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  1. whitbuzben

    Motor current ratings when using Variable Frequency Drive (VFD)

    Hi All, One more question on this. Could someone clarify for me the meaning of LRC(DOL) and LRC(SD) on the attached Brook Crompton motor datasheet? I think LRC(DOL) is Locked Rotor Current direct online. I am not sure of the other. An explanation would be appreciated. What is the difference...
  2. whitbuzben

    Motor current ratings when using Variable Frequency Drive (VFD)

    Great! It sounds like the consensus would be to use a soft starter. However, the chipper we are working with does have a very high inertia. Taking this into account it sounds like the VFD may still be an option despite the higher cost.
  3. whitbuzben

    Motor current ratings when using Variable Frequency Drive (VFD)

    Hi Guys, Thank you for the responses. djs is it definitely the 526 Amps that should be used for sizing the VFD. Surely it will not draw anywhere near this if the startup is controlled. Thanks ALL
  4. whitbuzben

    Motor current ratings when using Variable Frequency Drive (VFD)

    Dear Sirs, I am having a little bit of difficulty understanding the datasheet, which is attached, for a 315kW BROOK Crompton Motor. Specifically, I could use some help understanding the significance of the current values. Is the 526.2 Amps (labeled Amps Ia @ 400V) the locked rotor current...
  5. whitbuzben

    Reactive Power Production of AC XLPE Submarine Cable

    Dear Sirs, I have an XLPE submarine cable with the following characteristics: Cable Vn (kV) In(A) Rac(Ω/Km) L (mH/Km) C (μF/Km) 150 1088 0.0205 0.352 0.233 Using the parameters above can someone demonstrate how to calculate the reactive current in the cable in A/km and...
  6. whitbuzben

    Determining positive and zero sequence parameters ( R,L & C) for XLPE underground cable.

    Matlab script related to the above post is attached here. http://files.engineering.com/getfile.aspx?folder=7470d14f-8224-45dc-b4ce-9267c3323600&file=Electric_impedance_and_capacity_parameters_programm_for_radial_field.docx
  7. whitbuzben

    Determining positive and zero sequence parameters ( R,L & C) for XLPE underground cable.

    Dear All I am building a simulation model using the Simpowersytems toolbox within Matlab Simulink. I would like to model a 20km XLPE underground cable using the distributed parameters cable model contained within Simpowersystems. The cable is 3 phase and contains three conductors in a trefoil...
  8. whitbuzben

    Transformer with Multiple Primary Windings

    Hi guys Thank you for your responses. PRC I think you have managed to identify what I was looking for. Your example of a combined cycle thermal power plant where the gas turbine and steam turbine generators feed one transformer with two primaries having different voltages and different MVA...
  9. whitbuzben

    Transformer with Multiple Primary Windings

    Dear Sirs, I was wondering if it would be possible to have a transformer with multiple primary windings that would allow two different voltages (lets say 11kV and 6.6kV) to be connected on the primary side. There would then be a single output on the secondary side of 33kV. Presumably you...
  10. whitbuzben

    Power Factor at recieving end of wind farm transmission line.

    Thanks for the resposes guys. Collies99 your response confirms what I initially though. The PF at the receiving end will essentially depend on the characteristics of the load (though as highlighted by bacon4life the problem is somewhat more complex in the case of a wind farm). Out of interest...
  11. whitbuzben

    Power Factor at recieving end of wind farm transmission line.

    Dear Sirs I am trying to do a calculation relating to the connection of a 3.6 MW offshore wind-farm to shore via a 9km long subsea cable. The scenario is as follows and is taken from an example in a text book (page 236 Example 10.5 of the attached PDF): A three phase XLPE subsea cable...
  12. whitbuzben

    How to calculate the Rectified DC voltage from AC servomotor

    Hi Guys Firstly thank you for to ScottyUK for the link to the paper. cswilson i worked through the same calculation that you have done and came to the same conclusion. So i think you are correct. Although possibly someone could verify it for us. 98V(rms)/Krpm 98/1000 = 0.098V(rms)/rpm 1...
  13. whitbuzben

    How to calculate the Rectified DC voltage from AC servomotor

    Hi ScottyUk. I am not feeding the servo with DC. We have a motor/generator rig setup. Wereaby one of the motors is used as a generator that is driven by the other motor. It is the generator side that is being fed through a rectifier. I could give a full description of why we are doing this...
  14. whitbuzben

    Embedded Matlab Function Block

    I am working with a DSPACE unit and i need the code inrunning in Matlab so that i can trasfer it onto the DSPACE. I apologise ther is a small error in the initial post above. This might be clearer: function [AC_Contactor,DC_Contactor,AC_Precharge,DC_Precharge,X] =...
  15. whitbuzben

    Embedded Matlab Function Block

    Hi All I am using the embedded Matlab function block to write some code for a state machine. Within the block i have the following code: function [AC_Contactor,DC_Contactor,AC_Precharge,DC_Precharge,X] = V_ctrl_AC(B1,DC_Voltage_Ref,DC_Link_Voltage) AC_Contactor=0; DC_Contactor=0...
  16. whitbuzben

    How to calculate the Rectified DC voltage from AC servomotor

    Dear Sirs I am working with a Control Techniques Permanent Magnet AC Servo Motor. I am looking to feed the motor through a full bridge rectifier (Six Diodes) and would like to workout what the rectified DC voltage will be. On the data sheet the the Ke(voltage constant) is given as Ke = 98Volts...
  17. whitbuzben

    Calculating Torque Constant of small Permanent Magnet Generator

    Thanks for your responses guys. I think i will have to couple the generator to and induction machine and drive it at a known speed as Clyde 38 suggests. Just to clarify when you say "measure the voltage" this is obviously the open circuit voltage on the generator terminals with no load...
  18. whitbuzben

    Calculating Torque Constant of small Permanent Magnet Generator

    Dear Sirs I was wondering if anybody could provide me with some information on how to obtain the Torque Constant ,KT, of a small permanent magnet generator. The generator in question can be seen here http://dvetech.dk/?page=PMG&id=63. The part number is PMGO-0.2-200. I have also attached the...

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