Hi all,
I first want to apologize because I can't imagine that this question hasn't been asked...but nothing turns up in my search for X/R in the key-word...so here goes:
I find that in estimating X/R ratios, I always end up using a graph of typical X/R versus machine kVA from a GE tech paper...
Hey all,
A friend of a friend's house burned down last week. The cause given to them (from who?) is that a coiled extension cord was the root cause.
Now i^2 r being what it is, I can understand that a cord passing current will heat up - even if not to "overload". And although I'm a sparky...
Hey All,
We're having some system problems and one of my fellow engineers mentioned the possibility of commutation notching/recovery exciting a resonance in a parallel transformer. I haven't heard of this specific problem before (but I'm rather new). I was wondering if any of you have.
Has...
Hi all,
Figured the VSD guys would have some good answers for me...
I am using a component level time domain analysis suite as a simulation package to verify some of my customer's submittals (done in Matlab). I'm only after the correct top level behavior, not anything too specific. My main...
Hey all,
I understand all designs are a little different...I'm just looking for generic guidance....thanks a lot!!
I have a situation where I need to feed many (what of I'm guessing are)switch mode power supplies along with HMI displays, video cameras, various communication devices, etc. from...
This may sound like a stupid question, but I have an issue that's been driving me crazy...
While I'm working in "Spreadsheet A", I have available to me the standard color palette. I use a lot of color formatting in my database to segregate different types of items.
If I open a second...
Does anyone have any advice on choosing circuit breakers to operate at DC? Looking at a 725 VDC 2 wire, ungrounded system, it seems like I'm going to need to series at least 3 poles and break the return path too (another 3 poles)...
It sure would be nice to be able to do this with only 1 CB...
Hi all,
I'm using the circuit simulation package Simplorer to try to determine dynamic behavior of a circuit due to an arc. The arc will be modeled on the output of a rectifier bridge. I was wondering if anyone had a relatively simple approach to modeling this DC arc. I have researched the...
Hi All
Does anyone think it would be worth my time to try to include harmonic filter contributions to some fault current estimations that I've been making? So far, I've ignored them assuming the time constant of the filter is small compared to 1/2 cycle calcuations & the contribution would be...
Hi all,
I was wondering if anyone could tell off the top of their head why IEC 60909's Method B uses a 15% multiplier when estimating the symmetrical fault current??
I'm under the impression that the X/R ratio used by IEC is from a combined R & X network reduction. Is the 15% adjusted...
