--- title: Electrical Bearing Protection Questions and Answers | Part 22 description: Learn about grounding rings vs grounding brushes, welding, proper bonding of VFD cable shield, & specifying high-frequency grounding straps. image: https://blog.est-aegis.com/hubfs/c-brush-disp270x259.jpg --- [![Electro Static Technology](https://blog.est-aegis.com/hubfs/raw_assets/public/public/images/electro-static-technology.svg "Electro Static Technology")](https://www.est-aegis.com/) [![Aegis](https://blog.est-aegis.com/hubfs/raw_assets/public/public/images/Aegis.svg "Aegis")](https://www.est-aegis.com/) - [+1 866-738-1857](tel:+1%20866-738-1857) - [Products](https://www.est-aegis.com/products/) - [AEGIS® SGR – for motors under 500 HP/375 kW](https://www.est-aegis.com/product/sgr/) - [AEGIS® uKIT – for common NEMA/IEC frame size](https://www.est-aegis.com/product/sgr-ukit/) - [AEGIS® RPPR – for reactor recirculating pumps](https://www.est-aegis.com/rppr-resources/) - [AEGIS® EV and EVO Rings - for electric vehicles](https://www.est-aegis.com/product/ev-evo-rings/) - [AEGIS® PRO Series – for motors over 300 HP/225 kW](https://www.est-aegis.com/product/pro-series/) - [Shaft Voltage Testing and Accessories](https://www.est-aegis.com/product/mounting-accessories/) - [Online Product Catalog](https://catalog.est-aegis.com/) - [AEGIS® 2-Year Extended Warranty](https://www.est-aegis.com/product/extended-warranty/) - [Applications](https://www.est-aegis.com/applications/) - [Electric Vehicle Solutions](https://www.est-aegis.com/applications/electric-vehicle-solutions/) - [Food & Beverage](https://www.est-aegis.com/applications/food-beverage/) - [HVAC](https://www.est-aegis.com/applications/hvac/) - [Industrial & Chemical](https://www.est-aegis.com/applications/industrial-chemical/) - [Other Industries](https://www.est-aegis.com/applications/other-industries/) - [Power Generation & Renewable Energy](https://www.est-aegis.com/applications/power-generation-renewable-energy/) - [Transportation](https://www.est-aegis.com/applications/transportation/) - [Water Treatment](https://www.est-aegis.com/applications/water-treatment/) - [Bearing Protection](https://www.est-aegis.com/bearing-protection/) - [Shaft Voltage & Bearing Currents](https://www.est-aegis.com/bearing-protection/shaft-voltage-and-bearing-currents/) - [Fluting & Bearing Inspection](https://www.est-aegis.com/bearing-protection/fluting-and-bearing-inspection/) - [Best Practices & Installation](https://www.est-aegis.com/bearing-protection/best-practices-and-installation/) - [Resources](https://www.est-aegis.com/resources/) - [AEGIS® Bearing Protection Handbook](https://www.est-aegis.com/resources/handbook/) - [IEEE-841, Hazardous Locations, & AEGIS®](https://info.est-aegis.com/technical-codes-and-ieee-841-standards) - [Recorded Webinars Library](https://www.est-aegis.com/resources/recorded-webinars/) - [Installation Instructions](https://www.est-aegis.com/resources/installation-instructions/) - [Videos](https://www.est-aegis.com/resources/videos/) - [Technical Papers](https://www.est-aegis.com/resources/technical-papers/) - [Case Studies](https://www.est-aegis.com/resources/case-studies/) - [Specifying AEGIS®](https://www.est-aegis.com/resources/specifying-aegis/) - [Request Training](https://www.est-aegis.com/resources/training/) - [Product Sheets](https://www.est-aegis.com/resources/product-sheets/) - [About](https://www.est-aegis.com/about/) - [News](https://blog.est-aegis.com/) - [Tradeshows](https://www.est-aegis.com/about/tradeshows/) - [Blog](https://blog.est-aegis.com/) - [Where to Buy](https://www.est-aegis.com/where-to-buy/) - [Distributors](https://www.est-aegis.com/where-to-buy/distributors?type=Distributor) - [Trained Installers](https://www.est-aegis.com/where-to-buy/installers?type=Installer) - [Explosion Proof Installers](https://www.est-aegis.com/where-to-buy/installers?type=Explosion%20Proof%20Installer) - [Motors & Seals with AEGIS® Installed](https://www.est-aegis.com/where-to-buy/oems-with-aegis/) [Contact Us](https://www.est-aegis.com/contact/) - [+1 866-738-1857](tel:+1%20866-738-1857) # Electrical Bearing Protection Q&A – Part 22 [Home](https://www.est-aegis.com/) » [Blog](https://blog.est-aegis.com/) » Electrical Bearing Protection Q&A – Part 22 [AEGIS](https://blog.est-aegis.com/author/estaegis) Apr 4, 2022 **Q1.  