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I'd give their tech support a shout.
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Apr 11, 2013 22:45
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Cheesemaster200 posted:I have a five section 4160V ring bus fed from five paralleled transformers of equal impedance and size. Loads are out of balance to a degree on some busses versus others, but nothing that major. The bus itself can handle the full load amps of four of the transformers. Looks like you got an impedance messed up, maybe the cable from transformer 4 to the bus? Tap settings on the transformers are also equal? Sometimes the project is just broken and it stops making sense. Create an empty new project, go to Project->Merge and select your old one. This will copy all data but will fix most glitches that load flow especially seems to suffer from.
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Apr 11, 2013 23:37
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When you were putting it together, did you clone (I think it's called clone) the transformers and the cabling so they were all exact copies of one another? I agree with Dancer to check the cable impedance as well. (This is mainly to eliminate variables, not solid troubleshooting.) Also, are all five of the circuit breakers tying the ring buses together closed, or is one of the breakers open? But I don't think the transformer should disappear. That's pretty weird. 
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Apr 12, 2013 01:38
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Having worked for one of SKM's competitors and knowing how these software packages work, here are my brief statements: - ALWAYS RUN loving POWER/LOAD FLOW!!!! This is how you determine if your design/model is feasible in the real world. If poo poo don't converge, you hosed up! - Trust me, the Chinese/Indian PhDEEs who code the software know their poo poo more than you do. They may not be able to do a project, but they will loving own your rear end on theory. Bottom line, if there are issues, it is most likely on you, not them. (but always challenge SKM, they really are the bottom rung for these types of programs).
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Apr 12, 2013 06:42
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SeaBass posted:(but always challenge SKM, they really are the bottom rung for these types of programs). B..b.but they're chosen by 39 of 40 top engineering firms in the world... A little while back I had a training by SKM in California and was quite surprised that the people you email with for support are pretty much the entire company, there's maybe 15 people in total. That would explain why it looks like it's made for Windows 95. Lucky for them they're industry standard so most of my customers will either ask for SKM or don't care. What competitor did you work for?
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Apr 12, 2013 08:44
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SeaBass posted:(but always challenge SKM, they really are the bottom rung for these types of programs). My employer maintains licenses on several modeling programs and we have only one client that requires SKM. ETAP seems to be more popular, but as I understand things it's much more expensive. I find ETAP easier to use and doesn't look like dogshit, compared to SKM. However, the fact that a single SKM or ETAP project is actually a folder full of inter-dependent files is pretty annoying. It makes transporting a model between engineers pretty cumbersome. Does anyone have experience with Easypower? We just got a license for that and out of all the programs I've used (SKM, ETAP, ASPEN, and now Easypower) it's the only one that doesn't look like it started in the DOS days. Also an entire project is contain in one file, similar to ASPEN OneLiner but have features more inline with SKM/ETAP. Pretty slick and simple. I'd be interested to hear what other folks think of it. Anti-Hero fucked around with this message at 11:09 on Apr 12, 2013 |
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Apr 12, 2013 11:06
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Cheesemaster200 posted:I have a five section 4160V ring bus fed from five paralleled transformers of equal impedance and size. Loads are out of balance to a degree on some busses versus others, but nothing that major. The bus itself can handle the full load amps of four of the transformers. Just remembered this - do you have some impedance between the busses? Circuit breakers by themselves have no impedance, and SKM gets cranky in you do things like connect busses together with no impedance (typically a cable or bus).
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Apr 13, 2013 03:10
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Pvt Dancer posted:What competitor did you work for? I used to work for EDSA (now Power Analytics) on the DesignBase product. Unfortunately the company is going down the shitter. Once the VP of engineering and consulting retires in the next year or two, I think the company will fold.
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Apr 13, 2013 03:13
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Three-Phase posted:Just remembered this - do you have some impedance between the busses? Circuit breakers by themselves have no impedance, and SKM gets cranky in you do things like connect busses together with no impedance (typically a cable or bus). Does it get cranky, or just flat out refuse to let that connection happen? I think it's the latter. Anti-Hero fucked around with this message at 19:08 on Apr 13, 2013 |
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Apr 13, 2013 03:13
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Three-Phase posted:Just remembered this - do you have some impedance between the busses? Circuit breakers by themselves have no impedance, and SKM gets cranky in you do things like connect busses together with no impedance (typically a cable or bus). It won't let you connect them together if there is no impedance. Everything *should* be working from the perspective of mechanics. I think there is a bug in the programming or I am missing some setting somewhere. I sent the model to SKM to have them troubleshoot it.
