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I would, as a grown man, pay a respectable amount of money to attend Industrial Electricity Summer Camp. Sadly, I imagine the waiver they'd make my wife sign would be pretty impressive. For a bit of content, a question: Are there enough advances in the technology that there's a rift between old-guard guys that want coal-powered steam driven switchgear and new school kids that want to put everything on computers or whatever? I imagine at this point it's kind of sink or swim as far as adopting new tech, for the old fellas. Jonny 290 fucked around with this message at 10:14 on Jun 8, 2012 |
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Jun 8, 2012 10:09
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Jonny 290 posted:For a bit of content, a question: Are there enough advances in the technology that there's a rift between old-guard guys that want coal-powered steam driven switchgear and new school kids that want to put everything on computers or whatever? I imagine at this point it's kind of sink or swim as far as adopting new tech, for the old fellas. Depends entirely on where you work. I'd say the answer in many respects is "yes". However when old-guard people talk, I listen attentively. The one issue with the older folks is that they weren't brought up with the safety mentality we have today. I've heard comments along the lines of "Oh, arc flash, we never had that protective stuff back in the day." (And people occasionally got burned to death because of that.) The other problem is money. It's very hard to change an older, yet reliable system, especially one that can still be maintained, to something new that may or may not work as well, no matter what the vendors say. The work-around to this problem are retrofits. Like if you have an ancient bank of medium-voltage switchgear, the busses and insulators, despite being from the 50s or 60s, might still be in good condition. So you get a retrofit for the circuit breakers. You rack out the old arc-chute/magnetic circuit breakers, throw them in the trash, and install new vacuum-bottle breakers that have fewer moving parts, MUCH higher interrupting capacity, and can still plug into the really old power and control connections that the old breaker had. Jonny 290 posted:Sadly, I imagine the waiver they'd make my wife sign would be pretty impressive. It's not as safe as a complete desk job, but I'd say the stuff myself and others do at work is pretty safe. It's probably far more dangerous each day driving to work than performing testing, maintenance, and troubleshooting. Especially if you have a good crew that understands how to mitigate and communicate the risks involved. The Palo Verde Arc Flash Incident is a good video of a very serious accident (level 3/4 arc flash) that resulted in no injury at all because of proper safety training and equipment. (I did grin at the "BREAKER REMOVED FOR MAINTENANCE" sign over top of the burn marks on the switchgear!) Three-Phase fucked around with this message at 10:49 on Jun 8, 2012 |
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Jun 8, 2012 10:40
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We had a transformer explosion at a sister site recently. The dielectric in the oil-filled transformer had degraded from a leaky cover plate and arced over when it was re-energized following routine PM. The explosion threw the electrician literally 15' through the air, landing in a parking lot about 25'. Fortunately, he was wearing full PPE and walked away with only minor injuries. Wear your PPE, kids! And don't skimp on fluids testing, either.Jonny 290 posted:For a bit of content, a question: Are there enough advances in the technology that there's a rift between old-guard guys that want coal-powered steam driven switchgear and new school kids that want to put everything on computers or whatever? I imagine at this point it's kind of sink or swim as far as adopting new tech, for the old fellas. It's driven a lot of specialization on the engineering and technician side of the house for design/maint/repair, especially for controls, but there really isn't a whole lot of difference in cabling or conduit or lugs or any of the really time consuming stuff that occupies electricians most of the day. The new solid-state equipment operates different internally, but all hooks up pretty much the same way. grover fucked around with this message at 17:44 on Jun 8, 2012 |
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Jun 8, 2012 17:39
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One of the newest things I saw was medium-voltage GIS. Looks pretty safe and reliable, but it looks like it would be an absolute bitch to disassemble and add on to compared to other equipment. I think it was Siemens, they actually had embedded little USB cameras inside the gear that you can connect a computer to so you can visually check the state of the breaker mechanism.
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Jun 12, 2012 01:14
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Watched some motor starting charts recorded at work. Had a medium voltage motor that drew approximately 4000A (peak) line to line on startup. Watching the chart, I could actually see the asymetric components: Current A-B: Had a positive DC component of a thousand or so amperes, that decayed back down to 0Adc after about five cycles Current B-C: No noticable DC component Current A-C: Had a negative DC component of maybe 500A That was pretty wild.
