By Expert Systems Programs and Consulting, Inc.

Expert Systems       9501 Tinker Court Burke , VA 22015

Frequently Asked Questions

Q.  When I enter data into the "Line Fault Current" cell of the "By the Numbers" page, the number I enter is changed to Zero.  When I enter a number into the "Grid Resistance" cell the number I enter is changed to ,,,0,0   What's wrong?

A.  Your standard computer language setting is not set for English (U.S.) and the program is getting the wrong information when you hit the tab or enter key.   You must go the the "Regional Settings" icon under the "Control Panel" icon which is under the "My Computer" icon, and change the language to English (U.S.) and then restart your computer for the change to take effect.  Then the "By the Numbers" computation package should operate properly.  This problem and solution was discovered by our GPR-Expert users in Canada, to whom we will be eternally grateful. 

Q.   My company has a policy that its employees cannot install any computer software on a company-owned computer if the software hasn't been approved for installation by the company. Would using GPR-Expert computer program violate that policy?

A.   No. When you run The GPR-Expert computer program, the program does not install itself onto the hard drive of the computer. No executable or support files are copied onto the computer and the computer program remains totally resident on the CD-ROM disk. The computer program therefore uses no space on the hard drive. Of course, if you copy the files from the CD-ROM disk onto your hard drive you would be violating your company's no-installation policy.  However, there is no reason to copy the contents of the CD-ROM onto your computer because the program will not run from a copy placed on any drive in your computer or on a network server.

If your company performs routine inventories of the computer software installed on its company-owned computers, the GPR-Expert program will never show up in an inventory check because it never becomes resident on any computer, if used as it is licensed to be used.

Q.   If I buy a copy of the GPR-Expert program on CD-ROM can I loan the CD disk to a coworker to use?

A.   Yes. When you purchase the GPR-Expert on CD-ROM you are not purchasing just personal rights to use the program, you are purchasing the CD which can be used on any computer at anytime so long as additional copies are not made or distributed. One office can purchase the disk and keep it in a central location such as a library, and anyone can come and check it out to use at anytime and not violate the licensing agreement---that's the beauty of the packaging of the GPR-Expert program so that it can only be run from the CD-ROM disk directly.

Q.   Can the line fault current in amperes rms, which is the first input value in the GPR-Expert program, represent simultaneous multiple phase faults?

A.   No. The line fault current input value is for a single phase fault to ground only. 

Q.   I want to describe my project with more than just its name. Is that possible?

A.   Yes. The project name fields in the "By The Numbers" and "Induction Calculations" windows of GPR Expert are not just one-line fields. The project name information can include up to 32 Kilobytes of text with an unlimited number of lines of text.  To add text lines to the project name just hold down the control key and depress the Enter key.  This will add a text line in the project field.  You can add as many lines as you need to describe the project or to make notes about the case you are computing.  To move through the text just use the arrow keys.  The only text that can be seen, or that will print when you print the window, is the line of text showing in the one-line display of the Project Name field.

Q.   I don't want to save my project case studies in the C:\GPR directory that the GPR Expert program creates. Can I save my projects elsewhere?

A.   Yes.  You can save your cases anywhere you would like.  Just select the drive letter and subdirectory in the files window that pops up when you select the "SAVE AS" option under the files menu.

Q.   I'm in Europe and want to do all the input in units of meters rather than feet.  Do I have to enter the units in feet and have the program convert the distances to meters?

A.   No. You can enter your distances in the Meters units fields and the program will convert your distances to feet  automatically.  The program was written so that a user can enter the data directly in either feet or meters so long as the user enters the feet in the Feet field and meters in the Meters field.

Q.   Can I use the program to compute the 300-Volt Point for any substation or site regardless of the grid size?

A.   No. The program's computational algorithms were designed based on 300-Volt Point data for grid sizes from 400 square feet (37 square meters) to 935,000 square feet (86,863 square meters).  The program will not allow input of smaller or larger grid sizes, even though it could compute 300-Volt Point values for smaller or larger grids.   We included this limitation because the program isn't calibrated to produce results that would meet our standards outside that grid size range.

Q.   The soil in my part of the country is saturated and has lower resistivity than even the Soil One classification in the program. Is the program computing unreasonably large 300-Volt Point distances for wet, low-resistivity soils?

A.   No, we don't believe so. Soil One, the 100 meter-ohm soil twenty feet deep overlying 20 meter-ohm soil would represent an average dry soil over a lower resistivity or saturated soil.  We believe it would be unreasonable to assume that soils would remain saturated almost to the ground surface for years and years.  Even though a GPR site may be located adjacent to a swampy area that has very low soil resistivity, that condition can change over time.  During a long drought period the water table can drop tens of feet and the soil resistivity can thereby increase dramatically.    Remember that conditions, especially environmental conditions, change over time and equipment designed to last 30 or more years must be designed to operate safely over any conditions that are likely to occur over such an extended time period.

      The increased cost of designing protection with a conservative 300-Volt Point distance is very small compared to the cost of a protection failure caused by designing with too short a 300-Volt Point distance.  If one feels that the program gives an overly conservative 300-Volt Point distance for an area that is characterized by unusually low soil resistivity, then the designer should use a more complex computational program that can accept any input soil resistivity, such as the EPRI Workstation Program.

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