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Apr 13, 2013 16:18
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So I have kind of a general question, and I'm not sure if this is the place to ask it but it seems like a good starting point. I'm doing an art project about a local power plant, and it would be really awesome to have some sort of map or diagram that describes how the plant is connected to the grid, where the electricity it produces goes, who is using most of the power, fuel sources, demand over time...that kind of information. Does anything like this exist as an industry standard kind of document? If so, what is it called? And if not, what should I ask the power company if that's the kind of information that I'm looking for so they know what I'm talking about?
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Apr 18, 2013 01:01
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penneydude posted:So I have kind of a general question, and I'm not sure if this is the place to ask it but it seems like a good starting point. As far as the transmission of power goes, there are two different diagrams for this sort of thing: a one-line diagram and a three-line diagram. The high-level one would be a one-line diagram showing the connections from the generators to the switchyard to the transformers and out into the transmission lines that take the power elsewhere.  Source: http://commons.wikimedia.org/wiki/File:One-line_diagram.svg
This is a one-line diagram. In reality there are THREE of everything in that diagram. Each breaker has three poles, each bus has three sections, each transformer has three sets of each winding. The phases are typically labeled A, B, and C. In electrical power transmission, usually everything is in a set of three lines, called a three-phase system. A three-line diagram will show the same system as a one line, except it'll slow all three lines. For simplicity, you'll want to stick to the one-line diagram. SCADA (supervisory control and data acquisition) systems (the computers that run the plant and the power grid) may have one-lines on the screen that show the amount of power going to different locations. The ones I've seen have color codes for the bus voltages in places like substations where power comes in at 345kV or 138kV and goes out at 69kV, 35kV, 13.8kV, or 4160V. However... Asking for these diagrams might cause some serious heartburn. I haven't directly dealt with this thing, but there may be concerns about system diagrams like that being potentially used to sabotage the electrical or SCADA system. Similarly things like asking for plant plans or schematics may be absolutely forbidden. However (part 2) I really like the idea, and we could probably rig up an accurate (yet fake for the facility in question) diagram, if that's an option! Also, I like that you're going for the realistic stuff instead of the typical "make poo poo up" approach to electrical system so many artists (at least in things like video games) seem to use! As far as demand over time, you might be able to get data from their SCADA system or a chart showing demand. Maybe as a CSV file. It'll probably list the bus voltage, megawatts (real power), megaVARs (volt-amps reactive, reactive power). They'd be concerned with both the total power consumed (energy), as well as the power consumption over time, like when everyone gets home from work and turns on their ovens conditioners and power use surges. Or in the dog days of summer when everyone's using air conditioners, and the motors draw a tremendous amount of reactive and real power. Three-Phase fucked around with this message at 01:43 on Apr 18, 2013 |
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Apr 18, 2013 01:17
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Pretty sure there's like a 0.000001% chance that a power utility would give you that information. A lot of it is going to be proprietary and/or sensitive from a security perspective.
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Apr 18, 2013 02:02
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Wow, thanks for all that! Yeah, I'm assuming that the power company is going to be pretty cagey about releasing that kind of information, but I'm going to ask anyway just to see what happens. If it comes up, is SCADA pronounced skay-duh (long A), or skah-duh (like ska)? Or S.C.A.D.A.? An accurate yet fake for the particular facility sort of approach is an option if I'm unable to get real info from them, sure. It's just a matter of calling it "a generic power plant" as opposed to "Some Company X Blah Power Station." I'll let you guys know what they say.