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Jun 22, 2012 00:04
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Cheesemaster200 posted: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. This may have already been covered - been reading the thread from the beginning. But, check out the new electronic trip units on the square D Powerpact H-frame breakers. I recently told a customer to purchase one of these to replace a fixed 90A H-frame breaker in his I-line panelboard. With the right settings it solved his category 3 arc flash hazard problem! I realize you said "most" which still makes you right but this is such a new offering from sqd that most people are not aware of it.
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Jun 23, 2012 00:52
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babyeatingpsychopath posted:
Not sure if anyone else answered this. Didn't see it a page out from when you asked... Logically you are correct - for a given available short circuit you can take a look at the current limiting fuse manufacturer's curve and see what the RMS short circuit let-through is. If it is below 5kA then you can be tempted to say the problem is solved. However, you cannot independently make the logical jump from that to saying that a certain piece of equipment "X", normally rated at 5kA is now no longer over-dutied. for equipment to take into consideration external protective devices in it's short circuit rating it has to have a published "series rating". There are extensive tables that the major equipment manufacturer's have developed to account for these things. A good example is that a non-fused heavy duty disconnect switch from square D is normally rated 10kA, but if fed from a MCC bucket containing a j-class fuse (current limiting) it has a series rating of 200kA. I won't even get into evaluating the short circuit rating of unlabeled industrial control panels, which is a whole world into itself (see UL 508A) but, if people have specific questions about how to evaluate unlabeled panels I can get into that in more detail later. Assuming it hasn't been covered, I'm only to page 5 or 6 in this thread...
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Jun 23, 2012 01:07
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PPoison posted:I see! So the phase to neutral potential will not vary with changed loads. That sounds pretty obvious in fact, since otherwise the light would keep changing in brightness in hospitals and Norway and stuff that use the IT system. god drat now we are getting into some good stuff - system grounding. High resistance grounding, low resistance grounding, ungrounded systems... I really should read ahead to see how much of this has been answered but here goes: on an ungrounded system (floating neutral) if a L-G fault is allowed to remain on the system, the system can be affected by transient overvoltages due to restriking or intermittent ground faults. the intermittent ground faults can displace the L-G voltages to many times their normal value, causing insulation damage and breakdown. There have been many document cases where multiple equipment failures over an entire system have occurred while trying to locate a ground fault on an ungrounded system (NOT EASY TO DO). Incidentally, these over voltages on ungrounded systems have led to the development of resistance grounded systems. A typical high-resistance grounded system lets a small enough current through (IE 5A) on a L-G fault that systems can still run on a ground fault but the system is still tied to ground ENOUGH that the over voltage problem described above does not happen. The key is to keep the fault current through the resistor to a value equal to or greater than the system charging current.
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Jun 23, 2012 01:20
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I got to tour Surry Nuclear Power Plant today. Was really loving awesome climbing around all through the turbine building around the massive piping, heat exchangers, generators, etc., for the two 800MW steam turbine generator systems. Didn't get to go into the reactor containment, building, though 
grover fucked around with this message at 01:32 on Jun 23, 2012 |
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Jun 23, 2012 01:28
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Grover, Did you see the Generator Step up transformer for that? I used to work for a power plant design firm but we never got much over 500MVA Transformer. Curious as to if the standard on that size of unit would be for 3 single phase transformers or to really have a single 3 phase transformer rated at like 1000 MVA?. Also interested in how big the isolated phase bus duct is between the steam turbine generator and the GSU. I'm guessing those generators cant be generating much more than 25kV, which would put the current at around 23kA, assuming these are 0.8 pf machines! That is one hell of a conductor. IPBD has always amazed me.
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Jun 23, 2012 02:15
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Allantois posted:Grover, The reactors are in the breast-shaped buildings; the turbine building is the large building directly south of them. You can see the switchyard pretty clearly, just to the southeast of the turbine building: Google maps link  I found it interesting that the water the plant returns to the James River is only 2 degrees warmer than what it takes in. Also, the intake canal is apparently awesome for fishing because little fish get sucked into the pumps but then grow too big to fit through the gratings and because they have no predators, just get MASSIVE. And the output is a favorite fishing spot, too, because fish thrive so well in the warm water there.
