|
wolrah posted:For the electricity pros, here's a shower thought that's been bouncing around my head this morning: If you were in charge of building a new grid from the ground up where for whatever reason compatibility with existing devices wasn't an issue in any way, what would you do differently as far as the power that gets delivered to end users? There's not really a 'best' set of voltage / frequency, any choice will be slightly better either for the utility or end users (or equipment manufacturers) but it'll work unless you go to extremes. In general, higher voltage means lower losses but it kills you more easily and requires more insulation. If sockets in your home were at 10 kV you'd have a lot of dead DIY'ers and a phone charger would cost thousands, but almost no electrical distribution loss. Higher frequency means smaller motors/transformers but more losses. In an airplane 400 Hz makes sense because distances are short and the weight savings are worth it. 50 or 60 Hz is a wash but lower frequency would be more expensive to build motors / transformers for. Getting DC installed in buildings is really not worth it. Even datacenters use AC and have the final DC transformation done in the server equipment and that's about the best use case for DC distribution. Higher DC voltages are quite a bit more dangerous as well, 230 VAC stings a bit but 220 VDC really loving hurts (a control voltage used by engineers lusting for contractor death).
|
#
?
Jun 10, 2015 13:41
|
|
|
|
| # ? May 12, 2024 19:55 |
|
|
Pvt Dancer posted:In an airplane 400 Hz makes sense because distances are short and the weight savings are worth it. 50 or 60 Hz is a wash but lower frequency would be more expensive to build motors / transformers for. 400Hz is also an industry standard for sensitive electronics. Especially Military and Aerospace. Pretty much everything Radar/Sonar and all the associated signals analysis is all built on 400Hz systems for better performance.
|
|
#
?
Jun 11, 2015 00:29
|
|
|
some texas redneck posted:My question is, what happens to everything downstream when some idiot does that? Is there sufficient protection to prevent something like that from affecting utility customers beyond a brownout/blackout? Or do they get a Fortunately this is a very rural location, the calls they were getting were irrigation pivot pumps not working, cell tower called in with voltage alarm, etc. Depending on lots of variables, you may or may not have noticed it, especially the lower your load. As far as "surge protection" goes, I'm no expert on it, but I assume you'd actually need something that would disconnect you from utility power automatically, like a UPS. A word on surge protection in general, from what I've noticed there's not necessarily any rhyme or reason where lightning ends up at, and there's not much you can do about a direct or nearby strike. I've had to deal with quite a few customers who blame us, but we have a LOT of lightning arresters online, I don't know what else we can do about it. I think the best thing you can do to protect yourself is to verify the ground connection at your service. An electrician or maybe your utility can check your ground rod with an earth resistance tester. And often, it doesn't even come in on the power line, lightning can get on a phone line and run for miles. Here's one I found that was pretty... obvious.  
angryrobots fucked around with this message at 05:39 on Jun 13, 2015 |
|
#
?
Jun 11, 2015 01:31
|
|
lesson about how important surge protection is?
|
angryrobots posted:A word on surge protection in general, from what I've noticed there's not necessarily any rhyme or reason where lightning ends up at, and there's not much you can do about a direct or nearby strike. I've had to deal with quite a few customers who blame us, but we have a LOT of lightning arresters online, I don't know what else we can do about it. I think the best thing you can do to protect yourself is to verify the ground connection at your service. An electrician or maybe your utility can check your ground with a "Megger" which is an earth resistance tester. Resistance to Ground is with a Megger, the actual ground should just be with a regular Ohmmeter. If you need a Megger to read a ground connection then your ground connection already has serious issues.
|
|
#
?
Jun 11, 2015 17:54
|
|
|
Megger is a brand name that sells a variety of test equipment; ground resistance testing is not my area of expertise, but I know a few who do it sometimes, and they all refer to their equipment as a "megger". The test equipment I've seen used at service locations is the clamp-on type.
|
|
#
?
Jun 11, 2015 18:06
|
|
|
Those dudes must be living in their own tiny little world then, because I've never heard anyone use "megger" as a lowercase noun/verb to refer to anything other than insulation resistance test sets/testing. It's like Kleenex and facial tissues.
|
|
#
?