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Apr 18, 2013 07:12
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"Skay-duh"
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Apr 18, 2013 08:04
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penneydude posted:Wow, thanks for all that! Yeah, I'm assuming that the power company is going to be pretty cagey about releasing that kind of information, but I'm going to ask anyway just to see what happens. If it comes up, is SCADA pronounced skay-duh (long A), or skah-duh (like ska)? Or S.C.A.D.A.? About asking about SCADA (as aforementioned, "skay-duh") system data, screenshots, or information will also cause heartburn. I forgot to mention it, but that sort of thing can also be sensitive. Basically, for a power plant asking for this sort of information is a little similar to asking the people running a bank for a map of the building and the guard patrol schedules. It can potentially be very bad if it falls into the wrong hands or people with malevolent motivations. Someone could potentially investigate the system and determine "If I can cause a fault here or mess with this component, I can severely disrupt the power distribution system or even cause damage to certain components." The concerns are about both hacking attacks or physically breaking into a substation and sabotaging equipment. (I'm not sure if the "Aurora" generator attack is still viable, but I'm assuming it is possible. That's where a generator could be destroyed either through a hacker closing substation circuit breakers out-of-phase, or someone breaking into a substation and using a local command to open/close the breakers and cause serious damage to the generator. Potentially many millions of dollars in damage. And don't mention Aurora!) Sometimes you do need to share electrical drawings with the outside world, like if you want to contract out replacing a large piece of equipment, then the people you work with need those diagrams. At the very least it's a "don't share this" verbal agreement, or it could go all the way up to a formal non-disclosure agreement or having the information shared in a highly secure way. With an art project, it's all disclosed. I'm wondering if you can get transmission system or grid maps from whatever city or town you are in, but again, those might also be sensitive. If you are part of a school or art group, making sure that you have credentials indicating who you're with might help a tiny bit, rather than being a stranger knocking on a door asking for system diagrams. I'd consider checking with the plant's PR or educational outreach people, as they might possibly be able to help work things out and get things that the facility engineers would simply say "Hell no!" to. Three-Phase fucked around with this message at 11:26 on Apr 18, 2013 |
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Apr 18, 2013 11:21
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Your European one-line symbols confuse and perplex me...
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Apr 18, 2013 20:35
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Three-Phase posted:About asking about SCADA (as aforementioned, "skay-duh") system data, screenshots, or information will also cause heartburn. I forgot to mention it, but that sort of thing can also be sensitive. Basically, for a power plant asking for this sort of information is a little similar to asking the people running a bank for a map of the building and the guard patrol schedules. It can potentially be very bad if it falls into the wrong hands or people with malevolent motivations. Someone could potentially investigate the system and determine "If I can cause a fault here or mess with this component, I can severely disrupt the power distribution system or even cause damage to certain components." The concerns are about both hacking attacks or physically breaking into a substation and sabotaging equipment. (I'm not sure if the "Aurora" generator attack is still viable, but I'm assuming it is possible. That's where a generator could be destroyed either through a hacker closing substation circuit breakers out-of-phase, or someone breaking into a substation and using a local command to open/close the breakers and cause serious damage to the generator. Potentially many millions of dollars in damage. And don't mention Aurora!)
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Apr 18, 2013 22:59
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Cheesemaster200 posted:Your European one-line symbols confuse and perplex me... The only one-lines I could get were the European ones. I sort of like them to be completely honest. I've got a question myself here. Check this link: http://turbinesandelectricity.blogspot.com/2012/04/turbines-in-nuclear-power-plants.html Now I can see where the generator is, but what's the deal with that little "building" at the end? I know sometimes you can mount a brushless exciter or connections for an external exciter (slip-rings connected to the rotor) on the far end, but I am mystified by that whole little building. Three-Phase fucked around with this message at 02:40 on Apr 19, 2013 |
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Apr 19, 2013 02:26
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Can't say with any certainty, but my best guess would be that it's a control house.
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Apr 19, 2013 02:48
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I finally got around to reading that Superbowl power outage report . . . One of the worst forensic reports I've ever seen. Basically saying a lot of nothing because the guy doesn't know poo poo about relays or being a protection engineer. S&C is not high end stuff like SEL but hopefully they have enough in their legal budget to sue the poo poo out of that Palmer clown.
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Apr 19, 2013 06:52
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Three-Phase posted:The only one-lines I could get were the European ones. If I still worked for EDSA I'd hook you all up with a copy of the software.
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Apr 19, 2013 06:56
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SeaBass posted:I finally got around to reading that Superbowl power outage report . . . That wasn't the impression I got. It sounds like the S&C relay has an undocumented instability at the settings it was dialed in at that led to the misoperation, but was not the sole reason for it. It's been awhile since I read it but there was a discussion on it several pages back.
