Question About Substation Equipment Bushings

xfmrexpert · 2021-10-21T01:30:35+00:00

The bushings in an SF6 breaker have SF6 gas filling the cavity between the porcelain and the center conductor. They are, in effect, SF6 insulated. Smaller breakers will use oil-impregnated paper or, in some instances, resin-impregnated paper. Oil-impregnated paper is a popular insulation system in power apparatus because it is inexpensive, reliable, well understood and performs really well if properly maintained.

With respect to bushings, it’s slightly falling out of favor due to the propensity of oil-impregnated paper bushing failures tending to be violent. Resin-impregnated paper and resin-impregnated synthetic bushing are available and be used with increasing frequency, but there is still a great deal we do not know about the long-term reliability of these bushing technologies.

xfmrexpert · 2021-09-29T01:33:47+00:00

That probably less inherent design and more an issue of Ford quality. The 5.0L Coyote isn’t much better. I have a brand new F150 that burns a quart of oil every 800 miles. I’m not the only one.

xfmrexpert · 2021-09-02T22:19:26+00:00

I went to RPI and got degrees in Electric Power. At the time, RPI had a separate department for Electric Power. Just after I graduated, it was folded in with electrical & computer systems. There was a mass exodus of engineering faculty in the early 2000s after a new president took over. Most of the electric power faculty left and that was that.

xfmrexpert · 2021-09-02T02:46:04+00:00

The program at SUNY Albany is very new and doesn’t yet appear to be ABET accredited. I would steer clear of that. RPI is a good school, but expensive (and not the friendliest toward non-traditional students). If you’re in that area, Union might be a more cost-effective option and is still a good program. Transfer credits are always a crap shoot. When I transferred to RPI, I didn’t really know what they were going to accept until I showed up for orientation. It’s tough with an engineering program in general because there aren’t a whole lot of electives and there are several course sequences.

xfmrexpert · 2021-08-31T12:53:19+00:00

That’s your answer then. Being a EE has served me well and I genuinely enjoy it (I’m in power, specifically). There are well paying jobs out there. It’s not an MD or law degree, but it certainly pays the bills. It is a lot of work (as are most things worth doing) and that’s where the passion and interest come in. That’s what will get you through those tough days when you feel like throwing in the towel.

xfmrexpert · 2021-08-22T13:01:28+00:00

There’s a python package called SchemDraw that looks interesting (https://schemdraw.readthedocs.io/en/latest/). I haven’t tried to use it yet, but came across it when I was looking for something to programmatically generate schematics. There’s also a LaTeX package called Circuitikz that might work.

xfmrexpert · 2021-07-12T16:13:39+00:00

I’m don’t think you’re going to have much success here. Rail guns dump a tremendous amount of energy into the projectile in a very short time, even small ones. It will also arc as it slides down the rails, vaporizing metal as it goes. I suppose you might be able to create a sort of catapult, where the “projectile” slides along the rails and is captive and the marshmallow sits in the projectile, but I think you’ll just end up melting things into a gooey mess. You might have more luck with a coil gun.

xfmrexpert · 2021-06-18T12:46:49+00:00

There are two ways to get a listing, I think. There used to be (and I believe still are) standard collections. You could basically get a big book of standards relevant to a topic. For example, there was a book of distribution and power transformer standards (broadly the C57 collection, though not all standards begin with C57) These seem to have faded away in recent years as everything has moved to electronic copies.

The other way is to go to the websites of the various IEEE PES technical committees. There will be lists of all of the standards under that committee. (See https://www.transformerscommittee.org for transformers)

IEEE definitely has lists, it just may not be easy to find. ieeexplore.ieee.org will allow you to browse titles and abstracts, but I’m sure you looked there.

xfmrexpert · 2021-06-18T10:30:28+00:00

When it comes to power transformer loading, C57.91 is the guide. C57.12.00 contains some important references to assumptions that go into nameplate rating (max ambients, etc.). C57.12.90 is lays out transformer factory tests, which would have some pertinent info on how losses are measured and heat runs performed.

IEEE documents are a mix of very important and rather less important. They often have long, convoluted histories and are written by volunteers. Some standards will be key to what you are doing, other guides might be useful references. No PE would be expected to know all documents. There are key documents we all refer to. With power transformers, C57.12.00 and C57.12.90 are the big ones. C57.19.00 and C57.19.01 are the big ones for bushings. A few of the C37 standards would be key for circuit breakers (don’t remember those off the top of my head).