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Jun 23, 2012 02:31
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Based on that picture it looks like three single phase transformers which is not too surprising. If you notice just to the south of the turbine building the three transformers for each of the turbines. These transformers have to be directly adjacent to the turbine because of the MASSIVE current delivered between the generators and the GSU's. That IPBD is probably around 55-60 inches in diameter per phase. You can see it if you look closely. I wonder if these actually have generator circuit breakers installed between the generator and GSU. I doubt it, due to the current level. They would be like 2-3 million dollars each. Interestingly enough historically, generation ability surpassed circuit breaker ability so there is a long history of directly connecting steam turbine generators to transformers like that... Even though you can buy GCB's that large now. My guess is they sychronize with the utility in the switch yard at the 230kV or 500kV level. Can't quite understand what the three smaller structures are to the left of the larger transformers... They look like auxiliary transformers tapped from the IPBD to feed power into the plant. If that is the case there MAY be a GCB inside the building because you would want to isolate the generator when back feeding from the grid when the generator is not online. Allantois fucked around with this message at 02:52 on Jun 23, 2012 |
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Jun 23, 2012 02:50
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Regardless that is a really cool plant. I wish I could tour it. Plants that are lucky enough to have a cooling water source like that and can dump it right back into the bay save a ton of $ on cooling systems. I notice there are no hyperbolic cooling towers so iconic to what people think of when they think of a nuclear power plant.
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Jun 23, 2012 03:04
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Allantois posted:Based on that picture it looks like three single phase transformers which is not too surprising. If you notice just to the south of the turbine building the three transformers for each of the turbines. These transformers have to be directly adjacent to the turbine because of the MASSIVE current delivered between the generators and the GSU's. That IPBD is probably around 55-60 inches in diameter per phase. You can see it if you look closely. The generators themselves were fully enclosed, and on the top floor of the turbine building alongside the turbine assemblies (6 turbines per generator- 2 high pressure and 4 low pressure). With the maze of piping and heat exchangers inside the building, I wasn't able to trace any of the HV cabling within the building. It's amazing just how many ancillary heat exchangers are hanging everywhere to wring an extra few % thermodynamic efficiency from the steam. Since power is so critical to nuclear plants, even when they're shut down, there is probably an auxilliary set of transformers designed to backfeed the building from the grid when the turbines and EDGs are offline. grover fucked around with this message at 03:29 on Jun 23, 2012 |
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Jun 23, 2012 03:21
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How many poles were the generators? Eight or more? Did you take a look at the excitation system? Was the cooling air, water, or hydrogen? I would have loved to see all the auxillary systems the generators must've had. (Lubrication oil, high-pressure jacking oil, blowers, water coolant, and pressurized air depending on the bearing seals.) Are generator circuit breakers an application where you can/must put breakers in series with one another? (I've seen a few medium-voltage applications at >3000A where the solution was, with engineering supervision, to put two circuit breakers in parallel.) Three-Phase fucked around with this message at 03:36 on Jun 23, 2012 |
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Jun 23, 2012 03:27
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Three-Phase posted:How many poles were the generators? Eight or more? Did you take a look at the excitation system? Was the cooling air, water, or hydrogen? Allantois posted:Regardless that is a really cool plant. I wish I could tour it. Edit: Dominion's website has an animation that looks like a pretty accurate depiction of the Surry power plant, as far as # of turbines goes, layout of the components, etc: http://www.dom.com/about/stations/nuclear/nuctour.html grover fucked around with this message at 03:52 on Jun 23, 2012 |
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Jun 23, 2012 03:34
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A good PDF on the Isophase bus duct: http://www.azz.com/sites/default/files/documents/Calvert%20IPB.pdf Crazy because 25kA sounds like a short circuit value not a continuous current rating. If this plant is early 70's there is no way there is a GCB unless it was a recent retrofit. Three-phase, I've never seen series GCB on a power plant. ABB, Mitsubishi, and Hitachi all make a range of them large enough now that you should be able to find one as large as you need it. They are just drat expensive. I remember a price circa 2008 of about $500k for approx 7000-8000A version. http://www.abb.com/product/us/9AAC30200091.aspx
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Jun 23, 2012 03:50
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Three-Phase posted:Watched some motor starting charts recorded at work. Had a medium voltage motor that drew approximately 4000A (peak) line to line on startup. Watching the chart, I could actually see the asymetric components: Cool real-world example of something I was just doing today in SKM. I was putting in a motor protection relay and added the asymetric contribution to the motor starting curve. In the program it defaults to a decay time of 0.1s. That is pretty drat close to the 5 cycles you observed!
