Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Recent content by 3winding

  1. 3winding

    IEEE 835 Load Factor Calculation

    racobb, That is the quandry, if I use the 75% load factor, my 100% ampacity is much higher, thus I need to be satisfied I am not overloading the cable. The load is a wind farm with a projected capacity factor of 40%, using the 24 hour time frame and collecting real time data from existing...
  2. 3winding

    IEEE 835 Load Factor Calculation

    Racobb, I don't think this is the intent of load factor when applied to the IEEE tables. For instance, if I load a cable to 100% for a month, and then do not load it for the other 11 months, and calculate a yearly load factor, it would come out to be 8.333%. If I applied a low load factor to...
  3. 3winding

    IEEE 835 Load Factor Calculation

    Thanks that gets me heading in the right direction. The next question is will the time window used affect the calculation and ultimately cable heating.? Hourly, daily, weekly, monthly, annually? The cable obviously takes a period of time to heat, Neher and McGrath must have taken into account...
  4. 3winding

    IEEE 835 Load Factor Calculation

    7anoter4, Thanks for the link to the Neher and McGrath paper. I had a read but it still does not define how to specifically calculate load factor. In the IEEE table examples it gives a specific load factor but does not state how it was arrived at. I have a load that is very cyclic in nature...
  5. 3winding

    Load Factor and Cable Loading

    How is load factor calculated in the IEEE tables?
  6. 3winding

    IEEE 835 Load Factor Calculation

    I am using IEEE 835 to determine cable loading and I can not determine how the standard defines load factor or how to calculate.
  7. 3winding

    Voltage Sag Due To Transformer Starting

    dpc, I am aware of the 12 times for 0.1 sec inrush factor. I'm not sure how to apply that to voltage drop. I thought maybe there was some rule of thumb such as - if the utility had a 500MVA SC capacity and I was energizing a 50MVA xfmr, I would see a worst case voltage drop of some percent...
  8. 3winding

    Voltage Sag Due To Transformer Starting

    Does anyone know how to estimate the voltage sag on system voltage upon energizing a transformer, using transformer and system impedance? I am trying to determine a ball park number before going to some type of transient analysis evaluation.
  9. 3winding

    Induction Generator Info needed

    Also, you will need a protection relay. A Basler BE3-GPR or GPS-100 are economical choices for smaller units. There is a company called Thomson Technology that provides turnkey controllers, not sure if the do turbines though. You may also want to add power factor correction capacitors, which...
  10. 3winding

    Induction Generator Info needed

    What do you mean by starter? I assume you are starting the generator with the turbine and running it to sync speed? You just need a speed switch to give a close command to a breaker and then a governor to control it. I have used Woodward 2301D on many induction generators and they give great...
  11. 3winding

    SLG Fault Contribution From 3 Winding Transformer

    Scenario. Mulitiple generators connected to the grid through a Wye/Wye transformer with a Delta Tertiary (buried). For a SLG fault on the HV side of the transformer, will the grid contribute SLG current through the transformer? The SKM model I am running shows a higher SLG current on the HV...
  12. 3winding

    Effect of voltage on fixed capacitor

    Okay, so if the voltage rises to 37kV what is the output of the caps?
  13. 3winding

    Effect of voltage on fixed capacitor

    What effect does changing the voltage have on a fixed capacitor? Lets say a substation has a 10MVAR capacitor rated at 34.5kV. If the system voltage goes up or down, how does the MVAR output change?
  14. 3winding

    Zero Sequence Voltage 3Vo

    Is Zero Sequence Voltage detectable through a Delta transformer winding? It appears that the Delta would block it the same as zero sequence current? Is there any good references on applying zero sequence voltage protection settings?

Part and Inventory Search