What are the pros and cons of shaft grounding rings compared with shaft grounding brushes?** **![c-brush-disp270x259](https://blog.est-aegis.com/hs-fs/hubfs/c-brush-disp270x259.jpg?width=350&name=c-brush-disp270x259.jpg)A1.** Our understanding is that carbon block brushes wear a lot faster than our AEGIS® rings. There are some other factors, too, but these brushes have a couple of strengths. Carbon brushes can conduct dc current better than high-frequency ac current. These brushes have been used for over 100 years in dc motor commutators.  With grounding rings, it's the opposite. So you wouldn't want to use an AEGIS ring in a commutator.  But VFD-sourced shaft current is high-frequency, so AEGIS rings are the better fit there. There are also cases where you have dc/low-frequency and high-frequency current. So sometimes you want a carbon brush and an AEGIS ring. Wind turbine generators are a great example.  Neither a carbon brush nor a grounding ring alone is enough. But together, they can protect the generator bearings. **Q2.  Can a shaft grounding ring protect a motor from nearby welding?** **A2.** We wouldn't recommend it. Welding current can be hundreds of amps, continuously. Depending on the size of the rings, SGRs can handle up to 70 amps, and PRO rings up to 250, but those are peak ac current ratings, not continuous dc. **Q3.  If you use a shielded VFD cable, should the shield be attached to the grounding ring?** **A3.** No. When you use shielding, it should be connected with glands at the motor junction box and at the VFD. It's important to get this right because doing it wrong will lose most of the shielding's benefits.  There's more detail in [this](http://industrial.southwire.com/en/techblog/2017/01/03/terminating-vfd-cables/)blog post by Southwire. At any rate, you should always follow the drive manufacturer's instructions. **![hfgs-to-cage-disp270x216](https://blog.est-aegis.com/hs-fs/hubfs/hfgs-to-cage-disp270x216.jpg?width=350&name=hfgs-to-cage-disp270x216.jpg)Q4.  If we specify shaft grounding rings be used on VFD-controlled motors, do we also need to specify high-frequency grounding straps explicitly?** **A4.** Short answer: Yes, if you want HFGS to be installed. We recommend using HFGS to bond the motor and drive, and motor and load. But the grounding ring is more important. If the motor is well-grounded, you can usually get by without an HFGS. But there are cases where you definitely want to use at least one. In those cases, you need to specify them explicitly. AEGIS Rings also come with a [2-year extended warranty](https://www.est-aegis.com/product/extended-warranty/) against bearing fluting damage. No other form of protection against VFD-caused bearing damage offers a warranty like this. [![2-Year Extended Warranty](https://no-cache.hubspot.com/cta/default/20974229/3b258d08-3058-4c7f-a866-2991b627f2e0.png)](https://cta-redirect.hubspot.com/cta/redirect/20974229/3b258d08-3058-4c7f-a866-2991b627f2e0) To learn more about AEGIS shaft grounding and best practices for electrical bearing protection, [sign up for a training](https://www.est-aegis.com/resources/training/). We offer monthly live training webinars, and we can also visit your facility to review your exact application. [![Sign Up For Training](https://no-cache.hubspot.com/cta/default/20974229/69dd56c7-bbd1-4ad0-ae5c-29de322039f0.png)](https://cta-redirect.hubspot.com/cta/redirect/20974229/69dd56c7-bbd1-4ad0-ae5c-29de322039f0) [Motors on VFD](https://blog.est-aegis.com/tag/motors) ### Subscribe To Our Blog ## Read On ### [Electrical Bearing Protection Q&A Part 5](https://blog.est-aegis.com/electrical-bearing-protection-qa-part-5?hsLang=en-us) Part 5 in a series of questions and answers from our Q&A [webinars](https://www.est-aegis.com/resources/training/). ### [Electrical Bearing Protection Q&A - Part 18](https://blog.est-aegis.com/electrical-bearing-protection-qa-part-18?hsLang=en-us) Part 18 in a series of questions and answers from our Q&A **[webinars](https://www.est-aegis.com/resources/training/)**. ### [Electrical Bearing Protection Q&A - Part 30 Grounding Rings and Brushes](https://blog.est-aegis.com/electrical-bearing-protection-qa-part-30?hsLang=en-us) Q1. What are the pros and cons of using a shaft grounding ring, as opposed to a shaft grounding... 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