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Jun 23, 2012 04:16
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grover posted:auxilliary set of transformers designed to backfeed the building from the grid We have separate transformers that can supply class 4 power either directly from the generator or from the grid. The unit service transformer is so small that it is completely hidden by the MOT enclosures. We run 3 single phase transformers as main output transformers and the sync breakers are in the switchyard not on the IPB.
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Jun 23, 2012 05:00
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Allantois posted:Cool real-world example of something I was just doing today in SKM. I was putting in a motor protection relay and added the asymetric contribution to the motor starting curve. In the program it defaults to a decay time of 0.1s. That is pretty drat close to the 5 cycles you observed! What sort of motor were you protecting? This was a medium-voltage synchronous with a reduced-voltage (impedance) start.
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Jun 23, 2012 11:47
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Three-Phase posted:I'd be interested in hearing about what you have. At 5000HP you could have synchronous or induction motors. I'm guessing no less than 2400V (for 5000HP 2.4kV may mean parallel cables), maybe 4160V or 7200V? The 2000HP motors are running at 4160V and use a non-reversing full voltage brushless exciter starter. Does anyone know how this starts the motor? I'm not very familiar with synchronous motors. I have the single line for the larger SAG mill attached, two 5500HP motors but I don't really know what's happening to them. Looks like they're connected somehow to two Delta-delta/wye, has anyone seen anything like this before and care to give a brief explanation??  Each motor is connected with 16 x 1000mcm cables in a bus duct, pretty crazy stuff! They have a Switchroom dedicated to this mill and it's processes.
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Jun 26, 2012 22:15
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Meow Meow Meow posted:The 2000HP motors are running at 4160V and use a non-reversing full voltage brushless exciter starter. Does anyone know how this starts the motor? I'm not very familiar with synchronous motors. The brushless exciter bolts directly onto the shaft of the motor, and acts like a little DC generator that makes the field inside the motor. A synchronous motor cannot "start itself" because if you apply the field (the DC electromagnet on the rotor) when the speed is zero, no torque will be produced. So you need to do two things: 1. Have a different motor, a pony motor, get the motor close to synchronous speed and then energize the field to take over 2. Have the motor built with armitissour windings - basically this is an induction motor's squirrel-cage built into the induction motor. When the speed is less than synchronous, the armitissour windings provide the starting torque. As you get closer to synchronous speed, the armitissour windings provide less and less torque, and by energizing the field, you provide the torque to lock the motor in synchronism. When synchronized, almost no current flows through the armitissour windings. I have never seen this kind of transformer configuration before, but I have a few ideas: 1. It looks like the two transformers are identical: same MVA ratings, same voltages in/out, same %Z. The two parallel Wye connections go to one motor, and the two parallel delta connections go to another motor. 2. Both motors have some kind of starter or variable-speed drive, indicated by the little triangle symbol. This is my theory: When you have a transformer with two secondary windings, Delta and Wye, there is a 30 degree phase shift. This is really useful when you have SCR drives. If you don't have a phase shift between the drives, it's possible that if both drives are operating at nearly the same speed/power, you can fire the SCRs on each drive at the same time. That may introduce more noise/transients into the power system. It's like two soldiers marching across a bridge with the same LEFT-RIGHT-LEFT-RIGHT at the same time. Due to the phase shift between the two drives, it's not as likely that both will be firing at the same time - it's like the break-step bridge. I've seen systems where there were clusers of three drives, and each drive had a zig-zag transformer that gave a different phase shift: Drive A: +15 degrees Drive B: 0 degrees Drive C: -15 degrees I don't think the two are there for the purpose of redundancy, because even if you power off one transformer via the isolation switch, you'll backfeed the connection via the other transformer. It would be very important to NEVER do any maintainance downstream of, say, the LEFT open switch with the RIGHT open switch closed. (Grover - let me know if this assumption is correct.)
