--- title: Vertical HOLLOSHAFT Motors with AEGIS description: US Motors WPI & CORRO-DUTY HOLLOSHAFT motors come with AEGIS Rings factory-installed to protect against electrical bearing damage. image: https://blog.est-aegis.com/hubfs/Imported_Blog_Media/holloshaft.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) # Vertical HOLLOSHAFT Motors with AEGIS [Home](https://www.est-aegis.com/) » [Blog](https://blog.est-aegis.com/) » Vertical HOLLOSHAFT Motors with AEGIS [AEGIS](https://blog.est-aegis.com/author/estaegis) Nov 10, 2021 US Motors is a leader in the vertical hollow shaft motor market. Their HOLLOSHAFT® Motors are ideal for use on turbine, mix flow, propeller, and other pumps.  And now, all of their Inverter Duty [Weather Protected Type I (WPI)](https://acim.nidec.com/motors/usmotors/~/media/USMotors/Documents/Catalogs/FL600/VHS-WPI-INV.ashx) and [CORRO-DUTY®](https://acim.nidec.com/motors/usmotors/-/media/usmotors/documents/literature/datasheets/product-data-sheets/pds_corro-duty-vhs-inverter-duty-stock-models.ashx) HOLLOSHAFT motors include AEGIS® Shaft Grounding Rings for electrical bearing protection. ![holloshaft](https://blog.est-aegis.com/hs-fs/hubfs/Imported_Blog_Media/holloshaft.jpg?width=201&height=275&name=holloshaft.jpg)WPI HOLLOSHAFT motors are constructed to minimize ingress of rain and snow, as well as dust and dirt.  And their ventilation system optimizes cooling of the thrust bearing and electrical components.  CORRO-DUTY motors have TEFC frames to prevent ingress and corrosion-resistant paint and hardware for extremely harsh environments. Inverter duty motors are designed to resist the side effects of variable frequency drive (VFD) control.  VFDs can cause electrical damage to both the stator windings and the bearings of the motors they control.  To protect the windings, these inverter duty motors include Class H Inverter Grade® insulation. VFDs produce voltage on the shafts of the motors they control, and this voltage can cause arcing through the bearings.  In larger motors, over 100 hp, drives also produce high-frequency circulating currents that go through both bearings at once.  All inverter duty WPI and CORRO-DUTY HOLLOSHAFT motors include an AEGIS Shaft Grounding Ring mounted inside, to discharge shaft voltage safely.  And those over 100 hp also include an insulated thrust bearing to block circulating currents. 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 with AEGIS Installed](https://blog.est-aegis.com/tag/motors-with-aegis-installed), [Vertical Motors](https://blog.est-aegis.com/tag/vertical-motors) ### Subscribe To Our Blog ## Read On ### [Permanent Magnet AC Motors Need Shaft Grounding](https://blog.est-aegis.com/permanent-magnet-ac-motors-need-shaft-grounding?hsLang=en-us) Permanent magnet ac (PMAC) motors are an increasingly popular substitute for induction motors. They... ### [Marathon Motors with Bearing Current Protection](https://blog.est-aegis.com/marathon-motors-with-bearing-current-protection?hsLang=en-us) In its long history, Marathon Motors has seen some changes. When they produced their first washing... ### [LEESON SyMAX Motors with AEGIS Inside](https://blog.est-aegis.com/leeson-symax-with-aegis?hsLang=en-us) Permanent magnet AC (PMAC) motors have many advantages over AC induction motors, including higher... [![Electro Static Energy](https://blog.est-aegis.com/hubfs/raw_assets/public/public/images/logo-est-alt.svg) ![AEGIS](https://blog.est-aegis.com/hubfs/raw_assets/public/public/images/logo-aegis-alt.svg)](https://www.est-aegis.com) 31 Winterbrook Road Mechanic Falls, ME 04256 Phone: [+1 207-998-5140](tel:+1%20207-998-5140) Fax: [+1 207-998-5143](fax:+1%20207-998-5143) Contact Us: [Send Message](https://www.est-aegis.com/contact/) ## Subscribe to Our Emails - [Products](https://www.est-aegis.com/products/) - [AEGIS® SGR](https://www.est-aegis.com/product/sgr/) - [AEGIS® uKIT](https://www.est-aegis.com/product/sgr-ukit/) - [AEGIS® PRO Series](https://www.est-aegis.com/product/pro-series/) - [Testing & Accessories](https://www.est-aegis.com/product/mounting-accessories/) - [Custom Static Solutions](https://www.est-aegis.com/product/custom-static-solutions/) - [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](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/) - [Resources](https://www.est-aegis.com/resources/) - [Request a Training](https://www.est-aegis.com/contact/request-a-training/) - [AEGIS® Bearing Protection Handbook](https://www.est-aegis.com/resources/handbook/) - [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/) - [Product Sheets](https://www.est-aegis.com/resources/product-sheets/) - - - Copyright 2022 Electro Static Technology. All rights reserved. Made in America. - [Privacy Policy](https://www.est-aegis.com/privacy-policy/) - [Terms and Conditions](https://www.est-aegis.com/terms-and-conditions/) - [Sitemap](https://www.est-aegis.com/sitemap/)