Danfoss FC 300 Design Manual

Also see for FC 300: Operating instructions Instruction manual Design guide Design guide Design guide

Contents

Danfoss FC 300 Design Manual Manual pdf 126 page image

• Keep the motor cable as short as possible to reduce the noise level and leakage currents.• Connect the motor cable shield to both the decoupling plate of the FC 300 and to themetal cabinet of the motor.• Make the shield connections with the largest possible surface area (cable clamp). This isdone by using the supplied installation devices in the FC 300.• Avoid mounting with twisted shield ends (pigtails), which will spoil high frequency shield-ing effects.• If it is necessary to split the shield to install a motor isolator or motor relay, the shieldmust be continued with the lowest possible HF impedance.6.3.11. Electrical Installation of Motor CablesShielding of cablesAvoid installation with twisted shield ends (pigtails). They spoil the shielding effect at higher fre-quencies.If it is necessary to break the shield to install a motor isolator or motor contactor, the shield mustbe continued at the lowest possible HF impedance.Cable length and cross-sectionThe adjustable frequency drive has been tested with a given length of cable and a given cross-section of that cable. If the cross-section is increased, the cable capacitance - and thus the leakagecurrent - may increase, thereby requiring that the cable length is reduced accordingly.Switching frequencyWhen adjustable frequency drives are used together with sine-wave filters to reduce the acousticnoise from a motor, the switching frequency must be set according to the sine-wave filter in-structions in par. 14-01.Aluminum conductorsAluminum conductors are not recommended. Terminals can accept aluminum conductors, but theconductor surface has to be clean, oxidation must be removed, and the area must be sealed byneutral acid-free Vaseline grease before the conductor is connected.Furthermore, the terminal screw must be retightened after two days due to the softness of thealuminum. It is crucial to keep the connection a gas-tight joint, otherwise the aluminum surfacewill oxidize again.6.3.12. Switches S201, S202, and S801Switches S201 (A53) and S202 (A54) are used to select a current (0-20 mA) or a voltage (-10 to10 V) configuration for the analog input terminals 53 and 54, respectively.Switch S801 (BUS TER.) can be used to enable termination on the RS-485 port (terminals 68 and69).See drawingDiagram showing all electrical terminals in sectionElectrical Installation.Default setting:S201 (A53) = OFF (voltage input)S202 (A54) = OFF (voltage input)6. How to Install FC 300 Design Guide126 MG.33.B9.22 - VLT® is a registered Danfoss trademark.6