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Three-Phase, you always have such a wealth of terrifying and awesome knowledge to contribute to this thread. What's your area of experience? High-voltage electrician?
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Jan 28, 2018 00:00
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Well I mean it's right there in the name, anything three-phase is almost always happening at the kind of currents that, when they encounter the human body, produce results where the technical term is really just a nice way of saying 'chunk-style' edit to add: like that video with the guy cranking the breaker we've all seen where there's not much left but a steaming boot and a weird smell
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Jan 28, 2018 00:16
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SealHammer posted:Three-Phase, you always have such a wealth of terrifying and awesome knowledge to contribute to this thread. What's your area of experience? High-voltage electrician? I think he's said before he's "medium voltage" (or something like that). I'm not sure if the numbers have changed or not, but this is IEEE definition from a few years ago: LV < 600v MV 601v-69 Kv HV 69 Kv - 230 Kv EHV 230 Kv - 800 Kv UHV > 800 Kv
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Jan 28, 2018 00:17
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MrYenko posted:The scene in Tora Tora Tora where the P-40 crashes through the flight line while ground crew run to safety was supposed to have the P-40 in question crash at the END of the flight line, and not THROUGH it. The extras were ACTUALLY running for their lives. One of the Tomcats in Final Countdown sufferer a stall while mock-dogfighting the Zeros and almost crashed. Starts at 2:45 here. https://youtu.be/f3XNEWtJF0o
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Jan 28, 2018 00:25
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PopeCrunch posted:Well I mean it's right there in the name, anything three-phase is almost always happening at the kind of currents that, when they encounter the human body, produce results where the technical term is really just a nice way of saying 'chunk-style' A friend of mine who's a robotics engineer was working at an air compressor factory and got electrocuted by a three-phase 440v cable hanging down from the roof. He was assured that the section he was working on had been disconnected. Then he brushed against the cable and went "Ahh poo poo that had some copper wires hanging out the end and it scratched me. Hang on, why do I smell burning?". Turns out the cabinet that the cable went to had been traced incorrectly and another section of the factory that was due to be decommissioned the following week was disconnected instead. He tore up his contract on the spot and refused to go back to finish the work even when they offered to double his rate. He knows how loving close he came to being exploded.
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Jan 28, 2018 00:28
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There's nothing magical about 3 phase power, it's just 3 normal wires, but instead of going from active to neutral, you go from one active phase to another, and you end up with a higher potential V. 440V would definitely hurt, and have the potential to kill you if the current disrupted your heart rhythm or burnt some important flesh or organ, but it's not mechanically different to a 110V line.
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Jan 28, 2018 00:50
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Phanatic posted:One of the Tomcats in Final Countdown sufferer a stall while mock-dogfighting the Zeros and almost crashed. Holy poo poo that doesn't even look like a gently caress up until u know its an accidental stall
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Jan 28, 2018 01:58
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The SOP for "got sent back in time and now I have to fight propeller aircraft in a jet" is probably just flying close enough to them that your wake remodels their shitholes.
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Jan 28, 2018 02:12
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And then landing somewhere and not being able to take off because spare parts aren't a thing and modern jets need shitloads of maintenance.
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Jan 28, 2018 02:15
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Volcott posted:The SOP for "got sent back in time and now I have to fight propeller aircraft in a jet" is probably just flying close enough to them that your wake remodels their shitholes. or just ignore them since they can't touch you anyway
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Jan 28, 2018 02:24
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Three-Phase posted:To me this is the industrial cabinet/operator/indicator label higherarchy: As soon as the supreme court allows it I'm getting married to laser engraved snap-in terminal block markers
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Jan 28, 2018 02:59
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Fallows posted:Holy poo poo that doesn't even look like a gently caress up until u know its an accidental stall Holy poo poo indeed!
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Jan 28, 2018 03:33
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Fallows posted:Holy poo poo that doesn't even look like a gently caress up until u know its an accidental stall Holy actual gently caress that looks like he pulled out of that stall only MAYBE 100 feet off the deck?! 
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Jan 28, 2018 03:50
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Jan 28, 2018 07:39
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I was expecting worse honestly.
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Jan 28, 2018 07:50
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It would have been much worse if he didn't grab that vent.
