High Resistance Grounding (HRG) systems limit the fault current to such a low value that the breaker does
not have to trip and the loads continue to function without interruption.
Best presentation I found on net is on site
www.i-gard.com
you can Download everything you need to have arguments...
As Slava said it is only for a protection or to be precise by grounding CT you get the currents maximized at 1.7 of nominal. I can search over on my papers for detailed explanation of this but I believe that this satisfies as an answer to your question
My sister works in Siemens in sales and even she has the problem handling the informations she needs. She works in Europe and that should say about the organization of company. Siemens is Huge, a giant and I doubt that ABB can buy it, it can only merge. In principle when I look for specific data...
I guess that all major producers have it but if you want one name its Siemens and you have it all over the world, so you don't have to search too much for it. (Also check GE, ABB, Schneider...)
One addition this means that you need to have symmetrical 3 phase system at beginning so you can have neutral point (star) on it grounded, and I suppose you have symmetrical system.
If you need a neutral you need to create one. It is simple system. You ground a starting neutral point for entire system and than run neutral around where you need it. You should not ground neutral on some other place and you should not connect grounding to neutral at any other place. This is...
I would disagree with short circuit test on a second hand transformer for more than 0.35s unless you have a chance to get it back to the supplier if it fails on the test. I remember one story from my lectures. My professor was hired to test some transformers built for the 600MW power station...
Well for start before you can ask your self what is the maximum value of the grounding resistance you must ask why do you put it at all? Most of the people meet grounding as another boring requirement from the law, but it has a great value. By definition grounding is put to make shortest path...
Well try to buy used transformer and sell it after you don't need it as used transformer, with copper prices rising you would be able to earn some money on it in stead of loosing it. Lease would be very expensive because if If anyone had a transformer on side he would like to pay back that...
First you should ask for their maintenance data to look what problems they had. In general you should look how they react at over current/over voltage, and that transformers should withstand 120 % load for few hours, 160 load for 15 minutes. You use thermal vision for determining are the...
There is a phase shift between transformator sides that is equal to a n*30 degrees where n is whole number. n is called hour number and is usually mentioned on the nameplate. This is definition of the hour number for transformers, It goes in all European standards, so I believe it sounds the...
you are calculating 3+3+4 single phase load by taking 4 for all. It goes for cable calculation but not for consumption.
Your consumption is 10*500W/120V + (5*500W)/(1.73*208V)
This means one phase will have load of 24 A while rest 2 will have current of 20A. For a equipment choosing you...
http://www.helukabel.de/index.php?lang=en
http://62.180.125.140/cms/en/webkatalog/katalogeinstieg_aufzugs_und_foerdermittelleitungen_ausgleichsleitungen_oelflex_lift/1/index.html
they have their cable pictures so you can have an idea how does the cable look like, and a pretty good explanation...
1/3 of mains size can be allowed for grounding. Considering your reference point should be ground, than you should create neutral and grounding from grounding system and never to connect them on some another spot in a circle. If your kWh meter requires neutral, you should look if his prime is...
http://www.smg.uni-karlsruhe.de/~stefan/Pubs/2005-ISEMA/P08_Hauck.pdf
Describes methods for doing that ground resistivity measurement. As I can see those are pretty advanced stuffs for most of us mortals to lay hands on such gear :)
Found the:
http://gsa.confex.com/gsa/2002NE/finalprogram/abstract_30723.htm
They say in that abstract:
"An electrical resistivity survey conducted by the Wenner method at closely spaced electrode spacings was used to determine the vertical extent and resistivity of the frozen ground. This...
Scotty I am going on a vacation in few days and I will see that I speak with my godchild father that is doing electrical maintenance for over 30 years on electrical equipment for 2 million people city and had all kinds of problems with all types of gears. I will see with him how did they...
Software for drafting --> AutoCAD
For the draftings like TurbineGen said check in your company for older draftings. That is from what I started, now they are working with my drafting as a roll model for newbies. The way how technical drafting should look like are usually defined in national...
