We have twin EHV transmission lines approx 80km in length which are closely in parallel for their entire lengths, and are not transposed. Using Transmission Line Impedance calculators with the physical phase positions indicates that the negative and positive sequence impedances are not equal and...
I can’t find an Fortran function that rounds a real number to a given decimal place (such as ROUND(x,y) in VB). The only way I’ve found of doing it which works but is ugly is, for the case of wanting to round to the third decimal:
dummyVar = 123.456789
dummyVar = TRUNC(dummyVar * 1000.0) /...
The psse manual is only an excerpt from the model description. I am looking for a more full description of states and how to perform certain tests on the model.Eg. cable faults etc.
I am trying to track down the description of a HVDC PSSE model, known as CDCAB1. Unfortunately the psse manual is a bit lacking in the description. Does anybody know where I may be able to obtain this information from- it must be out there somewhere.
Thanks
From experience with the KBCH it is not always obvious the vector corrections needed for different transformer windings. I am not familiar with the Siemens relay range, but I know with the KBCH you can read the actual differential values the relay is seeing while on load. If this is possible...
We are looking at having a 50tonne reactor moved, and one of the big issues is the weight of the device. It would be a lot less expensive to ship the device with the tank empty of the insulating oil. What are the problems which could be encountered if this was done. The reactor oil needs...
I have been asked to looked at the termination requirements for two new 12MVA 33/11kV transformers. The specific question I have is to do with the earthing of the lead on the single core cables at the termination points. Is it better to only earth one end to prevent any circulating currents in...
The inrush current when energising a transformer has a large 2nd harmonic component, which is transient. i.e. if trying to analyse with a FFT the period in which oscillations occur needs to be sampled at a frequency of at least twice the highest required harmonic. The FFT on this data would...
Thanks for the reply, we do have all the HV feeder load data available for the past 10 years, I was just wondering what other data I should collect which should be of use in correlating the MD's to other effects (like weather). Your suggestion of light levels and rain may prove useful. Are there...
I am trying to study trends in load growth for our region over the past 10 years or so, to be able to predict future load growth. In forming a model, what data would be useful. i.e. I know there is a relationship between maximum demand and temperature, but what about other environmental effects...
I'm new to script programming in AutoCAD, the application I'm trying to write is to use EXCEL to automatically change the colour of lines in an existing AutoCAD drawings. I can write the Excel VB code fine, I just need to know if there is a simple way to change the colour of a line if you know...
I have experienced the same sort of problem when developing an Excel spreadsheet with a userform with a lot of input boxes. I tried unloading add-ins and all sorts but nothing seemed to work. Curiously I found that once I seemed to reach the memory limit, if I closed down excel, then loaded the...
In my previous post I did not mean to suggest that DC was more destructive than AC( although electricpete did make some interesting points on that subject) just that DC had a higher insulation breakdown voltage than AC. Maybe my reply could have been better phrased.
As for the statement that a...
Theoretically your KWH shouldn't change. The power factor is a measure of the ratio between real (kW) and reactive(kVAr). You can improve the power factor by increasing your kW load and keeping the kVAr component the same, or by reducing the kVAr and keeping the kW the same (as you say you will...
In our experience when dealing with power cables the only effective way to shield sensitive equipment from power cables is to increase the distance between them. Cable shields/ armours shield against electric fields but not magnetic.
This is a problem which we have found in the past, especially with large services. There have been a couple of ways around it. (i) as stated before use non-ferrous gland plates , i.e. aluminium or brass, but you will also have to be careful with your choice of gland materials. Aluminium is known...
I am having a bit of a problem with VB in Access, I can not find any methods to say whether a particular query already exits. There used to be an IfExists method which does not seem to be supported. Does anyone know how I could achieve this?
The cause may be internal or external, if your neighbours are having the same problem then there may be a neutral problem, or overloading of the supply cable/overhead line.
If it is only you that is effected (you say that it only happens in part of the house so this would seem likely) then check...
