I have used both ETAP and PowerFactory in a previous role (using CAPE now in my present role). ETAP seems more tailored/focussed on industrial power systems while PowerFactory seems to be used more for transmission power system modelling. As a result, the component models / libraries of each...
Hans-Henrik,
The notes under Table 1 of EN50522 mention “if there is no automatic disconnection of earth faults, the need to consider double earth faults depends on operational experience”. This might be relevant if your 10kV system is operated with isolated neutral or resonant earthing. The...
Are you plotting relative rotor angles? If so, your swing generator will be the reference for the relative angles of the other generators and appear to be at zero degrees during the simulation. If you have a second identical generator at the same bus as the swing generator that could explain why...
Kaspor,
I suggest that you are too quick to suggest that ETAP is “not adding fault currents correctly”. The detailed printout you provided clearly shows that the real and imaginary components add up at the bus and Kirchoff’s current law is satisfied. Yes, the different currents have different...
slugz,
If you expect a high ground grid resistance, bear in mind that this may reduce / restrict the ground fault current to less than the 14 kA value you mentioned. This won't solve all of your problems, but if your utility allows you to do this it may knock a few percent off your calculated...
The Transmission System Operator in Ireland, EirGrid, has carried out a number of studies looking at the challenges faced by power systems with high levels of wind/non-synchronous generation. The reports include a number of possible solutions which may be of interest. The reports are available...
Thanks prc,
I found what looks some useful data on the websites of those manufacturers. Once we get confirmation regarding what grade of CRGO steel will likely be used in the transformer we should be OK.
Thanks again,
IP
Hello,
I am looking for any suggestions members may have for good data sources or technical references for typical saturation characteristics of HV transformers. We are looking for this information in order to carry out a preliminary transformer inrush / transient overvoltage calculation.
In...
Hi PeZeKa,
The EN50522 standard doesn't make things easy, but it is possible to recreate the curves in Figure 4 and Figure B.2 using the equations shown in Annex A and Annex B (with more accuracy at some points than others...), and to use the same process to come up with alternative curves if...
HI RSChinn,
Short answer: Yes, I think you could in theory (and possibly in practice!) have touch potential issues at the metal stake or cyclone fence. In my own experience I have seen cases, both modelled and measured, where excessive touch potentials were present at third-party fences and...
timm33333,
If you are reasonably certain that you need a LPS anyway, then ScottyUK’s link is probably a good place to start, as this should indicate what Lightning Protection Level you require according to IEC 62305.
As there are several different levels of lightning protection allowed for in...
... or EN50522
For complex earthing systems you can use more advanced earthing software such as CDEGS, but there's not much point in doing that until you learn the basics, starting with reading the relevant standards and using the simplified equations from these standards. Start by reading the...
radug,
Thanks for sharing the values you've been able to replicate from EN50522. It does seem strange that two of the values are different. I occasionally need to use touch voltage limits calculated using faster earth fault clearance times (in cases where there is duplicate fast-acting/reliable...
radug,
Thanks again for the useful information. I wasn't aware that there were similar touch and step voltage criteria listed in standard EN50341 (for overhead lines) and in standard 50122 (for railways). As you say, it makes sense that similar criteria should be used for other types of high...
