--- title: How to Protect Pumping Systems on VFD description: When pump motors are run by variable frequency drives, their bearings are at risk of electrical bearing damage. Here is how to protect them. image: https://blog.est-aegis.com/hubfs/Imported_Blog_Media/blueash-21-300x225.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) # Pumping Systems on VFD Need Bearing Protection [Home](https://www.est-aegis.com/) » [Blog](https://blog.est-aegis.com/) » Pumping Systems on VFD Need Bearing Protection [AEGIS](https://blog.est-aegis.com/author/estaegis) Aug 22, 2023 ![blueash-21](https://blog.est-aegis.com/hs-fs/hubfs/Imported_Blog_Media/blueash-21.jpg?width=300&height=225&name=blueash-21.jpg)In most pump applications, running the pump at full speed is not always necessary.  Flow rate has traditionally been decreased with flow control valves, but this has disadvantages.  Nowadays, the flow is often controlled by running the pump’s motor on a variable frequency drive (VFD). Besides well-controlled flow rates, VFDs offer: • Energy savings (from reduced motor speeds) • Improved seal and impeller life and reduced vibration and noise (from reduced pressure) • Greatly reduced water hammer (from smooth acceleration and deceleration) But VFDs have their own downsides.  One big problem is that they create stray voltage on the motor shaft.  This shaft voltage can cause electrical damage to motor and pump bearings by discharging (arcing) through them.  This electrical damage accrues over time, causing premature bearing failure. The solution is to electrically bond the shaft to the motor frame with a [shaft grounding device](https://www.est-aegis.com/).  This gives charge on the shaft a low-resistance path to ground, so current flows through the grounding device instead of arcing through the bearings.  (Large motors, over 100 hp/75 kW also require one insulated bearing to prevent circulating VFD-induced currents.) AEGIS® Shaft Grounding Rings are the most reliable form of shaft grounding available.  AEGIS rings can be installed on existing motors, and several manufacturers also offer motors with AEGIS rings factory-installed, including vertical hollowshaft, severe duty, and even explosion-proof models. To learn more about the problem of VFD-induced bearing currents and the solution using AEGIS rings, see these [case studies](https://www.est-aegis.com/resources/case-studies/) and [best practices](https://www.est-aegis.com/bearing-protection/best-practices-and-installation/), or see the AEGIS [Youtube channel](https://www.youtube.com/channel/UCLbnVQas0tkhxFtH1bgc9fw). 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 - pandemic restrictions permitting - 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) \* *Image: AEGIS rings being installed on pump motors at Blue Ash Recreation Facility in Blue Ash, OH* [Bearing Currents](https://blog.est-aegis.com/tag/bearing-currents), [Motors on VFD](https://blog.est-aegis.com/tag/motors), [Pumps](https://blog.est-aegis.com/tag/pumps) ### Subscribe To Our Blog ## Read On ### [3 Factors to Consider With Bearing Performance](https://blog.est-aegis.com/what-are-the-factors-that-affect-bearing-performance?hsLang=en-us) Bearings are an integral part of electric motors. Designed not only to support the rotor, they help... ### [Protecting VFD-driven Motors in Plastics Production](https://blog.est-aegis.com/protecting-vfd-driven-motors-in-plastics-production?hsLang=en-us) Today, there are hundreds of types and blends of plastics, and they can be formed, molded,... ### [Prevent Downtime with Electrical Bearing Protection](https://blog.est-aegis.com/prevent-downtime-with-electrical-bearing-protection?hsLang=en-us) More and more electric motors are being controlled by variable frequency drives (VFDs). VFDs offer... 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