Protecting VFD-Driven Motors In Ski Resorts

Ski resorts use tremendous amounts of energy in their day-to-day operations.  All ski resorts must transport skiers from the base of a mountain to its peaks or to the start of various slopes or trails, without skiliftjerkiness.  To improve control of lift operations, many resorts are installing variable frequency drives (VFDs).  VFDs can smoothly adjust the speed of chair lifts, gondolas, carpets, and high-capacity trams to accommodate varying passenger loads, weather conditions, and other factors.  In addition to giving precise control, these drives can also save energy when they run snowmaking pumps or HVAC equipment.

For most ski resorts, lift and snowmaking operations account for more than 80% of total energy costs.

Although VFDs can yield smooth operation and energy savings, they can also damage the motors they control.  They create stray voltages on motor shafts, and this voltage can discharge by arcing through the bearings.  These arcs cause pitting, fluting, and eventually premature failure.  Without bearing protection, the benefits from of VFDs can be canceled by the high costs of downtime and motor repair/replacement.

AEGIS® Shaft Grounding Rings solve this problem by providing a low-resistance pathringse from the motor shaft to the frame.  So shaft voltage discharges through the AEGIS ring, instead of through the bearing.  This protects the bearings and motor against premature failure and protects the user from the costs of downtime and motor repair or replacement.  (Larger motors also require one insulated bearing, to protect against the second cause of electrical bearing damage.)

AEGIS rings can easily be mounted on in-service motors.  They're also available factory-installed on hundreds of motors from manufacturers like Baldor/ABB, Marathon, WEG, US Motors, and more.  You can search all motors with AEGIS at


AEGIS Rings also come with a 2-year 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

To learn more about AEGIS shaft grounding and best practices for electrical bearing protection, sign up for a 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