The AI-generated cat pictures thread
08-31-2015, 02:00 PM
Boost Pope
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In 2013, rapper 2Chainz's bus was stopped by police on the way out of Oklahoma City. The initial stop was for a broken taillight.
Police smelt marijuana upon approaching the bus, and requested entry claiming probable cause. 2Chainz and his staff refused police entry to the bus. After a standoff of several hours, the bus (with its occupants) was towed to a police compound where, after the issuance of a warrant, the bus was entered and its occupants arrested.
Police smelt marijuana upon approaching the bus, and requested entry claiming probable cause. 2Chainz and his staff refused police entry to the bus. After a standoff of several hours, the bus (with its occupants) was towed to a police compound where, after the issuance of a warrant, the bus was entered and its occupants arrested.
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08-31-2015, 02:34 PM
Boost Pope
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Huh.
I love the fact that 22.8 kv is "low voltage" on that unit.
At 22,284 amps.
That would be pretty exciting to watch if there was ever a short on the secondary. Is it even possible to implement overcurrent protection at that sort of power level, or do you just say "**** it" and hope for the best?
I love the fact that 22.8 kv is "low voltage" on that unit.
At 22,284 amps.
That would be pretty exciting to watch if there was ever a short on the secondary. Is it even possible to implement overcurrent protection at that sort of power level, or do you just say "**** it" and hope for the best?
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08-31-2015, 03:28 PM
overcurrent protection usually consists of the relays seeing something they don't like and tripping breakers to de-energize equipment. response time is usually measured in cycles, so "usually" the transformer will be de-energized before serious damage occurs.
If it does not work, notice that there are 15,000 gallons of mineral oil in the main tank that will probably take 2 weeks to burn up. that being said, I don't hear of a lot of faults causing transformers to fail.
usually what causes failure is the paper insulation breaking down over time. micro arcs in the oil tends to form acetylene gas, so if you see elevated gas compounds in an oil sample, you know it is time to replace or shut down the bank.
If it does not work, notice that there are 15,000 gallons of mineral oil in the main tank that will probably take 2 weeks to burn up. that being said, I don't hear of a lot of faults causing transformers to fail.
usually what causes failure is the paper insulation breaking down over time. micro arcs in the oil tends to form acetylene gas, so if you see elevated gas compounds in an oil sample, you know it is time to replace or shut down the bank.
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08-31-2015, 03:38 PM
Boost Pope
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I keep looking at the secondary current rating. 22,834 amps. And I think to myself "Is the 4 at the end really necessary? Couldn't they have just rounded it off? Currents measured in the single digits seem like measurement noise when you're taking about power levels expressed in MVA. What would happen if you ran 22,835 amps through the thing? And, for that matter, how on earth did they arrive at that figure in the first place?"
Would you really expect all that oil to remain in liquid form in the event of a catastrophic failure?
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08-31-2015, 04:29 PM
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<p>Joe, look at the 345,000 V tap on the primary. 880MVA power delivery. Current, by definition on 3-phase is 880,000,000 / 345,000 / sqrt3. This gives the 1472.7, rounded up to 1473. It's the math that yields the funny numbers.</p><p>I can't answer the question about why not rounding, exept someone will do the math and say.. "wait a minute, you said this was a 880MVA unit."</p><p>Typically, the paper only creates a physical space and a minimum of structure. The oil does the dielectric work. The oil is tested and changed or filtered as needed (on a de-energized unit in my experience). Though, it is true that the degredation of the paper makes it weaker such that impulses can cause conductors to move, lowering the dielectric. That is why most poletop distribution XFMR's fail during inclement weather condtions (thunderstorms).</p><p>Higher currents mean higher temperatures, which does shorten life. It's all analog.</p><p>For general presentation:</p><p>http://www.feca.com/HDS_BASIC.pdf</p><p> </p>
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08-31-2015, 04:44 PM
Boost Pope
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<p>Joe, look at the 345,000 V tap on the primary. 880MVA power delivery. Current, by definition on 3-phase is 880,000,000 / 345,000 / sqrt3. This gives the 1472.7, rounded up to 1473. It's the math that yields the funny numbers.</p><p>I can't answer the question about why not rounding, exept someone will do the math and say.. "wait a minute, you said this was a 880MVA unit."</p><p>Typically, the paper only creates a physical space and a minimum of structure. The oil does the dielectric work. The oil is tested and changed or filtered as needed (on a de-energized unit in my experience). Though, it is true that the degredation of the paper makes it weaker such that impulses can cause conductors to move, lowering the dielectric. That is why most poletop distribution XFMR's fail during inclement weather condtions (thunderstorms).</p><p>Higher currents mean higher temperatures, which does shorten life. It's all analog.</p><p>For general presentation:</p><p>http://www.feca.com/HDS_BASIC.pdf</p><p> </p>
By the same token, however, I am offended by numbers which are arbitrarily rounded off in digital systems to values which do not obviously coincide with an even multiple of whatever integer they are based upon. So if a piece of software allows you to put exactly 1,000 entries into a form, I immediately think "Why a thousand? Why not 1,023?"
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08-31-2015, 04:55 PM
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<p>And that I fully understand. Here at work, we have people presenting numbers for comparison that differ by 0.5, for instance, but they present them to the nearest 0.01, which only serves to make the evaluation take more time and effort:</p><p>3.51, 3.25, 4.01, instead of 3.5, 3.3, 4.0</p><p>I don't care how many digits the DVM shows. How many are significant (in the scientific sense) or meaningful (in the sensibilty sense)?</p>
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08-31-2015, 05:07 PM
Boost Pope
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<p>And that I fully understand. Here at work, we have people presenting numbers for comparison that differ by 0.5, for instance, but they present them to the nearest 0.01, which only serves to make the evaluation take more time and effort:</p><p>3.51, 3.25, 4.01, instead of 3.5, 3.3, 4.0</p><p>I don't care how many digits the DVM shows. How many are significant (in the scientific sense) or meaningful (in the sensibilty sense)?</p>
When I first started working at Harris (which, at the time, manufactured large audio mixing consoles), the mechanical design was all done on paper, buy an old guy who had spent 20+ years in a metal fab shop and knew how **** worked in the real world.
A few years in, we got a new guy who was a SolidWorks whiz. He wasn't a young kid by any stretch, but came from an automotive background. And he had a habit of not merely specifying dimensions and tolerances to .00x, but also designing the products such that if two adjacent modules exceeded their width tolerance by more than a few thou, they wouldn't physically fit into the chassis.
He could never get it through his head that these parts were being manufactured on 50 year old brake ten feet wide which could have probably folded a Ford F-350 in half, but wasn't especially good at maintaining tolerances to five decimal places.
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08-31-2015, 11:45 PM
YOU LEAVE MY STICKERS OUT OF THIS, MOAR LLAMATHRUSTS
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09-01-2015, 10:44 AM
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