Jun 11, 2015 19:16
|
|
|
Noctone posted:Those dudes must be living in their own tiny little world then, because I've never heard anyone use "megger" as a lowercase noun/verb to refer to anything other than insulation resistance test sets/testing. It's like Kleenex and facial tissues. Yeah. Even when we had a Megger(r) mega-ohmmeter and a Megger(r) hi-pot tester, only the mega-ohmmeter was the megger, the other one was a hi-pot. In the same way, the "fluke" was the fluke 77 multimeter, even though our ground rod tester was made by fluke.
|
|
#
?
Jun 13, 2015 04:34
|
|
|
I work on power lines. The god drat thing that the guy checks ground rods with, says "megger" on it and that's what they call it. I went to a troubleshooting course with the TVA one time, and the instructor from two states over, also called it a "megger". What can I say, line work is a large fishbowl and slang terms abound. But I edited it out of my post anyway, so that's that.
|
|
#
?
Jun 13, 2015 05:52
|
|
|
Is it industrial if it's mostly commercial and residential? I called in a report of flickering lights last night. They weren't flickering often, but when they did, they'd go off for about 1/4 second, sometimes with a very loud bang and a bright flash from outside. Enough to piss off any electronics not on a UPS. And by flicker I mean they went completely off, then came back to full brightness immediately, so it's not like an auto recloser was involved. Our residential distribution is underground in the neighborhoods, but feeders into the neighborhoods are above ground (a mix of 7200 and 13200 IIRC). I looked up the outage map (Oncor, if you're wondering), and saw that 93 customers in my immediate area had already filed complaints about power issues. Went ahead and added my address anyway. Went out for a drive, saw an Oncor truck driving up and down the major road nearby, pointing a spotlight at every pole. I noticed one pole was (barely) arcing at a disconnect. Anyway, lots of kabooms, lots of flickering lights. They eventually call my stepdad's cellphone (acct is in his name, though I entered my phone # for the call back, but whatever), and.... there's someone knowledgeable on the phone. Not a call center script monkey. He tells me they had a short somewhere underground, but the only way to actually isolate it without taking down the neighborhood was to just disconnect poo poo and replace fuses until poo poo stopped blowing fuses. The person I spoke to actually told me what intersection the fault was at (about a block from me), mentioned it was an underground vault, and told me it was likely caused by all of the recent rain. So up to my questions How hard is it to isolate a fault on a live medium to high voltage circuit while live, particularly underground? Just start isolating circuits until fuses stop making earth shattering kabooms? How common is it for a poco to actually call someone back at 4am to respond to a complaint of flickering lights? That really blew my mind, especially the fact that they had someone extremely knowledgeable call me. As quiet as the background was, there's no way he was in the field. Kind of sucked being woken back up, but I was really impressed that they actually called, AND took the time to explain what was going on. randomidiot fucked around with this message at 12:18 on Jun 22, 2015 |
|
#
?
Jun 22, 2015 12:16
|
|
|
some texas redneck posted:
Sometimes they don't work, or weren't installed. So you open up equipment and look for something burnt up. Find nothing, pull off a termination halfway and throw a new fuse in to find it the hard way. If it holds, keep picking up a section at a time until it blows, and you've found it. If it blows, you know it's in the first half. Split in half again and re-fuse until you isolate the bad section of wire, or whatever is bad. They make test equipment that potentially can give you exact distance to the fault, but a service man called out won't have that (big and heavy equipment) and his goal is to get the lights back on. So... Every time they threw that fuse in, looking for the fault, the recloser that feeds your circuit saw the fault and operated one time on a fast curve, blinking your lights. If you ever have your lights blink 3 or 4 times in a row, then go out, more than likely there is a fault on your circuit and a recloser operated through all its curves before locking out. quote:And by flicker I mean they went completely off, then came back to full brightness immediately, so it's not like an auto recloser was involved quote:How common is it for a poco to actually call someone back at 4am to respond to a complaint of flickering lights? That really blew my mind, especially the fact that they had someone extremely knowledgeable call me. As quiet as the background was, there's no way he was in the field. Kind of sucked being woken back up, but I was really impressed that they actually called, AND took the time to explain what was going on. angryrobots fucked around with this message at 22:22 on Jun 24, 2015 |
|
#
?
