EMFCALC is a program written and provided by Ed Maxey.
The program could prove very helpful to any who face the prospect of a new power line being placed in their neighborhood. It permits rapid calculation of the EMF exposure which the power line specifications will create along the line corridor. It also permits prospective buyers to calculate the EMF before purchasing a home near a power line.
EMFCALC is about 50k and may be run from DOS or from the RUN command in Windows3x, 95 or 98. There is no provision for a hard copy print out, but this can be had via the MARK and COPY function if one is using Windows95 or Windows 98.
The program allows one to set current values and spatial parameters for a transmission line or a transmission line/distribution line combination. One may then select any distance from centerpole and any distance above (or below for that matter) ground level.
The emf for the selected spot then instantly appears in both milligauss and microtesla. Spatial values may be entered in either feet or meters.
EMFCALC is somewhat technical. It allows users to work in either feet or meters with regard to any distance measurement. Assignments of phase, amperage, and spatial arrangement of up to eleven conductors are accommodated.
RMS logic is accurately computed. This is rather interesting as most users are unaware that a 120 volt household device actually is powered at some 340 volts peak to peak.
Net current on the distribution side is automatically determined as well as the current's phase and amplitude. The neutral phase and current are not inserted manually but are dynamically calculated by the program.
One thing is easily demonstrated. If one sets the neutral arm to -90 and then also set the input to the problem at 90, with an unbalanced distribution assignment, half of the net current will be under the input position and there will be a high EMF at that point. This calculation will often be high, demonstrating how stray currents behave.
Pressing the enter key does not change any assigned value. New values must be entered from the keyboard to do that. The exception is that you must type in the entries for X and Y inputs. Also, the underground neutral is turned off whenever the underground ARM setting is 0 (zero). This permits one to observe the benefits of having all return current on the power line as opposed having it run wildly on anything metal in the ground.
Typing either an "f" or "F" (no quotes) after a numerical entry causes the input and output to be in feet. Typing an "m" or "M" after as a suffix to an entry causes input and output to be in meters.
Setting the underground arm to anything other than zero causes the neutral current to be split between the pole neutral and the underground neutral. Dramatic changes in the emf if one positions the underground neutral to a spot near the X position being evaluated. This, of course, will only appear with unequal amperages on the three distribution lines.
One may check the accuracy of the program by placing a very large value for the arm of the neutral while assigning a moderate value to a single distribution line. Then the mathematics for the resulting magnetic field become those of a single current carrier.
The Phase is not given for the neutrals. Rather, the peak amperage value which the computer finds as each degree of the 360░ cycle is processed is stored and displayed. If one assigns 50 amps to the left transmission line and 0░ for the Phase of this line the solution shows the Peak at 90░. If one then change the Phase to 90░ the solution will show the Peak at 0░. Thus, Phase and Peak values progress in opposite directions.
|Upper left Phase 120░___Amps 130.00__Arm -8.00__Height 70.00|
|Lower left Phase 240░___Amps 130.00__Arm -8.00__Height 45.00|
|Middle left Phase 0░____Amps 130.00__Arm -8.00__Height 57.50|
|Upper right Phase 240░__Amps 150.00__Arm 8.00__Height 70.00|
|Middle right Phase 0░___Amps 150.00__ Arm 8.00__Height 57.50|
|Lower right Phase 120░__Amps 150.00__Arm 8.00__Height 45.00|
|Left Phase 120░_______Amps 35.00___Arm -3.50__Height 30.00|
|Middle Phase 0░_______Amps 20.00___Arm 3.50__Height 30.00|
|Right Phase 240░______Amps 15.00 ___Arm 3.50__Height 25.50|
|Neutral Phase 108░_____Amps -19.75__Arm 2.00__Height 20.00|
|Underground Phase 0░__Amps 0.00____Arm 0.00__Height -2.00|
Measurements are in feet.
Press A to adjust factors, H for help, Q to quit, other keys continue:
Distance to centerpole; X Coordinate :? 90
Distance above ground; Y Coordinate :? 5.5
|THETA__X VECTOR__Y VECTOR__ EMF___DIPOLE ANGLE|
The mean EMF at 90 feet from centerpole and 5.5 feet above ground level is 0.45 mG or 0.045 ÁT.
Any key continues
Hopefully this program will prove to be of some value. Please do consider this as a BETA version and kindly let us and Ed Maxey know if you encounter problems.
This program estimates EMF levels. Real life factors such as geography and changes in current loads may lead to different real life levels than those predicted.
The Bridlewood Electromagnetic Fields (EMFs) Information Service and Ed Maxey make this program available as a public service. We do not guarantee its accuracy nor take any responsibility for decisions taken as a result of people using it.
For further technical information please contact Ed Maxey.