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...
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...
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...
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...
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...
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.
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...
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...
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...
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?
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?
rraghunath,
Could you elaborate on the 3rd harmonic content required to keep the voltages sinusoidal?
The overvoltages seem to be occuring randomly.
alehman, the waveforms have a distinctive notch near at about 70 - 80 degrees and again 180 deg later.
To add more detail. It is a DG site with multiple generators connected to a 480V GrdY/ 13.8kV Grd/Y step up xfmr which is then connected to a 13.8kV Delta/ 69kV Wye step up. When the system is not generating the 480V system consumes power. We are seeing distorted voltage waveforms whether the...
I am trying to determine why it is not advisable to supply a grounded wye transformer from an ungrounded source? IEEE c57.105-1978 and other literature states this configuration is not advisable.
Does anyone know of references that will help determine apparent soil resistivity as seen by a ground rod encased in bentonite?
IEEE Std 80-2000 states that bentonite has a resistivity of 2.5 ohm*meters, but I would speculate this would not be the apparent resistivity as seen by the electrode?