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Jun 27, 2012 10:32
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Three-Phase posted:I don't think the two are there for the purpose of redundancy, because even if you power off one transformer via the isolation switch, you'll backfeed the connection via the other transformer. It would be very important to NEVER do any maintainance downstream of, say, the LEFT open switch with the RIGHT open switch closed. (Grover - let me know if this assumption is correct.) Notice, though: no means of isolation on the secondary. These transformers are ALWAYS in parallel. I think they used two transformers due to some limitation that prevented use of a single larger transformer. Qs. Are the motors redundant, or sequenced that only one will ever be at (or near) full load at any given time? Are they linked together mechanically, in which case they could act as zero-point starters for each other? grover fucked around with this message at 10:44 on Jun 27, 2012 |
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Jun 27, 2012 10:42
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It's hard to read, but if the Wye is 8MVA, and the Delta is 12MVA... 5500HP = 4.10MW (at unity power factor) It looks like both motors could easily operate when only one transformer is energized... I talked to someone at work who said the system I described was "pretty weird". But weird electrical stuff excites me (pun partially intended) so it's OK. 16x1000kCmil for a 5500HP motor is insane. Meow, you're not pulling our legs, are you? Three-Phase fucked around with this message at 20:40 on Jun 27, 2012 |
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Jun 27, 2012 20:33
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Three-Phase posted:The brushless exciter bolts directly onto the shaft of the motor, and acts like a little DC generator that makes the field inside the motor. It was explained to me that brushless excitation is accomplished by having a transformer winding and a set of diodes in the rotor itself. The exciter is simply an AC voltage regulator that feeds into the primary of the brushless exciter and it is converted to DC by the diodes.
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Jun 27, 2012 21:07
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Three-Phase posted:The brushless exciter bolts directly onto the shaft of the motor, and acts like a little DC generator that makes the field inside the motor. Ahh, thanks for clearing the synchronous motor starting, I'll have to look into these mills a bit more and see what method they use to start. Having the motors have a 30% phase shift makes sense, I believe both motors always run at the same time to get the mill spinning. There's a couple different kinds of filters attached to the bus, 5500hp motors would produce quite a lot of noise and harmonics. Three-Phase posted:It's hard to read, but if the Wye is 8MVA, and the Delta is 12MVA... I swear I'm not, I'll take some pictures of the motors and the mill itself when I get a chance. The mill is a drum about 30ft in diameter and 10ft deep. It has large plates inside and uses 5" diameter steel balls to do the grinding. It does 80% of the grinding at our mill, it's quite the sight to see it spinning. I think 8/12 MVA corresponds to the ONAN (Oil Natural, Air Natural cooling) and ONAF (Oil Natural, Air Forced cooling). These transformers are ONAN so I think the whole transformer is 8MVA, 4MVA delta and 4MVA wye, assuming balanced loads. Also they're 13.8kV - 705V - 705V, i guess 705V delta and 705V wye? grover posted:I'm kinda stumped, too. My first thought was that it was a soft-starter (as wye connections are often used as soft-starters), but that doesn't explain the cross-connect. Then I was thinking that maybe they used both delta and wye windings in each motor to change them from 3-phase to ~ 6-phase like you see in a lot of 12-pulse power supplies (only other time I've seen transformers like that), but that still doesn't explain the cross-connect. The motors are not redundant, both are running when the mill is in operation. I'll have to look into if they're mechanically linked, they're set up motor-mill-motor. It looks like this physically: oOo with o-motor and O-mill. Meow Meow Meow fucked around with this message at 23:48 on Jun 27, 2012 |
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Jun 27, 2012 23:45
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helno posted:It was explained to me that brushless excitation is accomplished by having a transformer winding and a set of diodes in the rotor itself. Yeah, that's a much better explanation. I got lazy. That motor configuration is pretty wild.    Also that one-line diagram is a pretty drat good example of stuff you'd see/use in industry. I work with one and three-line diagrams on a daily basis.
Three-Phase fucked around with this message at 01:05 on Jun 28, 2012 |
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Jun 28, 2012 01:00
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Meow Meow Meow posted:Ahh, thanks for clearing the synchronous motor starting, I'll have to look into these mills a bit more and see what method they use to start. If it's anything like the grinding mills we've done (granted, we always used VFDs on both motors), they are solidly mechanically linked, and one motor is run with a speed regulator (the "master"), the other with a torque regulator (the "slave"), so that both motors are running approximately the same load. I've also heard of a dual-winding motor with a 60deg phase shift between the two windings, to improve the "linearity" of the torque produced (in essence, a 6 phase motor). They use two VFDs, each one driving one winding), generally on separate transformers. To me, that diagram shows a system similar to what I described, looks like two SCR drives (cycloconverters? not really familiar with SCR based AC devices) and redundant transformers. I'd certainly suspect them to be mechanically linked (though perhaps with a way of free-wheeling one if you lose a motor). Three-Phase's explanation of the delta-wye reasoning makes sense to me (though I've always seen SCR devices on individual transformers).
