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We have similar failed fuel detection systems. CANDU reactors monitor the individual fuel channels for delayed nuetrons to detect failed fuel. If it is detected we simply fuel that channel till we have removed the failed bundle. Boiler tube inspection and plugging is a massive outage job and I am sure it is similar at all PWR reactors. As to water chemistry we get the added bonus of our PHT and Moderator water containing tritium. We spend alot of time in positive pressure suits to avoid that. Luckily I work mostly on the turbines so I spend very little time "in the bag".
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Sep 23, 2011 01:52
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Just wanted to chime in, I work for a large utility on the West Coast, but I'm not exposed to any of the wonderful engineering grid stuff since I work in Energy Efficiency. "Need to know basis" and all  . Luckily, it's an awesome place to work, and it's surprisingly interesting being on the inside of a utility. This thread is really interesting, it makes me want to tour the gas turbine plant near my office even more 
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Sep 23, 2011 04:58
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helno posted:As to water chemistry we get the added bonus of our PHT and Moderator water containing tritium. We spend alot of time in positive pressure suits to avoid that. Look on the bright side, it's not a graphite-moderated reactor. My pet favourite nuclear reactor design (not yet implemented AFAIK), remains the sub-critical accelerator-driven energy amplifier.
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Sep 23, 2011 06:14
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ANIME AKBAR posted:Just curious, is he doing prepolarized MRI? Yeah.
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Sep 23, 2011 06:20
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Frozen Horse posted:Look on the bright side, it's not a graphite-moderated reactor. My pet favourite nuclear reactor design (not yet implemented AFAIK), remains the sub-critical accelerator-driven energy amplifier. Chernobyl. That design was (is... as it's still running in some places in the eastern bloc...) at least partially moderated by graphite. CP1 was graphite moderated. http://en.wikipedia.org/wiki/Chicago_Pile-1 So were most of the air cooled reactors. http://en.wikipedia.org/wiki/X-10_Graphite_Reactor Graphite as a moderator is scary. http://en.wikipedia.org/wiki/Windscale_fire
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Sep 23, 2011 07:02
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helno posted:Boiler tube inspection and plugging is a massive outage job and I am sure it is similar at all PWR reactors. How bad does Canada want the Bomb that they still deal with these?
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Sep 23, 2011 20:17
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It would actually be pretty tricky to do in one of our power reactors. The candu design is mostly a throwback to a time when we couldn't make the pressure vessels needed for a PWR so we designed around it. That then became the trademark of our design. Edit: We also dont have any fuel enrichment facilities due to our lack of a weapons program so running on natural uranium was a plus. Sadly it will probably never be built again now that the reactor division of AECL just got sold to SNC-Lavlin. That sale essentially gave SNC-Lavlin a few million dollars to lay off about 1000 engineers at AECL.
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Sep 23, 2011 21:02
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Cool video I found: showing the magnetic forces involved in a serious electrical fault. From Ferraz-Shawmut. http://www.youtube.com/watch?v=pSxqVh2RYGU Also, Kaboom! (I don't think he was hurt. Much.) Pulling fuse while current was flowing perhaps? http://www.youtube.com/watch?v=ZjXK8Vhm4Po There are some amazingly dangerous videos on YouTube of kids playing with pole transformers they wired up backwards, too. Speaking of danger... http://www.youtube.com/watch?v=uDB0t5ZL_p0 Shouldn't this guy: 1. Be wearing the outer protective gloves and not wearing just the inner portion 2. Be wearing arc-flash gear This looks to me like an electrical accident waiting to happen. Three-Phase fucked around with this message at 01:41 on Sep 24, 2011 |
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Sep 24, 2011 01:27
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What's a good nuclear engineering textbook you guys used in school? Wikipedia's nice, but I'd like a book I can read to improve my knowledge of the reactor types and keep them straight in my head.
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Sep 24, 2011 02:45
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Three-Phase posted:Cool video I found: showing the magnetic forces involved in a serious electrical fault. From Ferraz-Shawmut.
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Sep 24, 2011 03:17
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That's a very interesting video. How do current-limiting breakers and fuses work? As I understand it, a regular fuse is a length of wire made of a low-melting alloy with sufficient resistance so that it will melt due to resistive heating above its rated current. Other added tricks involve the wire being under spring tension to widen the gap rapidly to prevent arcing. What gets added to give it magic current-limiting powers? If it's just a 1-ohm resistor in series, I'm going to be disappointed.