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Jan 28, 2018 07:55
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Gaius Marius posted:I was expecting worse honestly. Well, he's still turbo-hosed since he can't stay up there forever. Hopefully this was in a place where the person filming that isn't all "Not my business".
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Jan 28, 2018 08:30
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starkebn posted:There's nothing magical about 3 phase power, it's just 3 normal wires, but instead of going from active to neutral, you go from one active phase to another, and you end up with a higher potential V. 440V would definitely hurt, and have the potential to kill you if the current disrupted your heart rhythm or burnt some important flesh or organ, but it's not mechanically different to a 110V line. Sure, but the vast majority of circuits you'll encounter on a 110v line are 10 amp - still enough to kill you fifty times over in ideal circumstances, sure, but there's a few moments where rescue is possible. If you're dealing with 3ø circuits, the available amperage - and amps are what kills you - range from what, 20? to well into "well, at least nobody had to splash out for cremation" territory.
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Jan 28, 2018 10:05
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Fuckin double post.
PopeCrunch fucked around with this message at 10:23 on Jan 28, 2018 |
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Jan 28, 2018 10:18
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eh, I've met people who've been hit by 50kV and survived, it all depends  I'm sure he wouldn't recommend it to others though. All I'm trying to point out is that '3-phase' power isn't some sort of extra-killy electricity that some people here seem to think.
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Jan 28, 2018 10:52
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PopeCrunch posted:Sure, but the vast majority of circuits you'll encounter on a 110v line are 10 amp - still enough to kill you fifty times over in ideal circumstances, sure, but there's a few moments where rescue is possible. If you're dealing with 3ø circuits, the available amperage - and amps are what kills you - range from what, 20? to well into "well, at least nobody had to splash out for cremation" territory. If you come into direct contact with a 110v cable it does not matter what the amps are because it is your body's resistance that determines the current through your body. A 20 amp hookup won't kill you twice as dead as a 10 amp one.
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Jan 28, 2018 11:07
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This is basic ohms law poo poo. It does not matter how much amps the power supply can deliver (as long as it's enough), it's the voltage of th supply and the resistance of the load that determines the current through the circuit. A human body with a (total) skin resistance of 100k grabbing a 110v line will have a current of 1.1mA running through it, irregardless of the line being 10A, 20A or 2A.
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Jan 28, 2018 11:19
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One more: Three phase supplies are more dangerous because the voltage between two phases is higher than between a single phase and neutral (208v vs 120v in US) and thus will deliver more current into your dumb rear end
spankmeister fucked around with this message at 11:37 on Jan 28, 2018 |
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Jan 28, 2018 11:31
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Wasabi the J posted:Holy actual gently caress that looks like he pulled out of that stall only MAYBE 100 feet off the deck?! Nah, just camera perspective. He went into the climb already stalling and the slight turn made it into a wing drop stall you can see when it snaps left. He didn't have enough authority to level the plane so he let it continue rolling to nose down, inverted nose down is still nose down. Probably lost 4-600 ft flying 3000+. For perspective a C-172 should for the worse pilots at most recover after losing 100ft.
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Jan 28, 2018 12:20
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spankmeister posted:One more: Three phase supplies are more dangerous because the voltage between two phases is higher than between a single phase and neutral (208v vs 120v in US) and thus will deliver more current into your dumb rear end Yes, if you touch phase to phase. If you just grab one wire of  3 phase electricity and it earths through you, then you're just getting 110v in the US. I can tell you already know that, just clearing it up for the listeners.
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Jan 28, 2018 13:00
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After heart surgery, I was left with a pair of leads exiting my body just under my ribcage so the docs could nuke my heart if it started doing the wrong dance. When a doc came into my room to remove the leads, I sort of laughed and said, "Hey, so a 9V battery could take me out right now, huh?", and he replied in complete deadpan, "Yes. Let's not do that." BTW, when he removed them, the term "heart strings" came to mind because I could feel the whole drat process. Ew.
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Jan 28, 2018 13:17
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Alls I know as a moderate home improver, is that I just straight don't gently caress with electricity. I've been zapped into near incontinence by a wide variety of voltages/amperages, and it has taught me that I don't belong anywhere near electricity unless it involves changing a battery in a remote.