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Jun 28, 2012 10:45
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I'm assuming weather like this is pretty much the worst oh-poo poo load a power grid can have. Thanks for keeping my house cool, Electricity (and the men who work with you)!
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Jun 29, 2012 18:39
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Jonny 290 posted:I'm assuming weather like this is pretty much the worst oh-poo poo load a power grid can have. The thing is that it's possible to prevent the grid from completely becoming overwhelmed by doing things like rolling blackouts and brownouts. What's bad is if something unexpected happens when the system is already very stressed.
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Jun 29, 2012 23:52
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Three-Phase posted:The thing is that it's possible to prevent the grid from completely becoming overwhelmed by doing things like rolling blackouts and brownouts. What's bad is if something unexpected happens when the system is already very stressed.
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Jun 30, 2012 00:24
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grover posted:Is that why 75% of Puerto Rico doesn't have power right now? I mean, it's kinda occam's razor, but the news doesn't have much by way of details right now. Well, for one thing, it's an island. When you have a power grid that spans a large area (an entire country, several states, or even a fraction of a continent) problems and changes in the system can be "absorbed". Like if a large generator at a single power plant trips offline, the grid probably can compensate for the loss - you may dip in voltage but the system can respond in a controlled fashion. That's because there are many generators supplying power into the grid. On the other end of the spectrum is a single generator running loads. I've seen generators where the system voltage drops to 0.8PU (80% of the nominal voltage) when a single motor connected to it starts. If you try and start every load at once, it'll easily trip out the generator. What you have to do is add loads in order from largest to smallest, with some time delay between adding loads so the generator/motor can compensate for the loads being added on. It's like having people climb into a boat. You don't want everyone to jump into a little rowboat at once. Or have the really, really fat guy be the last one in. On an island, you don't have a huge area, and lots of generators and even connections to other grids to help keep you stable. If a generator unexpectedly goes down, it could pull the whole island down with it. I believe that there are different power quality standards for islands because it's harder to maintain stable voltage and frequency on a really small power grid.
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Jun 30, 2012 01:05
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Three-Phase posted:The thing is that it's possible to prevent the grid from completely becoming overwhelmed by doing things like rolling blackouts and brownouts. What's bad is if something unexpected happens when the system is already very stressed. Like having effectively a Cat-1 hurricane blast through the Ohio River valley and DC with 3 to 4 hours warning at best?
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Jun 30, 2012 19:16
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Well, it looks like the area I'm in has dodged a few bullets as far as power outages go. This is just me, but usually if my power goes out, or if I see that the voltage is, for whatever reason, really out of whack for more than a few seconds, I go to the breaker box at my apartment and open the breakers. I'm mainly concerned about the voltage surging too high when power is restored or the voltage not coming back on cleanly and causing damage to stuff downstream.
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Jul 7, 2012 15:13
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Is it normal to have water based fire suppression with equipment or were they doing A Very Bad Thing?
