In motors driven across-the-line, bearing failures can result from internally generated currents. Increased use of variable speed drives (VSDs) in electric motor applications also contributes to bearing current flow. When encoders are attached to motor shafts for feedback, eddy currents along the shafts can flow through the encoder bearings to ground, causing premature wear due to pitting.
Isolation inserts can prevent current flow through the encoder bearings, a common issue with inverter-controlled three-phase or AC vector motors. These currents significantly shorten encoder bearing service life. Additionally, the encoder can be thermally isolated, as the plastic insert does not conduct heat to the encoder.
To prevent premature encoder bearing failure, the encoder should be electrically isolated from the motor. The Kuebler 5020 hollow shaft encoder comes with optional insulating sleeves to achieve this. The anti-rotation torque arm, often used in motor applications, includes sliding insulated washers to isolate the encoder electrically from the motor body. Alternatively, an anti-rotation pin can prevent the encoder body from rotating.
The Kuebler 5020 encoder features patented dual SafetyLock bearings, a metal disk up to 1024 ppr, and a sturdy die-cast housing. Applications include construction cranes, construction equipment, machinery automation, and feedback on VFD motors to name a few.
Connectric Systems has significant expertise with encoders & automation, and can recommend options best suited for your application. Please contact us be email at sales@connectric.com or at 1-800-469-3342 (North America) or 1-905-669-0080