, all you get is a number...

Smart Ground Mitigates all problems/issues and identified in IEEE Std.81 Smart Ground is a recognized methodology in IEEE Std. 81 and is EPRI

approved All audits are reviewed by Dr. Sake Meliopoulos