Baldor/EST alliance aims for mastery of food-safe stainless steel motors
Electro Static Technology's AEGIS shaft grounding rings now come standard on the furthest developed models in Baldor's food-safe stainless steel line of motors, per a recent update from the Mechanic Falls, Maine company and its partner in Fort Smith.
The patented rings "have been made standard equipment on the Baldor-Reliance Food Safe line of motors," the company said in an e-mail to Electrical Apparatus last week, adding that "the addition of the internal shaft grounding ring provides increased motor reliability and stops early bearing failure from EDM."
Washdown motors in a dairy plant.—JE Bearing & Machine photo
The Baldor food-safe line applicable here consists of 25 models with horsepower ratings from ½ HP up to 10 HP. They are often considered ideal for food processing, high pressure washdown, sanitary washdown, outdoor or caustic environment applications. A primary reason cited for this integration, according to AEGIS, is to mitigate the effects of bearing currents caused by variable frequency drives (VFDs).
When VFDs are used to control AC motors, voltage is induced on the motor shaft. This voltage builds up until it is strong enough to discharge by arcing through the bearings, causing frosting, pitting, fusion craters, and fluting. Over time, this bearing current causes premature bearing failure.
The rings can protect motors by channeling VFD-induced bearing current safely to ground. "Continuous circumferential rows of conductive microfibers, embedded securely in the ring’s patented AEGIS ® FiberLock channel, completely surround the motor shaft and provide millions of discharge points for harmful shaft voltage," EST says in a related press release. "This unique design creates the path of least resistance that effectively diverts current away from the bearings to ground. The microfibers themselves are specially engineered for exceptional conductivity and flexibility to minimize wear and prevent breakage."
AEGIS bearing protection is available on motors from most leading manufacturers and can be specified at the time of purchase. Motors can also be retrofitted either in the field or at motor repair shops.