Equipotential Conflict - SOLIDWORKS Electrical Design Rule Checks Pt 2

By Joe McDiarmid

This is part 2 of our Design Rule Checks (DRC) blog series covering Equipotential Conflict. You can find part 1 here.

Ask yourself, have you ever accidentally crossed a pair of wires that shouldn't have been? It isn't pretty. It usually involves some sparks, and if you’re lucky some smoke and fire to go along with it. If you’re exceedingly lucky, you can also get a little zap that makes your arm tingle without the pesky side effect of death. While most of us deal with relatively low voltage devices in our daily lives, in manufacturing and other industries electrical systems can run on high voltages and in cramped, cluttered spaces. Schematics with errors, inconsistencies, poorly documented drawings or From-To lists are not just an annoying drain on productivity and a waste of money, but potentially a matter of life and death.

The Equipotential Conflict DRC scans for and displays error symbols on any wires that appear to be continuous or connected in the schematic, but have different equipotential values. An “equipotential” is simply looking at the relative voltage level of a section of the circuit in comparison to other sections separated by electrical parts/components, connectors, splices, etc. It is not attempting to calculate an actual predicted voltage value for any section, but simply comparing the section relative to another based on the predicted effect a component or connection will have between the sections.

 

For example, splicing two wires together with a barrel splice (ideally) will not affect the voltage of the wires on either side of the splice, but putting a resistor between two wires ensures a different voltage level on either side of the resistor. In the former example, the software assigns all the wires off the splice with the same equipotential value, an integer number that identifies the “level” that those wires occupy voltage-wise. In the latter example, the wires on either side of the resistor will have different equipotential values assigned, because the software is predicting that there will be a voltage drop, and therefore an equipotential difference, on either side of that component.

 

 

Sometimes, wires that definitely should not have the same equipotential value end up with that assignment anyway. This can lead to a condition that Industry Experts refer to as “Electrical Gremlins”, who are known for mysteriously starting fires and zapping people. Sources of error include wires whose equipotential value are manually overridden or wires accidentally spliced together with mis-matched wire styles or equipotentials. If the Equipotential Conflict DRC is not active or the symbol for the DRC check is not enabled, it is possible to make mistakes with respect to equipotential and not know it. You could for example, draw a wire between two unlike styles by accident, creating a bridge or short where you did not intend to. An error like this, if allowed to persist to production, could potentially lead to serious damage to the system or injury to workers.

To activate the Equipotential Conflict DRC in SOLIDWORKS Electrical  you must enable the symbol as well as generate the report. The report lists in a table all the wires with errors and their locations in the project, while the symbol is dynamic and will appear anytime a violation of the equipotential rule is established, and remain there until it is fixed.

To enable the symbol, click on the Project tab and click on the Configurations drop down arrow and select Project. In the “Project Configuration” window, choose the Graphic tab at the top of the window, and verify that the “Equipotential Conflicts” display checkbox is marked, as shown below.

 

To activate the DRC report, click on the Project tab and in the far right section titled “Reports” is the Design Rule Check icon. Click it and click Add in the upper left corner of the “Design Rules Manager” window. Find the “Equipotentialconflict_Metric” (or “_Imperial” depending on the projects units) report and make sure that the check box is filled. Click OK and then Generate Drawings in the “Design Rules Manager” window. Again make sure the checkbox for “Equipotential Conflicts” is checked, and click OK.

The software will scan the schematics for any wires that are connected together with mismatched equipotentials, display a symbol on the wires in violation of the DRC, and generate a table report in the document list that can be used as a record of the edits made, or deleted once the wires are corrected. By making sure there are no Equipotential violations, we can be reasonably assured that no one will be accidentally shocking themselves or starting a fire when they put current through the system for the first time.

Watch the video below for a look, and be sure to check out all of the DRC videos on our YouTube channel.