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Apr 19, 2013 07:16
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Noctone posted:Can't say with any certainty, but my best guess would be that it's a control house. Makes sense - I'm used to everything being run to a separate control room that has the relaying/monitoring cabinets for large synchronous machines (differential current transformers, stator RTDs, bearing RTDs/TCs, bearing vibe X/Y and thrust) except for the excitation system. Speaking of excitation systems, does anyone know where I can find information about sizing field discharge resistors? It looks like they are sized to match the resistance of the rotor windings, but I'm not sure how the power rating is calculated (to my knowledge they are only inserted into the circuit when starting and on shutdown, so the amount of energy they see is somewhat limited). Three-Phase fucked around with this message at 11:23 on Apr 19, 2013 |
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Apr 19, 2013 11:19
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Three-Phase posted:Now I can see where the generator is, but what's the deal with that little "building" at the end? I know sometimes you can mount a brushless exciter or connections for an external exciter (slip-rings connected to the rotor) on the far end It's a similar setup to what you see on this page: http://www.mhi.co.jp/en/products/detail/turbine_generator_system.html
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Apr 19, 2013 22:33
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Three-Phase posted:Makes sense - I'm used to everything being run to a separate control room that has the relaying/monitoring cabinets for large synchronous machines (differential current transformers, stator RTDs, bearing RTDs/TCs, bearing vibe X/Y and thrust) except for the excitation system. I'd assume you size it based on the maximum power supplied to the field coil - given a constant max excitation voltage and the constant excitation current, assume worst-case (PF of 1.0) and just call the product watts, then build the resistor to handle at least that much plus safety factor. But then again, I'm an embedded systems guy, not a power systems / controls guy... so I may be completely wrong here.
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Apr 20, 2013 00:44
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We have conventional sliprings and still have a little building on the end, we call it the doghouse. At our sister plant with different turbine that is where the main lube oil pump is located. As for the FDR ours are pretty small rated at maybe a few tens of kW. They only get connected for a moment after the SCR`s stop gating and before the 41 field contactor opens.
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Apr 20, 2013 01:46
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That's an awfully big exciter, but these are probably >1000MVA machines. helno posted:As for the FDR ours are pretty small rated at maybe a few tens of kW. They only get connected for a moment after the SCR`s stop gating and before the 41 field contactor opens. Just out of curiosity, do you use an electromechanical contactor for the FDR, or do you insert it using a power semiconductor? The systems I've seen use an electromechanical contactor for normal FDR insertion/removal, as well as a semiconductor-based "crowbar" circuit to insert in the FDR if there's a spike in voltage. (Last lines of defense should that fail are an additional snubber circuit, and a spark gap on the slip rings.) Three-Phase fucked around with this message at 03:24 on Apr 20, 2013 |
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Apr 20, 2013 03:17
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We have two parallel FDR's (0.1 ohms basically 4 inch wide folded sheets of steel) and two de-excitation SCR's. These quickly discharge the field when the exciter is tripped to prevent overvoltage of the stator windings. One of the FDR's has a second SCR which is in the opposite polarity, this is the crowbar circuit. It come's into play if there is pole slipping and the field potential momentarily switches polarity. These units are about 850 MVA. The deex and crowbar SCR's are 77mm. The main SCRS are 100mm units. helno fucked around with this message at 01:47 on Apr 21, 2013 |
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Apr 21, 2013 01:44
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helno posted:These units are about 850 MVA. The deex and crowbar SCR's are 77mm. The main SCRS are 100mm units. Nice. H2, air, or water (heat exchanger) cooled?
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Apr 25, 2013 01:55
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Exciter is all air cooled. Each bridge has a 3 hp fan sucking air through it. The themography guys hate it because the plexiglass air guides stop them from seeing much of anything. The generators are H2 for the rotor with H2 to water exchangers and the stators are direct water cooled.
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Apr 26, 2013 03:11
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Wait, H2 as in hydrogen? Isn't that kind of... Flammable?
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Apr 26, 2013 04:07
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100% or near 100% pure hydrogen is too rich to burn, and it has awesome properties for cooling for a gas.
