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Zero time delay for GF seems very short. Is the a requirement of the BESS manufacturer? Alan The engineer's first problem in any design situation is to discover what the problem really is. Unk.

Is anyone looking at either of these cloud apps? My firm currently uses Masterspec and we have been told it is being phased out this year and the replacement is a cloud based service called Specpoint. We got a demo account of Specpoint from our sales rep, but frankly the pricing we are being...

Thanks Dave. I found the article! Will read to see how well it answers my question. Alan The engineer's first problem in any design situation is to discover what the problem really is. Unk.

Thanks FacEngrPE. I did see the thread you referenced, but as someone in that thread also asked, I am looking for actual test data or even theoretical analysis of the effect ferrous raceways on inductance of a single conductor. Alan The engineer's first problem in any design situation is to...

It is well known that an un-bonded ferrous metal sleeve or conduit surrounding a single conductor adds substantially to the inductance of the conductor. Does anyone know of any actual measurements of this effect, and the effect of bonding the sleeve to the conductor? IEEE 142 (Green Book)...

Thanks all. It was suggested that saturation may not be a significant concern in a current limiting reactor because the protective device (fuse or circuit breaker) would operate before saturation can occur. I said that doesn't seem right to me, but I would like to have something to back that up...

Thanks Gr8blu. I understand the B-H relationship and saturation in general. My question is: is there a time factor between B and H? Say you apply a certain field H as a step function in time sufficient to cause saturation. Does the iron actually saturate instantaneously or does it take a...

When an iron core reactor or transformer is driven into saturation, is there a finite amount of time required for saturation to occur? Textbooks always discuss in terms of B-H curve, but time is not generally a parameter. Alan The engineer's first problem in any design situation is to discover...

Simplistically you have to model the generator as a voltage source, shunted by the generator internal impedance in series with the line impedance and fault impedance. Generators tend to be fairly reactive (high X/R) and lines more resistive. The governor will attempt to maintain constant...

NFPA 70E (2021) Table 130.5(C) provides guidance on the types of tasks and conditions that may or may not require PPE. Alan The engineer's first problem in any design situation is to discover what the problem really is. Unk.

Not to be argumentative, but I live in the eastern interconnection (SPP area) and we have had rolling blackouts two days in a row. It was -14F this morning when we went dark and the house got cold very quickly. Unlike some of the ranting crazies on Facebook, I gladly accept an hour of cold...

Dvhez, Many drawings of actual facilities are confidential for one reason or another. Google is probably your best friend for this search. Here are a couple of sites with some examples that I found with a quick search...

Hello! I've been away from eng-tips for a while, but thought this would be a good question for this group. The 2017 NEC, paragraph 240.67 requires, starting in year 2020, that low-voltage fuse protection 1200A and larger have a means to reduce potential arc energy, similar to the present...

At least one manufacturer in the U.S. produces windows that can be angled and can rotate to allow better view of the interior. Might help for restricted space as you mention. Alan The engineer's first problem in any design situation is to discover what the problem really is. Unk.

I have nothing but good experiences with SEL. The manuals are extensive and there is a learning curve to be sure. Their application engineers are knowledgeable and responsive. Field support is great also. Nearly everyone I know who works there likes the company and a couple have tried to recruit...

mfische, Please take tomatge's advice to heart. I think it would be fine if you would work with an experienced engineer on this, but relay settings are not something to undertake on your own. You may understand the principles involved, but there are many nuances and "gotchas" that present...

Way back in 2009, I posted thread238-234338 here about failure of surge arresters on a 4.8 kV ungrounded delta system owned by my client. I received some excellent feedback at the time and thought I would post an update. The arreters were replaced in 2009 with new IEEE C62.11 station class...

In the U.S., railroads commonly use pole-top transformers as step-up to feed distribution along tracks in remote areas. Some of these circuits are fairly long (up to 30 or 40 miles) and I'm sure the transformer losses are small compared to other losses. Alan “The engineer's first problem in any...

SKM doesn't allow you to manually edit the contents of the labels. They are printed based only on values calculated by the software. I was just hoping to find an SKM user who might have found a work-around. It allows you to build a table for "custom labels", but it still calculates the incident...

Thanks guys. I agree with the consensus about using the worst case. My original question was how to make the SKM software create these worst case labels somewhat automatically. I have systems with a lot of these transformers and would prefer not to do the calculations manually for every one...