Jun 24, 2015 22:19
|
|
|
angryrobots posted:That really depends, completely situational. What sounds like was happening here, is that the fuse initially blew on the underground, and for whatever reason, they couldn't pinpoint it in the field. We use "fault locators" which come in various styles and for different applications, but the idea is that you have them along a circuit, and if it "sees" a fault, it will flag via a flashing LED light or some other means. Really great fit underground, can put you right on the bad span of wire or equipment. Ah okay, when I've seen the lights go on/off 3-4 times, they usually go off for a full second, come back on (usually flickering), go off, etc until it hits 3-4 tries. I figured the flicker I saw the other night was just the brief short before the fuse popped again. Makes sense though, I know during our last winter storm, a tree got tangled up in the lines feeding into the next neighborhood (I could see/hear it from my back yard), and my lights were flickering pretty badly, then they went out for a split second along with a loud bang outside, and came back on at full brightness almost instantly (next neighborhood lost power for several days though). I always figured reclosers waited a second or two before reclosing, I didn't realize they had different curves. My only knowledge with fault locating was when I worked for a telco/ISP - most of their central offices had equipment that could pinpoint a break, right down to how many wire feet from the CO it was. It also detected plenty of other stuff, including one that made the hair on the back of my neck stand up once ("DANGER: 120VAC DETECTED ON CIRCUIT" or something similarly worded), DSL signal quality, etc. When I reported the flickering lights, I pulled up their outage website and saw that they had one reported nearby affecting nearly 100 customers, and it was nowhere near the estimated time of restoration - I figured my report would just get lumped in with the others, assuming I was on the same circuit. Unrelated, but several years ago I was living in an apartment complex. During a pretty good storm, I saw a bright flash, associated bang, and everything went out for a few seconds. Happened several times. I went outside after the storm and saw a pole leaning over far enough that the lines were about 10 ft off of the ground, and every time the wind kicked up, they'd bang into each other. What would you call a "reasonable repair time" to be on that? (reason I ask: it took over a week for them to come out and put insulators on the wires, and about 2 months to fix the pole... also Oncor, and it took out the entire apartment complex [300+ units] every time it went out - and it went out as many as 30 times a day depending how windy it was until they brought out the insulators) randomidiot fucked around with this message at 06:53 on Jun 25, 2015 |
|
#
?
Jun 25, 2015 06:50
|
|
|
I work for a relatively small cooperative, and that would have been repaired immediately.
|
|
#
?
Jun 25, 2015 12:53
|
|
|
Last time I was in Austin, a car accident took out a pole. Didn't break the wires, but had it leaning at a nasty angle, almost out of the ground. Power company shut off the power, replaced the pole, and had the power back on, all in the span of about 2 or 3 hours. I thought that was drat impressive. At the apartment I was at in Dallas (the one I described above), nobody would ever give us an answer as to why it couldn't get fixed - the pole that was leaning was actually in an alley that ran behind the apartment property, so the leaning tower of power was actually on city property (the next pole was in the apartment parking lot, and the lines transitioned underground from that pole to the various pad-mount transformers around the property). The entire portion of the apartment complex that faced that pole would call 911 every time it went BANG, thinking a line had gone down; Dallas FD would show up, call Oncor, Oncor would shrug and say "we're working on it". Calling Oncor about damaged electronics was met with a "file a claim with your renters insurance" (my microwave, both cable boxes, and PC power supply all let the magic smoke out; my TV has been flaky ever since). I live in a suburb of Dallas now, but it's still Oncor territory (as is a lot of Texas). I don't know if the faster response is because I'm in a suburb, or if Dallas just throws up that much red tape over fixing poo poo. It likely doesn't help that power in DFW is largely deregulated - meaning you can choose who "services" your power. It's still ultimately Oncor generating and distributing it, you just choose who bills you. Oncor doesn't have to answer to customers. I lived in a college town about an hour away a few years ago - they have their own power co-op run by the city, and rates were adjusted quarterly (I think) with the price of natural gas. Take it or leave it, we're your only choice. The rates were downright reasonable compared to the companies that are billing in deregulated markets. randomidiot fucked around with this message at 08:50 on Jun 26, 2015 |
|
#
?
