Improving Reliability of Servo Motors and VFD with Motor Filters

The biggest EMI-related issue in motion control is damage to the motor bearings caused by excessive high-frequency currents flowing through them. All pulse-width driven motors suffer deterioration of bearings (often called EDM - electric discharge machining). This article describes the problem in details.

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No Mechanical Fitting, No Wear, No Maintenance

OnFILTER' patent-pending SF-series dedicated dV/dt servo and variable-frequency drives (VFD) filters transform sharp edges of drive pulses into much less "polluting" gradual ramps and also provide additional filtering in motor's ground reducing current through bearings typically 80 to 100 times.  

Measured with Tektronix' CT1 probe 5mV/mA

No filter

SF-Series filter

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The SF-series filters connect between the controller and motor and require no mechanical fitting and no maintenance.  Information on SF-series filters can be found here.  If for whatever reason the motor filtering cannot be applied, our ground EMI filters connected between the controller and a motor can significantly reduce ground current by itself.

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Servo and variable-frequency motors often cause equipment errors due to excessive EMI.  Servo filter or, depending on a situation, ground filter may help to reduce this interference.