New Motor Grounding Seal Prevents Shaft Current From Damaging AC Motor Bearings, Increases Productivity And Reliability, Eliminates Catastrophic Motor Failure

Rock Island, IL (PRWEB) July 27, 2005

Inpro/Seal has announced their Motor Grounding Seal (MGS), an innovative bearing isolator/grounding seal that stops the damaging effects from destructive residual shaft currents on AC motors. Specifically developed for VFD controlled AC motor applications, it prevents pitting, fluting, fusion craters and eliminates catastrophic motor failure while permanently protecting bearings from contamination.


The Use Of Variable Frequency Drives


A VFD works by electronically matching the mechanical output of the motor to the exact application. Once the load is precisely matched, the speed is adjusted and the motor produces only the amount of energy needed. Equipment operates at capacity, runs more efficiently, energy consumption is lowered and operating costs are reduced. Experts agree that the use of variable-speed control on motors and other types of rotating equipment can save a significant amount of money from improved efficiencies and increased production.


The Damaging Effects Of Bearing Current


Inherently, the VFD system generates residual current or shaft voltage that accumulates on the rotor and discharges (shaft to frame) through the motor bearing. Causes of this resultant bearing damage range from voltage pulse overshoot and non-symmetry of the motor’s magnetic circuit to power unbalances, transient conditions and other conditions that work together or independently to create damaging currents.


This random and frequent discharging is referred to as the EDM effect. An acronym for electric discharge machining, this phenomenon causes pitting on the bearing’s rolling elements and raceways. At first, these EDMs create a frosted or sandblasted effect. Over time this deterioration causes fluting – a groove pattern in the bearing race that leads to destructive bearing failure.


Passive Fixes Do Not Last


Before the advent of the MGS Grounding Seal, a number of methods were tried to minimize the damaging effects of shaft currents, including: shaft grounding; external brushes; ceramic bearings; conductive greases and insulated bearings. The problem is that these are passive methods that are not cost effective, do not last, allow currents to continue to build up, require continual maintenance, allow for contaminants to accumulate and in some cases and can actually interfere with motor performance. Moreover, because many of these methods appear to be effective, unless there was a catastrophic bearing failure, there was no way to tell if they were working.


Enter The MGS Seal


Fortunately these problems can be solved and breakdown eliminated with the Inpro/Seal Motor Grounding Seal, an enhanced bearing isolator that prevents electrical damage to AC motor bearings by safely diverting harmful residual shaft currents.


The result of ongoing R & D, extensive field testing and exhaustive trials in their dedicated testing facility, along with the combined efforts of Electro Static Technology, the MGS Bearing Isolator eliminates this damaging shaft current by providing a “virtual short” between the shaft and motor frame that keeps shaft current and voltage from building up before bearing damage can occur.


MGS Seal Is Based On Highly Successful Product


At the heart of the MGS is an Inpro/Seal bearing isolator, a compound labyrinth bearing protection device, that Inpro invented (and patented) in 1977 and have now modified it for use with AC Motor applications.


A major innovation is a unique design that includes a grounding ring and brush built into the bearing isolator. The grounding ring dissipates the current and gives it a path to ground, away from the bearings. The brush contains microfibers that completely surround the shaft that work to discharge shaft current. The highest levels of performance are further assured by virtue of an inherent non-contact design that provides a life-time seal against, dust, liquids and other contaminants.


Simple, Low Cost, Long Term Fix


The MGS Motor Grounding Seal is a low cost solution that requires no maintenance and without the need for any adjustments. With no moving parts, dramatically increased life cycles are assured. It installs with a simple press fit to the internal or external motor housing. As the frame connection is part of the press fit, no external wiring is required.


Long Involvement In Rotating Equipment


According to David C. Orlowski, President of Inpro/Seal, the holder of some 40 patents and considered by many as the “father” of bearing isolation technology, “For over three decades Inpro/Seal has been on the cutting edge of sealing, process and bearing technology. And with almost two million bearing isolators installed, we are experienced in finding solutions to the most demanding problems. More importantly, our R & D people are constantly searching for ways to help end users increase productivity.”


Orlowski continued, “In reality, when it comes to a failed motor, the expense of the repair or replacement is a minor cost. With plant downtime running as high as $ 80,000 per hour, the real cost is in the downtime, labor, loss of production and disruption of production schedules. With this as a background, Electro Static Technology, the world leader in shaft grounding, conductive technology and Inpro/Seal, the world leader in bearing protection joined forces to develop the MGS Bearing Isolator. There is nothing else like it on the market.”


Two Global Leaders


Headquartered in Mechanic Falls, Maine, Electro Static Technology is a recognized global leader in the elimination and/or mitigation of induced electrical charges. They also engineer flexible peel-and-stick passive static eliminators for printers, copiers and other imaging devices.


Inpro/Seal Company is the world’s largest manufacturer of bearing isolators. The bearing isolator that they invented (patented back in 1977), known as an Inpro/Seal, has become a generic name in bearing protection. A non-contact, non-wearing, labyrinth permanent bearing protection device, the bearing isolator has two parts, a stator that presses into the bearing housing and a rotor that turns with the shaft. The two components interact to keep contamination out of the bearing enclosure and the lubricant in.


About Inpro/Seal


Inpro/Seal Company is the originator and the world’s number one manufacturer of bearing isolators, used to protect motor and pump bearings, machine tool spindles, turbines, fans, gear boxes, paper machine rolls and many other types of rotating equipment. Additional applications include the sealing, handling, processing of dry particulates, powders and bulk solids.


Over one and one half million of Inpro/Seal’s original bearing isolator designs are in operation in process plants worldwide, where end users continue to report significantly reduced operating costs with increased productivity and reliability. Documented cases show that a plant can more than double the mean-time-between failure (MTBF) and reduce maintenance costs by at least half, with users reporting an extremely high ROI.


As the recognized global leader in bearing isolator technology, Inpro products are marketed to the aerospace, automotive, petroleum, refining, nuclear, power generation, metalworking, food processing, grain processing, chemical, water, wastewater treatment, metalworking, hydrocarbon processing, HVAC, pulp and paper, mining, mineral, ore processing and general industrial markets.


Industry Leading Web Support


When an end user visits or they will find a wealth of information related to Inpro/Seal and bearing protection, including: specific applications, case histories, data sheets, facts and questions, specifications and more. Interactive spreadsheets include a Cost Justification Worksheet, that quantifies the effectiveness of bearing isolators in rotating equipment and a Contact Seal Energy Consumption Calculator that reveals the true cost of contact seals.




For more information on the Inpro/Seal Motor Grounding Seal (MGS). including a FREE brochure, contact Terri Hageman at: Inpro/Seal Company, P.O. Box 3940, Rock Island, Illinois 61204. Phone numbers are: (800) 447-0524 or (309) 787-4971. Fax number is: (309) 787-6114. Website: or


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About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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