Danfoss VLT FCD 311 Design Manual

Also see for VLT FCD 303: Operating instructions

Contents

Danfoss VLT FCD 311 Design Manual Manual pdf 32 page image

VLT® FCD Series General information about electrical installation High voltage warningThe voltage of the frequency converteris dangerous whenever the equipment isconnected to mains.Incorrect fitting of themotor or frequency converter may cause damage tothe equipment, serious injury or death. Conse-quently, the instructions in this manual, as well asnational and local rules and safety regulations mustbe complied with.Touching the electrical parts may be fatal- even after the equipment has been disconnectedfrom mains: Wait at least 4 minutes.NB!:It is the user’s or fitter’s responsibility toensure correct earthing and protection in ac-cordance with national and local standards. EarthingThe following basic points must be considered at in-stallation:• Safety earthing: Please note that the frequencyconverter has a high leakage current and mustbe earthed appropriately for safety reasons. Ap-ply local safety regulations.• High frequency earthing: Keep earthing cables asshort as possible.Connect the different earthing systems, thereby en-suring the lowest possible conductor impedance.The lowest possible conductor impedance isachieved by keeping the conductor as short as pos-sible and by using the greatest possible surfacearea. A flat conductor, for example, has a lower HF-impedance than a round conductor, calculated forthe same conductor cross-section C VESS . If severalunits are installed on a common metal structure, itshould be used as a joint earth reference plate. Themetal cabinets of the different units must be fitted tothe metal structure at the lowest possible HF-impedance. With this feature, different HF-voltageswill not arise in different units, and there will be nonoise currents in cables used to connect units.Noise radiation will be reduced. In order to achievea low HF-impedance, the fastening bolts of the unitscan be used as HF-connection to the metal struc-ture. It is necessary to remove any layers of isolatingpaint or similar from the attachment points. CablesThe control cable and the mains cable should be in-stalled separately from motor cables to prevent noisetransfer. As a rule a distance of 20 cm is sufficient,but it is recommended that the distance is as greatas possible, particularly when cables are installed inparallel over large distances.For sensitive signal cables such as telephone ordata cables the greatest possible distance is recom-mended. Please note that the required distancedepends on the installation and the sensitivity of thesignal cables, and that for this reason exact valuescannot be given.When being placed in cable trenches, sensitive ca-bles may not be placed in the same cable trench asthe motor cable. If signal cables run across powercables, this is done at an angle of 90 degrees. Re-member that all noise-filled inlet and outlet cables toa cabinet must be screened/armoured.See also EMC-compliant electrical installation. Screened/armoured cablesThe screen must have low HF impedance, which isachieved by a braided screen of copper, aluminiumor iron. Screen reinforcement intended for mechani-cal protection, for example, is not suitable forEMC-correct installation.See also Use of EMC-correct cables. Extra protectionELCB relays, multiple protective earthing or earthingcan be used as extra protection, provided that localsafety regulations are complied with. In the case ofan earth fault, a DC content may develop in thefaulty current. Never use an RCD (ELCB relay), typeA, as it is not suitable for DC faulty currents. If ELCBrelays are used, local regulations must be compliedwith.If ELCB relays are used, they must be:- Suitable for protecting equipment with a DC con-tent in the faulty current (3-phase bridge rectifier)- Suitable for a pulse-shaped, brief discharge onpower-up- Suitable for a high leakage current. High voltage testA high voltage test can be performed by short-circuiting terminals U, V, W, L1, L2 and L3, andMG.04.A1.02 - VLT is a registered Danfoss trade mark32