Series AC Inverters User's Manual

Section 5: RFI Suppression and XLF Line Filters5.5 Interference Suppression Measures(Electromagnetic Compatibility)Electrical/electronic devices are capable of inßuencing or disturbingeach other through connecting cables or other metallic connections.Electromagnetic compatibility consists of two elements: interferenceresistance and interference emission.Correct installation of the inverter in conjunction with any possiblelocal interference suppression measures has a crucial effect onminimizing or suppressing mutual interference.The following guidelines assume a power source that is notcontaminated by high frequency interference. Other measures may benecessary to reduce or suppress interference if the power source iscontaminated, and no general recommendations can be given for suchcases. Please consult TB WoodÕs Electrical Application EngineeringDepartment if the following recommended interference suppressionmeasures do not produce the desired result.When dealing with RFI (radio frequency interference), the surface areaof the conductors is a more critical consideration than its cross sectionalarea. Since high frequency interference does not ßow through the entirecross section of the conductor, but tends to stay toward its outer surface(skin effect), braided copper tapes of equal cross section should be used.The inverter and all components used for interference suppression,particularly the shield of the motor cable, should be connected over aslarge a surface area as possible when passing over metallic surfaces.Remove the paint from contact surfaces to ensure a good electricalconnection. See Figure 9 for recommended connection technique.A central grounding point should be used for interference suppression.Route the ground cables radially from this point, avoiding loops whichmay lead to interference.Paint/varnish removedShielded motor cableLarge contact area with shieldFigure 9: Recommended Connection Technique38© 1998 TB Wood’s All Rights Reserved