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EPRI Releases EMFW 2.5

By John R. Pappa
Enertech Consultants

The Electric Power Research Institute (EPRI) announces the release of Electric and Magnetic Fields Workstation (EMFW) version 2.5. The EMFW provides a set of tools that allow users to model electric and magnetic fields (EMF) produced by electric power lines and substations. The EMFW consists of several EPRI EMF programs combined into a single package for ease of use. The EMFW runs in the Microsoft® Windows® 3.1, 95 and NT operating systems. The EMFWorkstation was previously called the EMWorkstation.

The EMFW version 2.5 adds one new module and retains five original modules from the previous EMW 2.0. The new module consists of an EMF expert system. Updates to the original modules include RESICALC, SUBCALC, EXPOCALC, ENVIRO, and the Power Line Calculator. The EMFW modules are described in detail below:

EMFX 1.0 - This EMF Expert System contains a great deal of information about many aspects of magnetic fields and management of magnetic fields. It includes tutorials on EMF, transmission line magnetic fields, and distribution line magnetic fields. The tutorials describe topics ranging from residential ground currents to magnetic field management.

A true expert system engine allows the user to ask questions about magnetic fields and then supplies them with answers. For instance you can ask specific questions such as how to measure magnetic fields in schools located in urban settings. The expert system also includes a very comprehensive glossary of EMF related terms.

RESICALC 2.1 - Models the magnetic fields from overhead transmission lines, distribution lines, and other user-defined conductors in residential and commercial areas. It also has the unique ability to automatically calculate net currents in the secondary and residential grounding system.

The CAD-like graphical user interface lets the user "draw" in the power lines using a mouse. A toolbar provides easy access to the drawing tools.

The data base, containing default configurations that can be modified by the user, supports multiple transmission line, distribution line, and grounding conductor configurations. 3-D maps and contour plots provide graphical results of the magnetic field calculations. Improvements over version 2.0 include color coded 3-D maps with contours, multiple levels of un-zoom, copying to the Windows® clipboard in metafile format, and support for multiple configuration databases.

SUBCALC 2.0 - Operationally similar to RESICALC, SUBCALC models the magnetic fields in and around transmission and distribution substations.

In addition to transmission lines, distribution lines, and underground cables, the user can "draw" in the substation equipment such as buses and circuit breakers. The top and side view perspectives allow drawing of conductors in three dimensions. In addition to the 3-D and contour maps, a profile plot shows the magnitude and phase angle of the magnetic field components along a user-defined traverse.

Improvements in version 2.0 include additional equipment models for power transformers, air core reactors/wave traps and capacitor banks. Other improvements include color coded 3-D maps with contours, multiple level un-zoom, support for multiple configuration databases and an edit box for modifying all of the nodes in a bus structure.

WINPLC. 1.12 - The Power Line Calculator computes various electrical components for one, two and three-phase power lines including neutral and ground currents. Symmetric components, power factor, apparent power, reactive power, phase current magnitude and angles, net phase current magnitude and angle, and neutral and ground current magnitude and phase angle are calculated. Given up to six input parameters, WINPLC will determine the remaining system variables. The data from the WINPLC can be transferred automatically into SUBCALC and RESICALC programs to save time and avoiding user input errors.

ENVIRO 3.5 - The ENVIRO module calculates lateral profiles for magnetic and electric fields as well as audible noise. The module has the unique ability to calculate induced current on shield wires. This new version has been improved to handle up to 50 conductor bundles (previous version would only accept 24) and it now reads TLWorkstation version input files. The interface has been upgraded and given a 3-D look and it now uses the Microsoft® Windows® common dialog boxes.

EXPOCALC 3.5 - The EXPOCALC module calculates electric and magnetic fields over a 2 dimensional area. It also computes exposure to electric and magnetic fields. It has the unique ability to perform electric field shielding calculations from objects such as transmission towers, buildings and trees.

This new version has been improved to handle up to 50 conductor bundles (previous version would only accept 24), the user interface has been upgraded and given a 3-D look and it now uses the Microsoft® Windows® common dialog boxes.

Future Modules - For the next release of EMFWorkstation (version 3.0) the RESICALC and SUBCALC modules will be merged into a single module. The program will retain all of the functionality of the current versions while adding new features.

The ability to calculate shielding from passive wire loops will be added as well as an improved version of the EMF Expert system that includes multimedia features such as animation, sound and video clips. Also, updated versions of selected EMFW 2.5 modules will be included.

Software Registration - A new form of software lock has been integrated into this version of EMFW. The software will run in a demo mode (can’t perform calculations or save files to disk) until it has been properly registered with EPRI and a valid unlock code has been entered.

The unlock code will provide access to the software for the remainder of the calendar year. It will automatically "time-out" on December 31 of each year at which time you must call in and re-register the software for another years worth of use. The software will revert back to demo mode until another valid unlock code is entered.

This software lock also prevents the software from being installed on multiple systems without calling in for an unlock code. EPRI is requiring this registration so it will have a record of end users who will need to be notified about EMFW updates and literature.


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