FC 300 Design GuideHow to Install" Use of EMC-Correct CablesDanfoss recommends braided shielded/armored cables to optimize EMC immunity of thecontrol cables and the EMC emission from the motor cables.The ability of a cable to reduce the incoming and outgoing radiation of electric noise dependson the transfer impedance (ZT ). The shield of a cable is normally designed to reduce thetransfer of electric noise; however, a shield with a lower transfer impedance (Z T ) value is moreeffective than a shield with a higher transfer impedance (Z T ).Transfer impedance (ZT ) is rarely stated by cable manufacturers but it is often possible to estimatetransfer impedance (Z T ) by assessing the physical design of the cable.Transfer impedance (Z T ) can be assessed on the basis of the following factors:- The conductibility of the shield material.- The contact resistance between the individual shield conductors.- The shield coverage, i.e. the physical area of the cable covered by the shield -often stated as a percentage value.- Shield type, i.e. braided or twisted pattern.a. Aluminum-clad with copper wire.b. Twisted copper wire or armored steel wire cable.c. Single-layer braided copper wire with varyingpercentage shield coverage.This is the typical Danfoss reference cable.d. Double-layer braided copper wire.e. Twin layer of braided copper wire with amagnetic, shielded/armored intermediate layer.f. Cable that runs in copper tube or steel tube.g. Lead cable with 0.043 in. (1.1 mm)wall thickness.122 MG.33.B6.22 - VLT is a registered Danfoss trademark
