4.6 Motor CablesSee chapter 7.2 General Specifications for correctdimensioning of motor cable cross-section and length. Seechapter 4.10.1 EMC Emission for relationship betweenlength and EMC emission.Always comply with national and local regulations oncable cross-section.NOTICEIf an unscreened/unarmoured cable is used, some EMCrequirements are not complied with. Refer tochapter 4.10.1 EMC Emission for more details.To comply with the EMC specifications regarding emission,the motor cable must be screened/armoured, unlessotherwise stated for the RFI filter in question. It isimportant to keep the motor cable as short as possible soas to reduce the noise level and leakage currents to aminimum. Connect the motor cable screen to the metalcabinet of the frequency converter and to the metalcabinet of the motor. Make the screen connections withthe biggest possible surface area (cable clamp). This isenabled by different installation devices in differentfrequency converters. Avoid mounting with twisted screenends (pigtails), since these spoil the screening effect athigh frequencies. If it is necessary to break the screen toinstall a motor isolator or motor relay, the screen must becontinued at the lowest possible HF impedance.4.7 Motor Thermal ProtectionThe electronic thermal relay in the frequency converter hasreceived the UL-approval for single motor protection,when parameter 128 Motor thermal protection has been setfor ETR Trip and parameter 105 Motor current, IM, N has beenprogrammed to the rated motor current (see motornameplate).4.8 Control CablesRemove the front cover underneath the control panel.Place a jumper between terminals 12 and 27.Control cables must be screened/armoured. The screenmust be connected to the frequency converter chassis witha clamp. Normally, the screen must also be connected tothe chassis of the controlling unit (use the instructions forthe unit in question). In connection with very long controlcables and analog signals, in rare cases depending on theinstallation, 50/60 Hz ground loops may occur because ofnoise transmitted from mains supply cables. In thisconnection, it may be necessary to break the screen andpossibly insert a 100 nF capacitor between the screen andthe chassis.See section Grounding of Screened/Armoured control cablesin the Design Guide for the correct termination of controlcables.Illustration 4.8 Control Cable ConnectionElectrical Installation Quick GuideMG28M202 Danfoss A/S © Rev. 2014-03-18 All rights reserved. 134 4