Here’s what more than 2,500 business decision-makers around the world say.Download the report
...with the Facility Hero app in hand! Discover how you can optimize your maintenance efforts today.Learn more
Access tailored services, 24/7 self-service and expert help. Anywhere, anytime, any project.Discover now
Everything you need to know about our IoT technology backbone.Learn more
Explore our global offerings or select your country from one of our five regions.Global
Découvrez nos offres globales ou sélectionnez votre pays dans l’une de nos cinq régions.
Measuring ground faults (This article will work for WYE systems only; you may reference RESL190365 for DELTA systems)
Many causes including shorts and power quality instances
There are two ways to measure ground faults.
1. Measure the neutral point of the WYE side of the transformer
2. Measure the sum of all the currents.
Below is a diagram that might help explain an application of V4. The V4 PT ratio can be set independently. It may be that no PT is necessary (i.e. 1:1) because the voltage will likely be fairly small. If the transformer star-point is resistance grounded a much larger voltage would develop across the grounding resister during a ground fault. The customer should do the calculation to determine what the maximum expected voltage might be.
-V4 measures the star point (neutral) voltage with respect to ground.
-During a phase to ground fault, depending on the transformer MVA and star point to ground resistance, V4 may be a few tens of voltage.
-More effective for resistance-grounded transformer secondary applications
In an ideal situation the sum of the currents will equal the phase currents. But in the case of a ground fault they are different. In order to see if the summation is different, the diagram below can be used to measure the sum of the currents and that sum will be displayed in I4.
Sign up for all the latest solutions, offers and best practices straight to your inbox.
We are excited that you have joined the group. You will receive your welcome email soon describing the program and what to expect in the upcoming weeks. Enjoy!