Recent content by andrewward

Hi All, Can someone please tell me how to soften black rubber? I have a window cleaning squeegee with a rubber blade. I didn't notice at the time of purchase that the rubber blade is really hard. It's not old, hardened rubber. But, just too hard to wipe across my car windows. Thanks Andrew

Hi All, I thought you might like to see where I got to on Probabilistic Planning. I had to write a report for my company and for a New Zealand industry body (www.eea.co.nz) on my attendance at the IEEE PES conference in Tampa. So I spent my energies on understanding the process of...

Thanks for the help Joe. I'll have a good look through your simulation. Best regards, Andrew

Hi All, this is all great stuff. Thanks for this. 1-2 days ago I found this engineering statistics web-book. Very good. http://www.itl.nist.gov/div898/handbook/index.htm However, I still haven't found an actual matlab/mathcad/Excel example that I can have a look through. I'm just not sure...

Hi All, I have been dropped into the deep end of reliability analysis and probabilistic planning for power systems (transmission and distribution) and need to get up to speed very quickly. I have read several IEEE papers on the topic and am now starting to understand monte carlo analysis and...

It is digsilent. Unfortunately there is no definition in their manuals. I am going to write to them for a techincal note. It is good software, but the manuals are not always helpful.

HI All, what is the difference between "Newton Raphson Classical" and "Newton Raphson Current Loop"? The NR Current Loop method seems to solve much more easily, especially for my power sytem that has voltage problems in a particular area. Actually the NR Classical won't converge, but the NR...

Sorry for such a long silence. I've had to give attention to a few other things at work at the moment. Thanks for all the responses. jstickley it IS an "all but the kitchen sink" problem. New generation is expected in a region of the grid and most of the power exported from this region...

The circuit is connected to a bus at each end with other circuits coming off each bus. But, the flows that I stated in the previous post come directly from the powerflow software and are the flows at each end of that circuit. The power flow solution did converge properly as well. I note that...

Hi everyone, I've been running power flow models and can't explain what I am observing and how to stop it. Can anyone help me understand what is going on? This is a real life situation. I have a transmission circuit of 100km with a power station at each end. At one end the voltage is set...

So does that mean a corner-grounded delta system is three single phase transformers connected so that one winding (e.g. LV winding) is delta connected? But, where each single phase unit has a permanent grounding jumper between the LV winding and the frame?

I know it sounds strange. But, digsilent allows me to do it! I wasn't trying to create a Y-D single phase transformer. But, I clicked those options by mistake and then that check box suddenly appeared. So I thought I'd ask to find out if anyone knows what it is for. Could it be an option...

Hi all, I am using digsilent and it provides a check box titled "LV-side, phase 2 internally grounded" when I create a single phase Y-D two winding transformer. What does it mean to have a delta winding that is "phase 2 internally grounded"? thanks heaps.

Thanks everyone for the help. Most appreciated. I now realise that I was after the definition that the Z% is the % terminal voltage required to obtain the rated current for a short-circuit secondary. We have been working on short-circuit currents.

Hi all, what does this phrase mean "a transformer with 5% impedance'? Is it just the p.u. impedance? Also, what are the formulae for calculating that percentage impedance? Thanks, Andrew