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Jul 13, 2012 02:10
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less than three posted:Is it normal to have water based fire suppression with equipment or were they doing A Very Bad Thing? I think it's a "where worlds collide" situation. I need to talk to the safety engineer at work today, but I believe that those fire suppression heads will not melt and activate unless it gets really drat hot - something like a simple wastepaper basket fire won't activate them. Or the explosion in the transformer was powerful enough to crack or eject the beads on the sprinkler heads. If you have electrical equipment in proximity to a sprinkler, it's a good idea to take steps to protect the equipment in case the sprinkler goes of, or even if the water line breaks. But if a sprinkler head gets hot enough to activate, it means there's probably bigger problems than some water-damaged switchgear. Water based fire suppression will prevent a building from burning down. You can't just say "I'm not gonna put the required fire suppression system here because I don't want it damaging this switchgear/server/etc." It's simply a necessary tradeoff. You have a fire, and the sprinklers damage a million dollar unit substation for your building (transformer and switchgear combination to send 120/208 and 277/480 throughout the building). Or you can have a fire that gets out of control since it can't quickly be suppressed and you end up having a firefighter die and causing serious structural damage to the building, and then the fire marshal says "Hey, you were supposed to have fire supression here! Now your building's really messed up and a firefighter's dead!" (This is a worst-case scenario.) Now if you have a server room, a single cabinet of equipment can cost a million dollars. Especially if it's automation equipment like an ABB S800 Gateway that you can hold in your hand and can cost more than $10,000. There you might invest in a CO2 system. The problem with CO2 systems is that they can kill people through asphyxiation. At the end of the day, the CIO might say "screw it, it's easier to replace a million dollar's of equipment than deal with a wrongful death lawsuit." Also, if you REALLY have mission-critical equipment, it's best to have to separate supplies in two separate locations. Here's a video of a CO2 system that is installed in an industrial facility activated by a smoke alarm when a fault occurs in the drive. Notice the series of alarms to warn workers that the CO2 system is going to activate and that they need to get out of there NOW. https://www.youtube.com/watch?v=nibB2c9djCo An alternative gas is Inergen - this lowers the O2 level enough to stop combustion, but not kill people. Here's a video of Inergen being demonstrated: https://www.youtube.com/watch?v=uuEylKMvbjw This would be good for highly mission-critical areas like a 911 call center where you want to put out a fire but the workers basically CANNOT leave. Three-Phase fucked around with this message at 11:08 on Jul 13, 2012 |
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Jul 13, 2012 10:59
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I've personally been out to look at the switchgear Fire Protection at a couple plants. They have normal deluges over the Transformers where I've been. The ones I've seen are dry deluges, so you don't get leaks. If you get a fire going, you want it out more than you care about the cost of fixing the units damaged. Similarly, there are deluges over the anhydrous ammonia, but for a low level ammonia leak, you can wash it out of the air. Once it's over some level of ppm where the heat input by the ammonia reaction is making it worse, the FP shuts off. https://www.youtube.com/watch?v=0GG7tuw0CVE
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Jul 13, 2012 17:56
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Commercial requirements have lots of variables, but DoD standards are that all rooms, including data centers, comm equipment rooms, power rooms, etc., must have wet pipe sprinklers. (Dry pipe preaction sprinklers are only permitted in very special conditions, like unconditioned mechanical rooms where the pipes could freeze and burst.) The theory is that the sprinklers are only going to activate when there's actually a fire, and even then, only the sprinklers nearest the fire are going to activate- it's not like hollywood where the whole building goes up; each sprinkler head is only going to activate when the glass cylinder holding the valve shut gets hot enough to explode, and when that happens, you've probably pretty much write off anything under it already anyhow. Modern dry-gaseous fire protection systems (like FM200) are often used in sensitive areas with lower thresholds for activation to extinguish fires before the sprinklers discharge. They're not legal as the sole protection system, though; sprinklers are still required. But they're awesome for limiting water damage. It doesn't smother the fire like CO2, but chemically interrupts the flame. If you're in the room when it goes off, it's not going to kill you, but it's apparently extremely uncomfortable, to say the least. The video above is great and all, but you're not going to be reading a book through it. The easiest solution if you're worried about water damage to switchgear is to spec everything with a NEMA-3 enclosure, but that kinda defeats the point of having sprinklers. In all but the most sensitive applications, any electrical system subject to a deluge sprinkler should be interconnected into the fire suppression system to shut off during a discharge anyhow. When it's all said and done, it's a lot easier to replace damaged equipment than damaged equipment AND a building that burned down around it. grover fucked around with this message at 22:28 on Jul 13, 2012 |
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Jul 13, 2012 20:14
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There's also water mist sprinklers. quote:With no water mist protection, temperatures ranged in the 600-1000zC range. Fire spread was rapid vertically, then horizontal spread was eventually accomplished at peak temperature, with flames extended up to four meters above the module, and smoke reaching 100% in the test room in 20 minutes. Damage to the switchgear was considerable.
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Jul 13, 2012 21:58
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less than three posted:Is it normal to have water based fire suppression with equipment or were they doing A Very Bad Thing? We run into the same thing with our datacenter (we use dry-pipe sprinklers). If something has caught fire to the point where we didn't catch it with our HSSD and manually resolve the issue before it became a raging inferno, the water damage from the one or two sprinkler heads that will actually discharge is going to be a lot easier to deal with than a building that no longer exists. It also means that the cabinet that caught fire is probably already a pile of slag anyway.
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Jul 13, 2012 22:05
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