Jun 26, 2015 08:46
|
|
|
Repair time really depends on the company. The one I work for, if customers are out of power it gets fixed as soon as possible. However the power company that supplies my home, if a pole or two goes down, you are out for at least a day.
|
|
#
?
Jun 26, 2015 15:02
|
|
|
For whatever reason, my power very rarely goes out, even though the entire subdivision around me may be blacked out for days after a nasty storm.  There's a police station just down the street that also seems to only lose power when I do, so I'm guessing we just lucked out and wound up on the same circuit? I've always heard stuff like hospitals, police stations, fire departments, etc tend to be high priority for power companies anyway. Half of my street pretty much never loses power, while I can drive around the neighborhood after a storm and see only candles/flashlights. All of our power in the immediate area is underground except for medium voltage distribution lines coming into the neighborhoods. In 15 years of being in this house, I can only think of one time when it was out for more than a few hours - straightline winds snapped a few poles on a main road outside the neighborhood (... one of which then fell over on a house and burned it down, thankfully it was vacant/for sale, and equally good, it was still insured by the owners). There were several hundred thousand customers without power in the metro area at one point, we didn't have power for 4 or 5 days. Cleaning out a fridge after that... 
|
|
#
?
Jun 29, 2015 08:01
|
|
|
wolrah posted:For the electricity pros, here's a shower thought that's been bouncing around my head this morning: If you were in charge of building a new grid from the ground up where for whatever reason compatibility with existing devices wasn't an issue in any way, what would you do differently as far as the power that gets delivered to end users? I'd go with 400Hz 3 phase for everything. Voltage? Ehh, we are about in the right spot, much lower and your copper costs skyrocket, much higher and insulation gets difficult especially at connectors. There's no real reason (at least as far as I can tell) for low frequency AC anymore. The whole reason it was good was because it allowed big, clunky, slow spinning generator equipment with not very many poles, you could synch clocks and movie projectors off it, and it allows for lovely old mercury and selenium/germanium/silicon semiconductor rectifiers to still be reasonably efficient. We have buck/boost regulators and other semiconductors now that go up into the MHz range and the rest is no longer relevant really. The best part of going up in frequency is that it reduces copper and iron costs for building transformers amazingly, for example the transformer in your modern active power factor correcting 500W computer SMPS is the size of an aerosol can cap at most and weighs like 4 or 5 ounces and is probably in the 50kHz to 1MHz (approx) range depending on how old it is, while the transformer out of my Northstar Horizon is a 250W linear unit that has a 40+lb transformer in it, operating off 60Hz line power. And that 500W unit is probably ~90% efficient while the 250W linear is maybe 75% if they were lucky.
|
|
#
?
Jun 30, 2015 03:01
|
|
|
kastein posted:I'd go with 400Hz 3 phase for everything. Voltage? Ehh, we are about in the right spot, much lower and your copper costs skyrocket, much higher and insulation gets difficult especially at connectors. I dont know about other companies, but we dont really use copper anymore. Everything is aluminum now. No more copper bus, I cry a little every time we throw it out.
|
|
#
?
Jun 30, 2015 10:19
|
|
|
We use it a fair bit for jumpers, but in some cases I think it's just a case of "that's the way we've always done it".
|
|
#
?
Jun 30, 2015 13:57
|
|
|
TheFargate posted:I dont know about other companies, but we dont really use copper anymore. Everything is aluminum now. No more copper bus, I cry a little every time we throw it out. True, I'm used to low current stuff where aluminum usually isn't allowed. I haven't seen any plant wiring over ~1ga in copper... ever.
|
|
#
?