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Sep 24, 2011 04:00
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Frozen Horse posted:That's a very interesting video. How do current-limiting breakers and fuses work? As I understand it, a regular fuse is a length of wire made of a low-melting alloy with sufficient resistance so that it will melt due to resistive heating above its rated current. Other added tricks involve the wire being under spring tension to widen the gap rapidly to prevent arcing. What gets added to give it magic current-limiting powers? If it's just a 1-ohm resistor in series, I'm going to be disappointed. They just work faster. All "current limiting" means, in the context of breakers and fuses, is that they interrupt the circuit and extinguish the arc within 1/2 of a cycle from the beginning of the fault.
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Sep 24, 2011 04:28
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movax posted:What's a good nuclear engineering textbook you guys used in school? Wikipedia's nice, but I'd like a book I can read to improve my knowledge of the reactor types and keep them straight in my head. I don't think I had a single generally available nuclear engineering textbook my entire program! What are you interested in? Mechanical engineering? Physics?
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Sep 24, 2011 10:55
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The Proc posted:They just work faster. All "current limiting" means, in the context of breakers and fuses, is that they interrupt the circuit and extinguish the arc within 1/2 of a cycle from the beginning of the fault. One point - some fuses are "dual element" fuses. They have two separate parts - they have a mechanism that will blow during a sustained overload, and they also have a series of links that will blow in a very serious high-current fault. As far as whipping, I've heard stories about situations where there was a "triplex" bundle of wires in a cable tray, just three wires bundled together every few feet with those really thick tie-wraps. There was a fault and over a half-mile of cable every tie wrap was broken. Also, compared to circuit breakers, fuses have very specific trip curves so you can accurately predict when they'll blow, and that also makes coordination easier. Three-Phase fucked around with this message at 12:11 on Sep 24, 2011 |
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Sep 24, 2011 12:03
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Here are some photos of a blown industrial current-limiting 315A fuse. And yes, it's full of sand, ordinary silica sand, which is used to extinguish the arc quicker.  The trip curves for this fuse are on page 61 here, the set on the right. You can see how different the trip curve looks when compared to a typical circuit breaker of the same size.
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Sep 24, 2011 12:13
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Three-Phase posted:Cool video I found: showing the magnetic forces involved in a serious electrical fault. From Ferraz-Shawmut. Bussmann showed us a similar video when they were in our building for SCCR training. They also showed other effects of not properly protecting things. I can't find the videos online, but they basically showed different breakers and fuses blowing with different interrupting ratings. The class J fuses blew, and the circuit breakers blew up. I'm betting that the 2nd video you posted was someone shorting something in the panel on accident and the protective device wasn't rated for the available fault current. On that note, how common is proper coordination? I'm a controls engineer for a panel shop and I handle one of our larger OEM accounts. We almost never talk to the end user, and just about every panel we build for them is rated for 5kA. We've been putting it on every proposal since we got our SCCR training I mentioned above early this summer (we tried it once before the training but the OEM yelled at us because customers were asking questions...). Since then, I think I've had to design 1 panel that met 75kA. Nobody else has mentioned anything. I'm a little worried that something like this video is going to happen to some poor electrician out in the field, but it's drat expensive to meet these ratings when the OEM gives us peanuts for these panels. And I actually still have questions about SCCR. Am I correct in saying that a combination rating must be tested by UL (i.e. class J fuse in front of a contactor) for it to be valid? Or can I just put a 200kA rated class J fuse with a 5kA let-through in front of a 5kA rated contactor and call it 200kA? I ask this because it's drat near impossible to find properly rated combinations without buying a load of unnecessary equipment. I don't want to buy a $2000 molded case switch to protect a 5HP motor starter when I can use a couple J fuses and a 200kA rated disconnect, but a lot of manufacturers have wacky combinations listed for higher SCCRs.
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Sep 24, 2011 16:49
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DaveSauce posted:And I actually still have questions about SCCR. Am I correct in saying that a combination rating must be tested by UL (i.e. class J fuse in front of a contactor) for it to be valid? Or can I just put a 200kA rated class J fuse with a 5kA let-through in front of a 5kA rated contactor and call it 200kA?
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Sep 24, 2011 17:00
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What is difference between 3-phase 415V vs residential 1-phase 230V mains? What are the reasons they are used as it is?