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Apr 26, 2013 04:58
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John McCain posted:100% or near 100% pure hydrogen is too rich to burn, and it has awesome properties for cooling for a gas. Yeah, hydrogen is awesome. Low viscosity for less drag on rotating parts, great thermal conductivity, a breakdown voltage almost as good as nitrogen, very rapid arc-quenching, and you can generate it on-site from electricity and water. There are some ways that hydrogen is crap. It leaks easily, has a wide flammable range, embrittles certain metals (mostly steels).
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Apr 26, 2013 18:26
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How many RTDs per phase do you typically have in a large generator of that size? I've worked with some 10,000HP motors, and we typically had four three-wire RTDs per phase. You'd read two or three per phase and keep the others as spares in case an RTD failed later in the motor's life. This is the typical instrumentation I've seen for large machines: - Stator RTDs (2 to 4 per phase) - Drive end and opposite end bearing vibration metering (four accelerometers) - Shaft thrust sensing - Bearing RTDs or thermocouples - Bearing oil pressure metering (switch, analog signal, or both) - Airflow detection (Differential CTs and exciter instrumentation not included in that list.) Wiping out bearings on a machine that big would suck. My dad told me about a power failure at a plant where the turbines tripped out, but they also lost oil flow to the bearings. They had to break apart the bearings and replace the rotor because it had effectively friction-welded itself in place. Vibration could lead to even more catastrophic failures. There was a seminar on vibration where they showed a rotating component that had catastrophically failed due to vibration and was thrown through a building wall and landed hundreds of feet away. Could easily have killed someone or caused extreme amounts of plant damage. Three-Phase fucked around with this message at 04:38 on Apr 27, 2013 |
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Apr 27, 2013 04:30
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We have hundreds of temperature measurements. Hundreds in the stator. The rotor temperature is measured indirectly with some voodoo magic (pyrolysate collector). It would take a pretty massive post to describe the basic turbine instrumentation. We have multiple backup oil pumps with diverse power supplies and two independent vibration monitoring systems.
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Apr 27, 2013 15:08
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helno posted:We have hundreds of temperature measurements. Hundreds in the stator. The rotor temperature is measured indirectly with some voodoo magic (pyrolysate collector). I would be interested in such a post. I'm a big fan of huge generators and instrumentation in general, and the specifics of an installation would be really cool.
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Apr 27, 2013 19:24
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I honestly wouldn't know were to begin. I have only worked on a handful of the equipment and it is mostly just various instruments that feed up to an analog turbine governor which moves 20 huge valves as required. Alot of what we use is very old, so lots of pressure and temperature switches with only a handful of analog transducers. The turbine control system is a mostly analog GE system from the mid 70's it is pretty reliable but requires a few of my coworkers to do a lot of calibrations during outages.
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Apr 27, 2013 21:20
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helno posted:Alot of what we use is very old, so lots of pressure and temperature switches with only a handful of analog transducers. The turbine control system is a mostly analog GE system from the mid 70's it is pretty reliable but requires a few of my coworkers to do a lot of calibrations during outages. Is it an old-rear end Bentley Nevada?
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Apr 27, 2013 22:06
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GE EHC mark II for large steam turbines. Hope you really like op-amp's. The reheat/preheat system is pretty cool. Basically it boils down to the fact that nuclear reactors make a shitload of really crappy steam. The steam is not superheated coming out of the boilers and goes into the high pressure turbine pretty wet. The high pressure exhaust is fed into four large pressure vessels that have moisture separators and reheat heat exchangers fed by main steam. With the steam now at a lower pressure with the moisture removed it is actually superheated by this reheat cycle. This goes into the low pressure turbines and then into the condensers. All through this process the steam is bled off between different stages of the turbine to eliminate moisture. This bleed steam is used to preheat the feed water and after all of the stages of preheat the water entering the boilers is already at around 125 C. The preheaters all operate on the principal of reclaiming the latent heat of vaporization so they are tube in shell heat exchangers with the shell fed low quality steam that is condensing on the tubes. It's a bit odd feeling the side of a heat exchanger full of steam that is only at 25 c because it is sub atmospheric. All this preheating/reheating gets us from around 25% thermal efficiency to around 33% with 34% being the theoretical limit based on our boiler output and the condenser input. It seems pretty complicated but most of the preheat system is automatic. There are level controllers on the heat exchangers and as power levels increase the bleed steam demand changes proportionally with feed water flow so level control is all you need.
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Apr 27, 2013 22:54
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