Jun 30, 2015 15:32
|
|
|
TheFargate posted:I dont know about other companies, but we dont really use copper anymore. Everything is aluminum now. No more copper bus, I cry a little every time we throw it out. We use tin plated copper bus bars. Tin whiskers have a very strange texture.
|
|
#
?
Jun 30, 2015 15:38
|
|
|
helno posted:We use tin plated copper bus bars. We occasionally use tin coated stranded copper but 99% over everything now is aluminum. For any hanging/suspended stuff it usually has a steel core. But as far as bus goes, all aluminum. Everything from 4kv to 500kv
|
|
#
?
Jun 30, 2015 16:04
|
|
|
kastein posted:
While a higher frequency allows the use of smaller transformers it reduces the effectiveness of transmission lines. The drawbacks include: 1. A higher resistance of the conductors due to the skin effect. 2. The impedance of transmission line capacitance is proportional to the inverse of frequency. Going from 60-400Hz would cause reactive power consumption to increase 6.7 times. Since P=I^2 R, this means the resistive losses due to the line charging current increase 44.9times on top of the increase in resistance due to (1). 3. The amount of power that can be transmitted across a transmission line is proportional to the inverse of the reactance. This would reduce the power capability of most lines and cause issues even with fairly short (50mi) fairly low amperage (1000A) lines. 4. Due to (3), transmission lines even in a fairly moderate length of ~100 miles would require series capacitor banks and long lines would have to be converted to DC. 5. Generator synchronism would be harder to maintain, the critical clearing times would remain approximately the same on a per cycle basis but since each cycle lasts ~15% as long this might be a problem. Current technology would allow for relays to detect faults at the same amount of power system cycles at 400 or 60 Hz for non-communication based protection schemes but breakers might slow things down a bit and the mechanical contact operation times would be more significant. I'm not really sure how much of a breaker's operation time is related to the mechanical separation of the contacts vs waiting for a current zero to interrupt. On another note, I did get to fondle a t-lines nuts this week. 
|
|
#
?
Jul 9, 2015 04:38
|
|
|
That's all very true and I have no idea why I didn't think of that stuff when writing that post. Thanks  (You would think an electrical engineer would loving know better...)
|
|
#
?
Jul 10, 2015 20:13
|
|
|
I had to explain to an electrical engineer today (who has his PE) why when you use a reference voltage, as far as the equipment is concerned, its angle is zero degrees. Dont feel too bad...... E: taking measurements with a single phase fluke power quality anaylzer TheFargate fucked around with this message at 02:33 on Jul 11, 2015 |
|
#
?
Jul 11, 2015 02:29
|
|
|
TheFargate posted:I had to explain to an electrical engineer today (who has his PE) why when you use a reference voltage, as far as the equipment is concerned, its angle is zero degrees. Dont feel too bad...... How do you like the Fluke PQ meters? Have you used any Gosen-Metrawatt or Dranetz products?
|
|
#
?
Aug 21, 2015 02:25
|
|
|
Three-Phase posted:How do you like the Fluke PQ meters? Have you used any Gosen-Metrawatt or Dranetz products? We only use Fluke for almost everything. I personally think the single phase and three phase PQ meters are good stuff. The only issue we have really run into, is that the clamp on is a bit large for some of our applications. Not a huge deal though, snipping a couple zip ties usually remedies the situation. I have tried another brand but cant remember the name atm. It was very compact and grey. The only other thing thats annoying occasionally, is the Flukes are fairly large but I have small hands so ymmv.
|
|
#
?
Aug 21, 2015 20:53
|
|
|
TheFargate posted:We only use Fluke for almost everything. I personally think the single phase and three phase PQ meters are good stuff. The only issue we have really run into, is that the clamp on is a bit large for some of our applications. Not a huge deal though, snipping a couple zip ties usually remedies the situation. I have tried another brand but cant remember the name atm. It was very compact and grey. The only other thing thats annoying occasionally, is the Flukes are fairly large but I have small hands so ymmv. Awhile back we got a Fluke portable oscilloscope/recorder, it's neat but the interface is clumsy and sometimes it's not always intuitive how to do different things. But it's nice to have isolated oscilloscope channels up to 600V rms or so. Good for things like drives. Other thing that sucks is that the probes that come with it have a connection point for the common, but the little clip at the end of the common is about ten inches long! So if you need to measure to a distant point, you need to get electrical tape and bodge together a longer lead. Unless they have an adapter that goes from the insulated BNC to banana jacks that are compatible with Fluke's industrial Cat-3/4 leads. Three-Phase fucked around with this message at 23:15 on Aug 21, 2015 |
|
#
?
