|
So Doble bought ENOSERV.
|
#
?
Jan 29, 2015 17:21
|
|
|
|
| # ? May 10, 2024 03:43 |
|
|
Not as exciting as the fuse operating, but I still think it's pretty interesting. Short-circuit withstand test on a 15 kV single-phase hookstick-operable disconnect switch. The fault current is 25 kA symmetric, the shot was taken with the appropriate X/R and closing angle to give a full asymmetric offset of ~52 kA peak. The current comes in through the top of the switch, out the bottom, across some bus (not shown), and then back up through the bus on the right. The current in the switch and in the bus are spatially in parallel, so they will create a force on another, because the current is in the opposite direction in the two conductors, the force will cause them to repel. The bus is solid 2" aluminum that is heavily braced, so it doesn't even appear to move. The best article I could find after a short Google search for asymmetric current. In the picture near the top of the article, the example current has a "major loop" for the first loop (initial start or current to subsequent zero crossing), meaning that the current has it's highest peak value in that loop. The next loop is a "minor loop" meaning the peak is less then the symmetric peak. The current waveform in the picture more or less matches that in my GIF. Because the force is proportional to the current squared, the peak force in the major loop is significantly higher than in the minor loop. So in the video you see the switch move a lot and take a set (major loop), and then you see it move a little bit again (minor loop). The whole test last for one second, but it stopped it after the first cycle, since the largest force is in the first loop.  The switch feels very solid when operating, so I think it is neat to see it look so flexible at high speed when hit with high forces. It also means that when there is a fault on the system, every thing that carries the fault current (every conductor between the source generators and the fault) all experience forces due to the current (both between adjacent conductors and internal to the equipment). This means that every time a recloser operates on a permanent fault, not only is a banging the fault over and over, it is subjecting all the equipment to high forces.
|
|
#
?
Jan 31, 2015 00:09
|
|
|
Awesome, and thanks for the detailed explanation!
|
|
#
?
Jan 31, 2015 03:48
|
|
|
That's pretty wild. I've seen faults on wire, where it whips around everywhere, wouldn't have expected an m3 switch to warp like that.
|
|
#
?
Jan 31, 2015 14:35
|
|
|
Noctone posted:If you run into more issues I might be able to help by taking a look at our RTS routine for the 311L. Don't have a routine for the 90L, unfortunately. I take it you work for Enoserv?
|
|
#
?
Mar 18, 2015 17:30
|
|
|
Nah, field engineer for a testing company. We mostly use RTS for relay testing.
|
|
#
?
Mar 18, 2015 18:14
|
|
|
Anyone ever see switches like these? It almost looks like the top button is just a rest, with the hammer being used to latch the bottom pb. Or are the buttons just that deteriorated... Richmond Power Station, closed since the '80s. ThinkFear fucked around with this message at 04:28 on Mar 24, 2015 |
|
#
?
Mar 24, 2015 04:24
|
|
|
Noticed this above the power meter for where I work today. Is it required to actually post this? Or is it a local code thing? The engraved part actually lists the wrong suite listed, but it was attached to the disconnect for the suite I work in (and we're by far the largest consumer of power in the building, being a restaurant with multiple HVAC RTUs, walk in coolers, etc, while the rest of the building is typical small strip mall stuff - donut shop, hairdresser, etc).  I've never seen anything like that posted in a small commercial setting before, so I was a bit surprised to see it. The nerd in me liked seeing it, the  part of me nearly poo poo myself when I saw the available fault current.(also  at "fase")
randomidiot fucked around with this message at 07:32 on Mar 24, 2015 |
|
#
?
Mar 24, 2015 07:27
|
|
|
I spend my days at work standing on a stainless oil catch pan and grate decking that's two feet from the back of some switchgear which is bigger than my kitchen. Am I likely to be exploded horribly?
|
|
#
?
Mar 24, 2015 09:04
|
|
|
Shim Howard posted:I spend my days at work standing on a stainless oil catch pan and grate decking that's two feet from the back of some switchgear which is bigger than my kitchen. Am I likely to be exploded horribly? If its a metal clad switchgear you're OK, if not you better stay further away. Do you have any idea what voltage its running?
|
|
#
?
Mar 24, 2015 10:06
|
|
|
TheFargate posted:If its a metal clad switchgear you're OK, if not you better stay further away. Do you have any idea what voltage its running? I finally walked around the other side and looked at the nameplate today, it's a 1MVA 4160>540 transformer.
|
|
#
?
Apr 10, 2015 01:42
|
|
|
Shim Howard posted:I finally walked around the other side and looked at the nameplate today, it's a 1MVA 4160>540 transformer. Definitely wouldn't get too close to any exposed bits. If its all enclosed you're fine. Its when you open up metal clad switchgears that it gets pretty hairy. Depending on the setup at least. I'm doing upgrades to 10 circuit 13kv switchgear and it can be a little nerve racking being a few feet away from 13kv bus, even though there's a divider. Stay away from exposed bits and you'll be fine.
|
|
#
?
Apr 10, 2015 02:15
|
|
|
Siemens claims to have crammed a 350HP electric motor into a 100 lb package. http://www.siemens.com/press/en/feature/2015/corporate/2015-03-electromotor.php
|
|
#
?
Apr 29, 2015 17:21
|
|
|
Shim Howard posted:Siemens claims to have crammed a 350HP electric motor into a 100 lb package. If I did my math right that's 732 lb-ft of torque at the 2500 RPM peak power point. Mid-300s HP and mid-700s torque at mid-2000s RPM sounds a lot like the 7.2L Caterpillar diesel my parents' old RV had. That weighed in at around 1250 lbs dry though and took gallons of fluids so I'd bet it's closer to 1400 in operation. Now that's got me thinking about the feasibility of an electric RV. Lots of space for batteries, that's for sure, and every major park has 50 amp service to charge from. edit: heh, range extender for such a setup: http://power.cummins.com/onanpowerWeb/navigation.do?pageId=1225&parentId=533 wolrah fucked around with this message at 18:36 on Apr 29, 2015 |
|
#
?
