--- title: What are Motor Repair Best Practices for VFD-Driven Motors description: Motors operated by variable frequency drives (VFD) are vulnerable to premature bearing failure from VFD induced shaft voltages and bearing currents – sometimes within only weeks or months – and the re image: https://blog.est-aegis.com/hubfs/Imported_Blog_Media/Picture1-e1527100456420.png --- [![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) # Motor Repair Best Practices for VFD-Driven Motors [Home](https://www.est-aegis.com/) » [Blog](https://blog.est-aegis.com/) » Motor Repair Best Practices for VFD-Driven Motors [AEGIS](https://blog.est-aegis.com/author/estaegis) May 23, 2018 Motors operated by variable frequency drives (VFD) are vulnerable to premature bearing failure from VFD induced shaft voltages and bearing currents – sometimes within only weeks or months – and the result is costly down time and production interruptions. Avoiding these costs makes economic sense and pays a high return on investment. ### [VFD-Driven Motors Can Fail From Destructive Bearing Currents - Costing Downtime and Lost Production](https://www.est-aegis.com/markets/motor-repair.php) [![ANSI/EASA Standard AR100-2015](https://blog.est-aegis.com/hs-fs/hubfs/Imported_Blog_Media/Picture1-e1527100456420.png?width=700&height=112&name=Picture1-e1527100456420.png) ![Motor Repair Best Practices](https://blog.est-aegis.com/hs-fs/hubfs/Imported_Blog_Media/Motor-repair_Page_1-2-308x1024.jpg?width=308&height=1024&name=Motor-repair_Page_1-2-308x1024.jpg)](https://www.est-aegis.com/markets/motor-repair.php)VFDs induce destructive shaft voltages and high-frequency currents which will cause electrical discharge machining (EDM) pitting, fusion craters, and fluting damage to the motor’s bearings and deteriorate the bearing lubrication by allowing electrical arcing to burn the grease. #### Cost Avoidance - Follow Best Practices to Ensure Up-time and Reliability Motor repair best practices will provide bearing protection from these destructive bearing currents by adding AEGIS® Shaft Grounding Ring Technology and, when needed, insulating a bearing to prevent high frequency circulating currents. - Motors up to 100 HP - Add AEGIS Shaft Grounding Ring to discharge shaft voltages to ground. - Motors over 100 HP - Add AEGIS Ring at one end and insulate the bearing at the opposite end. - Detailed recommendations are contained in the [AEGIS Bearing Protection Handbook](https://www.est-aegis.com/resources/handbook/). #### Motor Bearings are the Most Vulnerable Parts and the Cost of a Failed Motor Adds Up Quickly #### ![Failed motor costs](https://blog.est-aegis.com/hs-fs/hubfs/Imported_Blog_Media/Motor-repair_Page_1-3-300x162.jpg?width=300&height=162&name=Motor-repair_Page_1-3-300x162.jpg) The return on investment in repairing motors and following the AEGIS Bearing Protection Handbook’s best practices recommendations will pay dividends day after day and ensure the most reliable repair to the motor.   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) [Shaft Grounding Rings](https://blog.est-aegis.com/tag/shaft-grounding-rings), [Variable Frequency Drive](https://blog.est-aegis.com/tag/variable-frequency-drive), [Electrical Bearing Damage](https://blog.est-aegis.com/tag/electrical-bearing-damage), [AEGIS PRO Rings](https://blog.est-aegis.com/tag/aegis-pro-rings), [Best Practices](https://blog.est-aegis.com/tag/best-practices), [Motor Repair](https://blog.est-aegis.com/tag/motor-repair), [Bearing Protection](https://blog.est-aegis.com/tag/bearing-protection) ### Subscribe To Our Blog ## Read On ### [Industrial Motor Maintenance Challenges: Addressing Common Causes of Unplanned Downtime](https://blog.est-aegis.com/industrial-motor-maintenance-challenges-prevent-unplanned-downtime?hsLang=en-us) *(Industrial Motor Maintenance Challenges — Series Kickoff)* ### [How AEGIS Shaft Grounding Rings Reduce Risk in Electric Motor Systems](https://blog.est-aegis.com/electric-motor-reliability-with-aegis-shaft-grounding-rings?hsLang=en-us) Electric motor systems are the backbone of countless industries, from manufacturing to utilities.... ### [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,... 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