Aug 21, 2015 23:00
|
|
|
"Google translate posted:Last Tuesday a fault occured in the high-voltage grid in Gunzburg, and as a result repairing a generator part of the nuclear power station has become necessary. The reactor should continue working during the works, but the generator has to be taken off the mains for the duration of the repair.
|
|
#
?
Aug 22, 2015 16:52
|
|
|
Three-Phase posted:Awhile back we got a Fluke portable oscilloscope/recorder, it's neat but the interface is clumsy and sometimes it's not always intuitive how to do different things. But it's nice to have isolated oscilloscope channels up to 600V rms or so. I agree, but we use PQ meters for very limited things. We pretty much exclusively use them for measuring current transformer secondary current in differential circuits for high impedance relays. Since these are the only ones we cant just plug our laptops in and get a reading. So its pretty much limited to when I have to do current phasing on a SEL 587z. Some techs do use them for checking CT circuit polarities as well.
|
|
#
?
Aug 22, 2015 22:00
|
|
|
TheFargate posted:I agree, but we use PQ meters for very limited things. We pretty much exclusively use them for measuring current transformer secondary current in differential circuits for high impedance relays. Since these are the only ones we cant just plug our laptops in and get a reading. So its pretty much limited to when I have to do current phasing on a SEL 587z. Some techs do use them for checking CT circuit polarities as well. What kind of CTs do you use for that? I've used both big flexible CTs (0-3000A, with 30, 300, and 3kA scales) as well as much smaller 0-10A and 1-20A clamp-on CTs. I think I've seen saturation on the 0-10A CTs during inrush events. Like a 600:5 CT that sees 3000A inrush and that causes the secondary to go to 25A for a couple of cycles and I don't think some of the clamp-on CTs handle that very well.
|
|
#
?
Aug 23, 2015 01:22
|
|
|
Three-Phase posted:What kind of CTs do you use for that? I've used both big flexible CTs (0-3000A, with 30, 300, and 3kA scales) as well as much smaller 0-10A and 1-20A clamp-on CTs. I think I've seen saturation on the 0-10A CTs during inrush events. Like a 600:5 CT that sees 3000A inrush and that causes the secondary to go to 25A for a couple of cycles and I don't think some of the clamp-on CTs handle that very well. All depends on the voltage the equipment is rated for. I work with 3000:5 and 2000:5 CTs a lot. We try to set it up so we use the max ratio so we get the most accurate readings. Off the top of my head, the smallest cts we generally use are something like 300:5 on our 4kv circuits. Don't quote me on that though cause I mainly deal with transmission/sub-transmission. I actually do the construction side so I install and help commission equipment. I generally work on 69kv to 500kv stuff. We have a separate group that does distribution upgrades. As far as the little clamp on cts, we very rarely use them. All our CTs are breaker or transformer mounted, except for 4kv which are a slightly different story.
|
|
#
?
Aug 23, 2015 18:29
|
|
|
This seems like a decent place to ask this. I have a 3000A feed that the client wants to take underground and terminate in a single 36"x48" section with a main and a 1000A sub-feed breaker. They don't want to use bus duct, despite my recommendations. Manufacturer says they can build a single-section board that works for this, but a 3000A feed is (8) sets of 500MCM in 3.5" conduit, so I'm worried that the contractor isn't going to be able to terminate all of that copper in a single section (utility requires bus duct for secondary this size, but it's not a utility transformer). Do you think my worries are justified, or should I trust the contractor when they say they can do this?
|
|
#
?