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Sep 24, 2011 17:33
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movax posted:What's a good nuclear engineering textbook you guys used in school? Wikipedia's nice, but I'd like a book I can read to improve my knowledge of the reactor types and keep them straight in my head. Like the other guy said, there aren't any good NukeE textbooks. That said, if you're just looking for a basic introduction to reactor technology, http://www.amazon.com/Nuclear-Engineering-Handbook-Mechanical-Aerospace/dp/1420053906/ref=sr_1_5?ie=UTF8&qid=1317083893&sr=8-5 isn't terrible, as long as you're already fluent in engineer-ese. It's got a decent overview of the major western-world reactors, some history of reactor and auxiliary systems design, and a little bit of reactor physics at the end. My degree is in chemistry, so it was one of the many books I read after coming to work in nuclear land to figure out how things actually work. Ossetepo fucked around with this message at 01:58 on Sep 27, 2011 |
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Sep 27, 2011 01:53
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Three-Phase posted:Speaking of danger... Yes, he should. Speaking of electrical accidents, we've had a good one here lately. A guy was checking voltage on a new transformer (4160V->460V stepdown transformer), and he put a rotation meter (to check phase rotation) on the output, and then closed the breaker feeding it. Meter blows up. Then he puts his voltmeter on the output terminals (while holding it, not wearing all the gear, but had gloves and safety glasses, IIRC) and found out the hard way that it was a 4160->4160 isolation transformer, not a stepdown. Meter was a total loss. He was fine, but a bit shaken up.
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Sep 27, 2011 03:27
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modig posted:Yeah. Let me guess, Stanford? If so you're lucky as hell to work with some of the best engineers in MRI. I'm jealous. ANIME AKBAR fucked around with this message at 04:38 on Sep 27, 2011 |
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Sep 27, 2011 04:31
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ANIME AKBAR posted:Let me guess, Stanford? I think they were working on pre-polarizing high field MRI. This is low field MRI using room temperature magnets and cryogenic magnetic field measurements, instead of room temperature measurement and cryogenic magnets.
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Sep 27, 2011 04:40
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freeforumuser posted:What is difference between 3-phase 415V vs residential 1-phase 230V mains? What are the reasons they are used as it is? 415? You're from Europe, right? With a three-phase system you have three wires that have a potential between each other (A-B, B-C, C-A) and optionally a neutral (A-N, B-N, C-N) as a fourth wire. With a (US) single-phase system, you have two 120V lines and a neutral, 120V from either line to neutral, and 240V between BOTH lines. Three phase is generally used for larger applications - industrial, commercial, and power transmission. KaiserBen posted:Yes, he should. Speaking of electrical accidents, we've had a good one here lately. A guy was checking voltage on a new transformer (4160V->460V stepdown transformer), and he put a rotation meter (to check phase rotation) on the output, and then closed the breaker feeding it. Meter blows up. Then he puts his voltmeter on the output terminals (while holding it, not wearing all the gear, but had gloves and safety glasses, IIRC) and found out the hard way that it was a 4160->4160 isolation transformer, not a stepdown. Meter was a total loss. He was fine, but a bit shaken up. Oops! He didn't check the nameplate?
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Sep 28, 2011 00:00
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DaveSauce posted:On that note, how common is proper coordination? It is not as common as it should be, but with OSHA being more assertive about assessing arc flash hazards, design engineers will be more diligent about protective device evaluation and coordination. Or they can pay me to do it for them  Honestly, for all of the reports I have reviewed, less than half are done correctly and that is because the systems are so small there is little room for error. The larger the system, the more room for something to get overlooked or not considered as a fault current contribution.
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Sep 28, 2011 00:13
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SeaBass posted:Honestly, for all of the reports I have reviewed, less than half are done correctly and that is because the systems are so small there is little room for error. The larger the system, the more room for something to get overlooked or not considered as a fault current contribution. On our equipment we have bus protection relaying, so if there's a fault detected, not only does the bus' circuit breaker trip, but every large machine also connected to the bus simultaneously trips off as well. (I think that's an 86 relay.)
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Sep 28, 2011 00:17
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Three-Phase posted:415? You're from Europe, right? Or Australasia. Interesting thread, I love reading about all the hardware.
