Insulated EZE-Sleeves® are used in some inverter or frequency drive motors. The insulating material on the sleeve prevents eddy currents from passing through the bearing and causing static arcing. They come as a kit with two insulating rings to place at the back end of the end bell and between the bearing and the bearing cap if one is part of the motor being worked on. They are available in cast iron or steel.
Variable frequency motors, “freak drives”, inverter motors; whatever you call them you know that bearings fail in them fairly quickly and that the culprit is static arcing. How can we guarantee that electrical current will not pass though an object? Why, insulate it of course.
We take the insulation of our sleeves very seriously and only provide the best possible coating for the task of protecting bearings from eddy current damage.
Listed here is information in regards to the physical properties of the electrically insulated coating we put on our sleeves:
Type: Electrical Grade Functional Epoxy Coating.
Tensile Strength: 7500 psi
Dielectric Strength: 800 volts/mil (can resist 800 volts per .001″ of coating thickness) and we apply a minimum of .005″ of coating to each sleeve (.005″ if coating is 4000 volts of resistance). That, again, is the minimum and the average is .007″ of coating (5600 volts of resistance). There is also the dielectric strength of the recommended retaining compound (loctite® 620) to consider as well, which can add another .005″ of insulation (test results coming soon)
Thermal Shock Resistance: passes 12 cycles (400F to -20G) and can run at 385F indefinitely.
Listed here are the physical properties of the recommended retaining compound (Loctite® 620) to be used with the insulated EZE-Sleeve®:
Shear strength: over 3800 psi up to 0.015″ diameter clearance
Temperature resistance: Maintains retaining properties up to 450F
The washers used inside the end bell and between the bearing cap and bearing are .062″ acetron.