Sep 30, 2015 06:05
|
|
|
Papercut posted:This seems like a decent place to ask this. I have a 3000A feed that the client wants to take underground and terminate in a single 36"x48" section with a main and a 1000A sub-feed breaker. They don't want to use bus duct, despite my recommendations. Manufacturer says they can build a single-section board that works for this, but a 3000A feed is (8) sets of 500MCM in 3.5" conduit, so I'm worried that the contractor isn't going to be able to terminate all of that copper in a single section (utility requires bus duct for secondary this size, but it's not a utility transformer). What is the voltage? We handled 500kcmil triplex that was rated for 15kV, and that stuff had an absolutely miserable turn radius and you had to deal with shielding too. I'm assuming this is 480 or 208V?
|
|
#
?
Oct 19, 2015 01:09
|
|
|
I think my favourite reason for a power station trip prior to this was "jellyfish ingress". Apparently, if you let them clog your cooling water intake, this leads to pain and suffering.
|
|
#
?
Oct 19, 2015 22:23
|
|
|
Three-Phase posted:What is the voltage? We handled 500kcmil triplex that was rated for 15kV, and that stuff had an absolutely miserable turn radius and you had to deal with shielding too. I'm assuming this is 480 or 208V? It's 208V secondary yeah. Too late anyway, but I spec'ed a pull section just because I figured there's no way they could do it in a single section footprint.
|
|
#
?
Oct 20, 2015 00:58
|
|
|
RDevz posted:I think my favourite reason for a power station trip prior to this was "jellyfish ingress". Apparently, if you let them clog your cooling water intake, this leads to pain and suffering. The old oil-fired Cape Canaveral power plant (demolished in 2010, and replaced with a natural gas combined cycle plant,) used to get enormous runs of shrimp on the condenser cooling water intake screens. The ops guys would go out with plastic trash cans and a push broom, put the broom against the screen drum, and turn it, scraping a continuous stream of enormous, delicious shrimp into the trash can. They could do two or three big cans a night, probably two or three hundred pounds worth, when the tides were right, and the shrimp were out. I ate a lot of shrimp, growing up. 
|
|
#
?
Oct 20, 2015 02:33
|
|
|
We have to watch out for frazil ice when things get really cold. Apparently massive icicles on the moving trash racks makes a hell of a noise.
|
|
#
?
Oct 20, 2015 03:21
|
|
|
RDevz posted:I think my favourite reason for a power station trip prior to this was "jellyfish ingress". Apparently, if you let them clog your cooling water intake, this leads to pain and suffering. this is no loving joke man. my brother's ship had this more than once, not a fun situation at all
|
|
#
?
Oct 20, 2015 04:04
|
|
|
So I was driving past a shopping strip I used to work in. The place was mostly dark, except the sign at the street was lit up (very dimly compared to normal), and a couple of storefronts had fully working lights. AFAIK only one transformer serves the property (I used to work in that shopping center). The Albertsons (grocery store) had some lights that made it look like a rave was going on inside - most of them were dim, some were incredibly bright and strobing off and on. The traffic light in front of it was barely glowing all of the lights and looked like it kept resetting itself (would weakly flash red on all 4, then go to all lights barely lit up, etc). A handful of places (half?) had at least semi-working lights. Most of them were either flickering or way too bright compared to normal. The majority of signage on the building was either flickering or dark How common is it to drop 2 out of 3 phases? That's the only explanation I can come up with for this. The apartments behind it were a lot of the same - random apartments had some power, most didn't.
randomidiot fucked around with this message at 06:46 on Oct 23, 2015 |
|
#
?
Oct 23, 2015 06:43
|
|
|
|
| # ? May 12, 2024 19:55 |
|
|
That really depends on the electric company. For us, if one phase goes down, the other 2 do as well. Then if its a 13kV circuit, the system will automatically try to restore power to as many customers as possible. If its a 4kV circuit, you wont get power back until the lines are repaired. Other than something taking out 2 phases (i.e. a falling branch or some such) no clue how you could lose 2 phases.
|
|
#
?
Oct 23, 2015 12:03
|
|