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Sep 28, 2011 05:16
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SeaBass posted:It is not as common as it should be, but with OSHA being more assertive about assessing arc flash hazards, design engineers will be more diligent about protective device evaluation and coordination. Or they can pay me to do it for them My experience with industrial coordination is much the same. Fuses coordinating with molded case breakers are incredibly rare. I'm more of a distribution/transmission protection engineer where coordination is generally pretty straight forward. I recently worked on coordinating an industrial installation where all the 480V circuit breakers were UL short circuit rated, and not ANSI rated. The consequence of only performing UL testing is that a hard-coded instantaneous trip must present. If you perform ANSI tests you can dispense with this as you've proved the breaker won't fail to trip on a high enough fault current. The result is that nothing was going to coordinate. It didn't matter if I set the LTPU, LTD, STPU, etc. of the main breaker to coordinate with the feeders, they all had something like a 10 kA non-defeatable inst. function, and the available fault current in the plant was much higher. So I noted in the report that they needed to stop being cheap bastards and replace all this gear with ANSI rated breakers because if they have a fault anywhere in the 480V system it was anyone's guess what was going to clear first. But this is protection, and no one cares about it until it doesn't work.
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Sep 28, 2011 23:39
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Three-Phase posted:On our equipment we have bus protection relaying, so if there's a fault detected, not only does the bus' circuit breaker trip, but every large machine also connected to the bus simultaneously trips off as well. (I think that's an 86 relay.) That is 87B protection. But what if you have a fault outside of that zone? Like on the cable between the machine and the switchgear bus? That's when proper coordination between upstream and downstream devices is critical, and where the most exposure to mis-coordination lies. This is where overlapping zones for differential protection is very helpful, especially in mitigating arc-flash incident energy levels.
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Sep 28, 2011 23:42
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Nerobro posted:Before I go into this to far, I have never seen a motor cooled by imersion in a fluid. H2 cooling seems perfectly sane, as does air. As does running cooling fluids through the stator. I have heard of rotors having slip rings and cooling water too. Believe it or not, some gasoline pumps in cars are cooled by the actual fuel flowing through them. Awesome thread by the way, thinking of questions to ask.
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Sep 29, 2011 04:00
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SeaBass posted:It is not as common as it should be, but with OSHA being more assertive about assessing arc flash hazards, design engineers will be more diligent about protective device evaluation and coordination. Or they can pay me to do it for them The problem is that you can't coordinate most molded case circuit breakers below around 100A, especially for arc flash. If you have low fault currents in your system you are going to have a lot of incident energy at your downstream breakers and coordination is next to impossible without using fuses. quote:I've often heard this could happen and have seen it in video, but had never seen it first-hand until one of the contractors I work with mis-wired a load bank- essentially feeding the full output of a 480V 400kVA transformer into a pair of 30' long #12 control wires. Damned things whipped like crazy! The 2A fuse blew almost instantly, but the magnetic forces from that much instantaneous current was amazing. I also talked to a guy who apparently shorted some control wiring in a generator in a power plant, tripping the output breaker and turbine. This in turn tripped out the other generators (as the load was spread to them), which tripped out the plant, which tripped out all of Guatemala City, Guatemala. Don't know if it was for real, but I found it funny.. Cheesemaster200 fucked around with this message at 17:23 on Sep 29, 2011 |
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Sep 29, 2011 17:06
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rainwulf posted:Believe it or not, some gasoline pumps in cars are cooled by the actual fuel flowing through them. They are, they are also typically reciprocating pumps, so the same action that actually pumps the fuel is not wasted on "moving the armature" through the fluid. It's a clever set of design choices!
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Sep 29, 2011 19:27
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A question to ask of the Op, or relevant members, what are the typical specs of station batteries? Size and whatnot? Like all things industrial, im assuming they are massively supersized versions of the battery in your car, but im just curious as to HOW supersized they are!
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Sep 30, 2011 04:17
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Nerobro posted:They are, they are also typically reciprocating pumps, so the same action that actually pumps the fuel is not wasted on "moving the armature" through the fluid. It's a clever set of design choices! I have changed many fuel pumps on American and Japanese cars and have never seen a a reciprocating pump. they have all been standard brushed DC motors that drive a gear type positive displacement pump. A few years ago the fuel pump on my Caravan died after 250,000 miles. I cut the pump apart expecting to find worn out brushes. I was shocked to find the brushes still at 50%, but the commutator had worn away to the point there was no more copper left, just the fiber insulating material.
