Hello all,
I am wondering if there are any advantages to using a 4-pole contactor when switching 3 single phase loads that operate phase to ground. I have a lighting circuit branch that is fed by a contactor. The lights are connected phase to ground on a 600V three phase system (e.g. lights...
Hey all,
Been a while since I have posted or been on this forum.
I was contacted by a contractor who has already installed grounding infrastructure for an islanded 600/347V system supplied by a 2MW generator. The island system has a section of 27.6kV overhead line to reach the far side of the...
Hi,
I have a question regarding line-ground currents and artificial neutrals.
I am modeling a solar power plant. The PV arrays' generated power is inverted and transformed onto a 27.6kV collector system which is then stepped up to 115kV to the grid. The main transformer is a 20MVA...
Hello,
I am performing an arc flash study of a PV plant with EasyPower and noticed something curious during analysis. If a DC bus is faulted, there is no contribution from the AC-side of the inverters that I have modeled. This wouldn't be true though as far as I can reason, since if the IGBTs...
Hello,
I have been requested to perform an harmonic analysis for the very first time (always exciting to learn new stuff [smile]). I have some training in this study area but to date have never applied these concepts. Specifically I am going to be performing an analysis at a water treatment...
Does anyone perform power system studies (short circuit studies specifically) in Canada? I do many studies in Canada (being that I live here) and I have come across something I probably should have asked earlier in my career: are UL 508A and NEC 2005 Standards and Rules regarding SCCR applied in...
Hi everyone,
I am doing a short circuit analysis on a manufacturing plant in the U.S. and have come across some bus duct runs in the plant that are under-rated for the calculated short circuit currents (22kA rms rated withstand, vs 27kA momentary short circuit, calculated at the end of the 100'...
Hi there,
I have some data for a power system model I am creating and I have come across a GEC low voltage breaker with a CTZ relay on it. Does anyone know of a source I can go to to find information on this relay, specifically TCCs? I have tried the internet and my typical manuals site, but to...
Hi everyone,
I have a question that is nagging me about short circuit ratings of LV fused disconnect switches. On many low voltage disconnect switches two short circuit ratings will be given. One will be given as 5 or 10kA with the statement "when installed fuses are Class H or Class K"; the...
Hello everyone,
I was wondering if anybody knows where I can find some old fuse TCCs for the now-nonexistent company CEFCO (Commercial Enclosed Fuse Company of New Jersey). I have some characteristic curves in EasyPower but I would like to find some old documentation on these fuses. The...
good morning,
I am performing a load flow study for the first time and I have been going through some old reports to make sure I am on the right track. I came across a report that identified the utility's short circuit availability (X/R, MVAsc) for use in the load flow study. Just so I am not...
Hello everyone,
I presently do power system studies in Canada and recently received a request from a client to quote a potential job in the United Kingdom, specifically an arc flash study. I was wondering if someone could point me in the direction to the calculation standards and typical...
Hi Guys,
I am working on a short circuit study with four generators (range in size from 5MW to 30MW). I have been provided the subtransient reactance, Xd'', however it turns out that all the values I have been given are unsaturated values. There isn't a way to relate unsaturated values to...
Good morning,
I am doing a short circuit study that includes a 50/60Hz frequency converter. I have never modeled one of these devices before and moreover, I have nearly 0 information on it besides the frequency and MVA rating. The modeling software used is ETAP.
I was thinking of treating it in...
Good morning,
I am sizing a fuse for a 1P 37.5kVA transformer that is tapped off of a 600V 3P 4w splitter. See below for one line:
________________________600V splitter 3p 4w
| |
| |
1P fuse 3P motors (200hp total)
|
|
1P 37.5kVA...
Good afternoon,
I regularly perform short circuit and arc flash studies and throughout the various plants that we analyze there is always one or two runs of cable that has no resistance information given in my known library of documents. I was wondering if there is an IEEE (or otherwise)...
Good afternoon all,
I am modeling a system that appears to have 50Hz equipment running on a 60Hz system.
I am particularly interested in knowing the affects of this difference in frequency on nameplate ratings on transformers. I can guess that the %Z would be 120% of the listed %Z due to the...
Good day,
I am new to the field of power engineering and this is my first post to eng-tips. If I have not provided enough information, then please let me know for future posts.
I have been given one line data and field information to enter into a model for a short circuit study. I came across...
