VLT ® 2000 Series Special conditions I Earthing The following basic issues need to be considered when installing a frequency converter, so as to obtain electromagnetic compatibility (EMC). A flat conductor, for example, has a lower HF impedance than a round conductor for the same con- ductor square value. If more than one applicance is installed in cabinets, the cabinet rear plate, which must be made of metal, should be used as a common earth reference plate. The metal cabinets of the different appliances are mounted on the cabinet rear plate using the lowest possible HF impedance.
This avoids having different HF voltages for the individual appliances and avoids the risk of radio interference currents running in connection cables that may be used between the appliances. The radio interference will have been reduced. Safety earthing: Safety earthing: Safety earthing: Safety earthing: Safety earthing: Please note that the frequency converter has a high leakage current and must be earthed appropriately for safety reasons. Apply local/national safety regulations. Use terminal 95 for reinforced earthing. High fr High fr High fr High fr High frequency earthing equency earthing equency earthing equency earthing equency earthing:
Keep the earth wire connections as short as possible. Connect the different earth systems at the lowest possible conductor impedance. The lowest possible conductor impedance is obtained by keeping the conductor as short as possible and by using the greatest possible surface area. I Cables The control cable and the filtered mains cable should be installed separately from the motor and brake cables to prevent interference coupling. Normally, a distance of 20 cm will be sufficient, but it is recommended to keep the greatest possible distance wherever possible, especially where cables are installed in parallel over a substantial distance. cable).
It must be pointed out that the necessary di- stance depends on the sensitivity of the installation and the signal cables, and that therefore no precise values can be stated. If cable trays are used, sensitive signal cables are not to be placed in the same cable trays as the motor cable or brake cable. If signal cables are to cross power cables, this should be done at an angle of 90 degrees. Remember that all interference-carrying in- or outgoing cables to/from a cabinet should be screened or filtered.
With respect to sensitive signal cables such as telephone cables and data cables, the greatest possible distance is recommended with a minimum of 1 per 5 m of power cable (mains, motor and brake The cables must throughout their length be reinforced/double-isolated to other cables. 88 MG.20.B6.02 – VLT is a registered Danfoss trademark