Poor grounding contributes to unnecessary downtime, but a lack of good grounding is dangerous and increases the risk of equipment failure. Without an effective grounding system, you could be exposed to the risk of electric shock, not to mention instrumentation errors, harmonic distortion issues, power factor problems and a host of possible intermittent dilemmas. If fault currents have no path to the ground through a properly designed and maintained grounding system, they will find unintended paths that could include people.
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Selective testing is very similar to the Fall-of-Potential testing, providing all the same measurements, but in a much safer and easier way. This is because with Selective testing, the earth electrode of interest does not need to be disconnected from its connection to the site! The technician does not have to endanger himself by disconnecting ground, nor endanger other personnel or electrical equipment inside a non-grounded structure.- The Fluke 1625 earth ground tester is able to measure earth ground loop resistances for multi-grounded systems using only current clamps. This test technique eliminates the dangerous, and time consuming activity of disconnecting parallel grounds, as well as the process of finding suitable locations.
Soil Resistivity Measurement- Fall-of-Potential Measurement
- Grounding Basics
- Measuring Ground Resistance
This issue of "Solid Ground" talks about ground fault circuit interrupters (GFCIs), why they are necessary, and how to troubleshoot GFCI-protected circuits.
All mine sites have grounded electrical systems, so that in the event of a lightning strike or utility overvoltage or ground fault, the current would be able to find a safe path to earth or the neutral of the transformer.
- As I promised in my last column, this "Solid Ground" column deals with transformers and grounding. Let's start by addressing some definitions. Opinions differ on the "official" definition of "distribution" transformer.
Normal earth ground measurement involves disconnecting parallel grounding rods, "planting" several auxiliary grounding stakes, and using a earth ground tester to calculate the resistance of grounding system electrodes. Sometimes, though, there isn't anywhere to plant the grounding stakes - such as inside a building, at a cell phone substation, or on power pylons. What then?
Reassessing airport tower lightning protection systems with checklist for ensuring reliable lightning protection, with aid of ground resistance
Expert, Chuck Newcombe, revisits techniques from 1963 for testing the electrical bonds in a grounding system and compares them with today's tools and methods.
Earth ground testing definitions and methods: grounding and bonding, purpose of the earth ground, Fall of Potential test, stakeless ground testing