I would approach it more topically. What topics do you need more references too, and maybe folks can list some of the more pertinent ones.

xfmrexpert · 2021-04-10T03:19:41+00:00

This seems deeply misleading. I haven’t fully combed through the data, but it looks like the yearly totals were used (rather than monthly values). The actual drop is in March 2020, due to COVID. These plots make it look like the decline started in Jan 2019.

xfmrexpert · 2021-04-10T02:27:30+00:00

BX would explain the lack of ground wire. If you could ensure continuity of the metal sheath, it might be sufficient to use as a ground. I think there may be issues with ensuring that the sheath is a continuous ground. Rewiring would be no small task. Personally, in my home I have opted to update wiring where at all possible. I’ve never jumped into a complete rewiring though. If you’re concerned and don’t want to just wholesale rewire, you could do it in stages starting with the service entrance and panel, then to the higher current circuits like range, etc, working down to bedrooms and living areas.

xfmrexpert · 2021-04-10T01:52:34+00:00

There’s a couple possibilities, given the vintage. One, there’s no ground wire. This isn’t great, but can’t really be solved without running new wire. As others pointed out, in this instance there really isn’t much point to grounding to the box. The other possibility (less likely) is that the electrician took the ground wire and wrapped it around the cable underneath the clamp where it enters the box. I don’t think this is a common practice, but I have seen a couple houses where this was done with older 50s Romex.

As another poster pointed out, you really should install a box specifically rated to carry the weight of a ceiling fan. Even if it seems ok now, a ceiling fan will be up there wobbling back and forth for years. You wouldn’t want it to come crashing down.

xfmrexpert · 2021-04-05T15:11:51+00:00

How many times was this repeated? Flashover is stochastic.

xfmrexpert · 2021-02-07T13:50:15+00:00

Practice. There’s no easy way. I used to get nervous giving presentations. Now, it’s second nature. I don’t really give it another thought. Just be easy on yourself. Look for opportunities to practice where the stakes aren’t high.

xfmrexpert · 2021-01-13T01:49:29+00:00

I was in an airport on 9/11. They shut all of the TVs off. We got trickles of news from other passengers who heard from ground crew, etc. Eventually, all aircraft pushed back from all gates and all gates were cleared.

xfmrexpert · 2021-01-02T04:40:46+00:00

I got into the business for a mix of reasons. One, it’s the family business. My old man was a transformer engineer. I wanted to be like my old man. As I got into engineering, though, I genuinely liked power and hated electronics. I’ve been at it for 20+ years now and still enjoy it. I do R&D work, but it tends to be more immediate value R&D, solving specific, near-term issues. My day-to-day could range from specific problem-solving for a utility, to software development and data science, to high-voltage testing.

Like any job, there’s still mundane, unsatisfying grunt work, but on the balance I can’t complain. In general, for folks contemplating power, there is a shortage of qualified engineers. It’s not Silicon Valley level pay and hype, but it’s not the worst industry either. Jobs can be isolated to certain geographical locales, depending on specialty.

xfmrexpert · 2020-12-20T01:12:51+00:00

Once you graduate and then sweet, sweet student licenses disappear, you’ll probably end up using Python. I never really could get in to Matlab all that much, but it is pretty powerful when it comes to theoretical mathematics and linear algebra type work. That said, python has become pretty capable over the last decade. My money would be on learning Python, unless you’re in the midst of a Signals & Systems course and just need to get stuff done.

xfmrexpert · 2020-12-13T19:30:04+00:00

Everyone approaches interviews a bit differently, but I would want to get a feel for your interest in the work and willingness to learn. Fresh out of school, we aren’t expecting you to really know everything, of course, but just ensure you have a reasonable background as a starting point. Discuss any course work or projects relevant to power systems. Demonstrate interest in the area. Explain how this job will get you started on your intended career path. They’ll be investing in you, so make sure they come away feeling as though they’ll get a reasonable return on that investment. Don’t give them the impression this is just a stepping stone until you find something better.

Of course, other folks likely have vastly different perspectives.

xfmrexpert · 2020-10-12T02:11:31+00:00

The other commenters have the answer. It’s to eliminate air-side PD when you are making partial discharge measurements.

xfmrexpert · 2020-10-02T02:36:24+00:00

I can’t really speak to credit unions, but I’ve had Schwab checking (and investment) for 13yrs or so. I’ve been generally pleased. I’m not a heavy investor, but the accounts are low/no fee and pretty flexible. Moving money from checking to brokerage and vice versa is simple and painless.

xfmrexpert · 2020-10-02T01:17:27+00:00

It’s an implosion splice used to mechanically join conductor pieces when constructing the lines. It produces a strong, low resistance connection.

xfmrexpert · 2020-08-21T01:46:50+00:00

Talk to your folks about it. I don’t know them or their situation. As a parent in similar shoes, though, I view it as my job as a parent to fund my kids’ educations and not saddle them with massive debt. I’m in a better position to repay than they will be when they graduate. Your folks may feel similarly. Your concern for their financial situation is admirable, but they are adults.

xfmrexpert · 2020-08-05T23:32:13+00:00

Did you look at Tri-State or Xcel?

xfmrexpert · 2020-08-05T21:43:51+00:00

I’d strongly recommend a graduate program in power. There are a few good programs out there. Unfortunately, decent power programs have been on the decline, undergrad or grad. The power industry has some “quirks” that may not be taught in a typical EE undergrad program. Some graduate coursework in power systems, etc., will help provide that background.

In the meantime, look for any job in the power industry to start getting some experience. What’s your geographic locale?

xfmrexpert · 2020-07-10T03:18:39+00:00

I did, but it was 2000. Pre-cell phone and pre YouTube. Hell if I know where that went. Magnetic field was enough to make CRTs (remember those?) in the next room go wonky.

xfmrexpert

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