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Jan 28, 2018 13:20
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SealHammer posted:Three-Phase, you always have such a wealth of terrifying and awesome knowledge to contribute to this thread. What's your area of experience? High-voltage electrician? Electrical engineer but I deal a lot with low and medium voltage equipment. (Switchgear, protection systems, control wiring, SCADA and motors.) shame on an IGA posted:As soon as the supreme court allows it I'm getting married to laser engraved snap-in terminal block markers We are using more high-quality terminal labels as well as uniquely colored terminals. Especially when you have a cabinet where there is a mix of 120VAC, 125VDC, and 24VDC, as well as 0-10V and 4-20mA analog signals for processes. spankmeister posted:One more: Three phase supplies are more dangerous because the voltage between two phases is higher than between a single phase and neutral (208v vs 120v in US) and thus will deliver more current into your dumb rear end High-leg (I’ve called it “center tapped”) delta can be dangerous too because one of the phases will have a higher phase-neutral voltage than the others. I’ve heard this called the high, wild, or bastard phase. https://en.m.wikipedia.org/wiki/High-leg_delta So two wires are 120V to neutral, the wild leg is 120 times the square toot of three - 208V, to neutral. Almost double the voltage. Three-Phase fucked around with this message at 14:08 on Jan 28, 2018 |
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Jan 28, 2018 14:04
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Three-Phase posted:We are using more high-quality terminal labels as well as uniquely colored terminals. Especially when you have a cabinet where there is a mix of 120VAC, 125VDC, and 24VDC, as well as 0-10V and 4-20mA analog signals for processes. Awwwww. Color coding is so cute.  That’s apparently a Lockheed product, but they’re all like that. If you need to ID a wire, you’d best have the diagram(s,) and hope the roll marks haven’t worn off. Ask me how long I’ve spent in E&E bays with a radio, trying to find a wire we think is broken or shorted... 
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Jan 28, 2018 14:32
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Any idea on which Lockheed product? I'm guessing one of their radar products for the market not already cornered by Raytheon or some fire control system. Edit: ALQ-157 maybe?
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Jan 28, 2018 14:45
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MrYenko posted:Awwwww. Color coding is so cute. I've seen this a lot on surplus military equipment. Seems insane to me but what do I know.
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Jan 28, 2018 15:03
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What's the advantage/purpose of not color coding? It can't just be saving pennies on not having to stock different colors, right?
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Jan 28, 2018 15:37
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It happens in plumbing too  
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Jan 28, 2018 15:47
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deoju posted:What's the advantage/purpose of not color coding? It can't just be saving pennies on not having to stock different colors, right? I can think of the colors fading or colorblind technicians.
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Jan 28, 2018 15:55
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Phanatic posted:One of the Tomcats in Final Countdown sufferer a stall while mock-dogfighting the Zeros and almost crashed. The Zeros in that scene didn't serve in the war- but that wasn't their first flight or dogfight against US aircraft- they were originally built and flown in Tora Tora Tora.
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Jan 28, 2018 15:55
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deoju posted:What's the advantage/purpose of not color coding? It can't just be saving pennies on not having to stock different colors, right? Pretty sure it's exactly that.
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Jan 28, 2018 16:03
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Snowglobe of Doom posted:It happens in plumbing too I’m the kink in the dead-center of the photo screaming for an elbow. Now, that’s a shithole. PainterofCrap fucked around with this message at 19:40 on Jan 28, 2018 |
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Jan 28, 2018 16:18
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deoju posted:What's the advantage/purpose of not color coding? It can't just be saving pennies on not having to stock different colors, right? IME those wires are labeled
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Jan 28, 2018 16:23
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deoju posted:What's the advantage/purpose of not color coding? It can't just be saving pennies on not having to stock different colors, right? I believe the cables are numbered on the outside. Given the complexity of the systems, I can imagine that you'd soon run out of colours: 'So, the interior heater is a green/red striped wire and the make-bomb-go-boom system is an avocado/crimson stripe. Better not get them mixed up'
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Jan 28, 2018 18:58
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deoju posted:What's the advantage/purpose of not color coding? It can't just be saving pennies on not having to stock different colors, right? Logistics burden is a huge thing, so probably just the minimizing stock part is probably true. Wasabi the J posted:IME those wires are labeled Mine too, I spent many hours chasing problems in F-14 fire control and avionics systems.
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Jan 28, 2018 19:01
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