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  • Users: Jensdsds
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  1. Jensdsds

    VFD High Frequency grounding of stator vs. return path via. power cable tray + PE + bare Cu cable

    Hello, In a MV MW system with a VFD driving a motor, how do you handle grounding the High Frequency common mode currents? The rotor has shaft grounding which is grounded to the stator frame. Stator frame is grounded via the PE cable routed in the same cable tray as the power cables. The PE...
  2. Jensdsds

    Selection of voltage level for MV cables

    Hello, When selecting cable for high current power supplies 500A+, and a specific voltage rating of e.g. 3.3kV. The cable is between a converter and a large motor, so the system will have some switching dv/dT over voltages, but limited by a dv/dt filter. Do you then select a 3,3kV cable or...
  3. Jensdsds

    Heat transfer coefficient change as deltaT change?

    Hello, i'm a student in electrical engineering and i'm doing a project using COMSOL multiphysiscs tool to anticipate the temperature of a cable being subjected to a specific current. The test is done in real life and then simulated in COMSOL, to see if its possible to anticipate. Currently we...
  4. Jensdsds

    Changing the way COMSOL calculates the resistance of a conductor

    Hello, I'am doing a Joule heating study of a simple cable model. The cable has a terminal of 50A in one end, and a ground in the other end. A heat flux is added to the surface. My problem is: I am simulating a Stranded cable as a solid cable in comsol for time saving and mesh optimisation...
  5. Jensdsds

    COMSOL startup help

    Hello, this might be a long shot but here we go. I am looking for someone to assist me with some questions about the FEM software COMSOL. Specifically i am creating a single phase cable model which should be able to anticipate temperature rise at diffrent amps through the cable. I've build the...
  6. Jensdsds

    Center wire for EMC common mode return path

    Hello, I am looking for advice/knowledge on EMC common mode reduction in a VFD motor setup. The power cables are in the 300mm^2 sizing. My question is: Is a combination of a center wire inside a trefoil consisting of 3 single core cables phase ABC, and a well connected cable ladder forming a...
  7. Jensdsds

    Skin effect in Generator power cables at 120Hz

    Hello, I have some questions about skin effect. Information to know: Large Generator size MW. Power cables at 300mm^2 single core. When a large single core cable like the 300mm^2 cable goes from 50Hz operations to 120Hz, should i dimension it with new current reduction factors? I have...
  8. Jensdsds

    PE Cable placement in cable ladder

    Hello In a system with a large motor supplied by a converter. The cabling is three phase with a PE conductor. In the cable tray/ladder from the converter to the motor, Where should the PE conductor be placed? As close the phase cables as possible, in the same cable tray as the cables, or as...
  9. Jensdsds

    Well connected and teminated cable ladders?

    Hello, For at motor powered by power cables coming from a converter setup. The motor cables are being run in cable ladders which are all correctly connected to the earthing system. Everything is well correctly connected to the earthing system. My question is in regards to the common mode...
  10. Jensdsds

    Parrallel motor cables in trefoil, phase formation.

    Hello In a 4x cables pr. phase system, how would you create the most symmetrical formation create a minimum of current unbalance? With 4x cables pr phase it seems impossible to create 100% symmetry. My solution would be this setup: B A C B A C...

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