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Sep 30, 2011 04:19
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rainwulf posted:A question to ask of the Op, or relevant members, what are the typical specs of station batteries? By station batteries, do you mean backup DC power source batteries at a generating station or substation, or load leveling batteries? I can talk at some length about the first, but know fairly little about the latter.
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Sep 30, 2011 04:43
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The last fuel pump i pulled apart was the EFI pump for a honda, and it was a strange kind of turbine pump that used two wheels with small vanes on the outside. It wasnt positive displacement, which was even weirder. This is the closest i have come to finding the exact type of construction. http://www.freepatentsonline.com/6799941.html here is a better image and basically the same as the one i pulled apart. http://www.tradekorea.com/product-detail/P00019222/Fuel_Pump.html Anyway, back to electricity!!! rainwulf fucked around with this message at 04:47 on Sep 30, 2011 |
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Sep 30, 2011 04:45
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Ossetepo posted:By station batteries, do you mean backup DC power source batteries at a generating station or substation, or load leveling batteries? I can talk at some length about the first, but know fairly little about the latter. any/both? backup dc power source at a station, is that backup for the station itself? or backup for generation capacity? are there batteries even that big?
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Sep 30, 2011 04:48
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rainwulf posted:any/both? Backup batteries at a generating station or substation are for providing DC power (or AC, via an inverter) to systems that need it in the event of a loss of their normal power source. For example, when the turbine-generator at a nuclear generating station is tripped, it can no longer provide power to the station. The normal 1st backup is the offsite power feed. If offsite power is lost, the 2nd backup(s) are the emergency diesel generators. If one or more EDGs are lost, DC battery banks are designed to provide power to those loads necessary for the safe shutdown of the reactor. I can post more later about the batteries we use for backup if you're interested - they're not really all that exciting, just large series arrays of midsized lead or Ni-Cad cells. Load leveling, or grid storage, batteries are large battery arrays connected to the transmission grid and used to absorb transients in energy demand - if load drops off the grid, such as when an area is blacked out, that energy charges the batteries. If load suddenly increases, such as when large industrial equipment is placed in service, the batteries are depleted. Chemical batteries are not really the preferred way to do this - compared to other energy storage mechanisms, they're expensive and failure prone. I don't really know enough about the battery technology that is used to say much about it. While it would be technically possible to locate a load leveling battery at a generating station, and thus provide backup for that stations generating capacity, that is not normally done. It's more economical and failure-resistant to use an off-site load leveling mechanism to support the grid while bringing online more generation capacity at other plants. The exception to that is for more intermittent generation methods, like solar or wind, some locations do have local energy storage to fill in when it gets cloudy or the wind dies, which gives the grid operators more time to bring the peakers online to hold up the grid.
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Sep 30, 2011 05:42
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On the topic of load leveling, is compressed air energy storage still a thing? We got a brief mention of it being researched while in high school but I've never heard if it panned out.
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Sep 30, 2011 06:24
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I'm a commercial electrician. I love all the stuff that happens on the upstream side of the green boxes on the pads outside. I am also curious about the coordination stuff; It seems to me like you CAN just put a 200kA fuse with 5k let-through in front of 5kA stuff and call it good, but I don't know for sure. I got to tour a decent sized GE co-gen plant about a year ago. I can't remember their output in MVA, but it was a fairly large gas-turbine direct-coupled to a hydrogen-cooled genset with the exhaust feeding a steam turbine coupled to another hydrogen-cooled genset about 200 yards away. The switchgear room in there was neat. I've also been to the building (but not inside) of the Artesia DC-DC link that connects the Eastern grid to the Western grid. Apparently the thyristor bank looks like a giant scientist's apparatus that feeds some plumbing nightmare. The DC bus is just a bunch of 18" copper rods going through the wall, and it looks like oversized plumbing pipe. I wish I could have gone inside. Question time: do you guys still follow the NEC, or is there another standard? I know there are a bunch of sections for "over 600V, nominal" and whatnot, but they're so very short, comparatively.
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Sep 30, 2011 11:01
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rainwulf posted:A question to ask of the Op, or relevant members, what are the typical specs of station batteries? The ones I've seen are set up in arrays that provide about 120VDC for breaker control. They aren't really that large, I've seen them stored in a cabinet about the size of a photocopier.
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Sep 30, 2011 11:22
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