Apr 29, 2015 18:02
|
|
|
A lineman was killed today in Texas, working to restore power after a storm. Unofficial reports in the lineman community say it was backfeed from an illegally connected consumer generator.quote:A lineman working to restore power in Tyler County was electrocuted. http://www.12newsnow.com/story/28933066/lineman-killed-while-working-to-restore-power-in-tyler-county
|
|
#
?
Apr 30, 2015 02:08
|
|
|
wolrah posted:If I did my math right that's 732 lb-ft of torque at the 2500 RPM peak power point. At that level of torque and power/weight, with a flywheel for energy storage, you're in electric dragster territory.
|
|
#
?
Apr 30, 2015 17:38
|
|
|
So, I'm sure everyone and anyone associated with the energy industry is chattering about the Powerwall batteries that Tesla just unveiled. I think everyone saw it coming, but I'm kind of shocked at the low price point. My question is, are they actually viable as an alternative to traditional, central-source power systems? As someone who just started an MS in power engineering, I find the prospect of one of those in every home (and especially implementation in emerging markets) to be a definite threat to my job security in the long term...
|
|
#
?
May 1, 2015 13:05
|
|
|
I have a few thoughts. -I'm wary of having a couple very large fire hazards in my basement. -It's not fundamentally different from having a small (2kW) generator. -They are cheaper than having a huge rack of deep-cycle UPS batteries like you have in industry. So there may be novel usage that could drive this appliance to be the next "water heater" in the sense that you have to have one in a house to sell it. -It makes me think of those roof-mounted water heater tubes that are great if you have an extra 10k to invest in a house, but aren't going to replace a water heater.
|
|
#
?
May 1, 2015 14:47
|
|
|
They are also "inverter sold separately" - it is literally just the storage. The way it's worded it sounds like you can do either solar *or* grid tie, but not both. Has anyone seen a clarification on that? Did I misread the release? It would be awesome to be able to do both, top up on off-peak rates overnight, and drain during the day with whatever baseline your panels provide.
|
|
#
?
May 3, 2015 20:52
|
|
|
This seems like the right place to ask, so: I have a laser capacitor. It's 6 capacitors in a welded steel case, sharing a common ground terminal; each one is 225 uf and is rated for 1.5 kv. The capacitor datasheet says it's rated for 4 kiloamps discharge, and 20% voltage reversal. Working it out, a 250 us pulse would be the fastest I could discharge the thing into something without exceeding the current rating. I have the dozen IR 50RIA120 SCRs that came with the cap, but they're only rated for 1200v and are thus lame as hell. Is there a good high-power book I can read that would tell me:
thanks atomicthumbs fucked around with this message at 19:14 on May 12, 2015 |
|
#
?
May 12, 2015 06:15
|
|
|
atomicthumbs posted:words I have no idea what you are saying here but I want to hang out with you.
|
|
#
?
May 12, 2015 13:47
|
|
|
atomicthumbs posted:This seems like the right place to ask, so: I would suggest finding the oldest electrical engineer (preferably a WWII or Korean War vet) at the best nearby university and asking him these questions.
|
|
#
?
May 12, 2015 18:45
|
|
|
I used to work at GA as a technical sales engineer in the capacitor group. Where did you get the cap and what are you using it for?
|
|
#
?
May 12, 2015 23:13
|
|
|
SeaBass posted:I used to work at GA as a technical sales engineer in the capacitor group. I took apart a flashlamp-pumped Nd:YAG medical laser (a New Star Lasers Cooltouch II) that was due for recycling and I'm using it for destruction
|
|
#
?
May 13, 2015 00:06
|
|
|
atomicthumbs posted:I took apart a flashlamp-pumped Nd:YAG medical laser (a New Star Lasers Cooltouch II) that was due for recycling and I'm using it for destruction I knew that cap looked familiar. Sorry, can't help you.
|
|
#
?
May 13, 2015 05:19
|
|
|
atomicthumbs posted:This seems like the right place to ask, so: Start out by using the trigger/switching circuitry off the laser you took this out of, as well as the charging circuitry, if possible. I'm assuming the laser is xenon tube pumped however, so the output of the cap bank probably just went right to the anode and cathode of the xenon strobe, with a multi kilovolt trigger transformer ionizing the tube gases externally to trigger it, so there may really be no switching circuitry to pillage I guess. As for actually designing one, I can't help you there, it's been too many years and I tend to shy away from that kind of stuff and leave it for more specialized analog/power engineers to worry about. e: the SCRs I'm guessing were actually from an active rectifier bridge, probably a 3 phase one, used to charge the capacitor bank. For switching you could consider something like krytrons (haha, good luck, they're considered a critical part of a nuclear weapon initiator) or a variety of other gas discharge tubes. They tend to be capable of switching extremely high currents economically since they're mostly obsolete, at least compared to kilovolt-plus, kiloamp-plus SCRs, IGBTs, MOSFETs, and similar devices. Here is a great article on GDTs - http://www.electricstuff.co.uk/pulse.html Note that they consider 3kA and 5kV "medium" power levels for krytrons. That is a pretty good sign that a device that will do the job is somewhere in this category. kastein fucked around with this message at 05:41 on May 13, 2015 |
|
#
?
May 13, 2015 05:35
|
|
|
kastein posted:Start out by using the trigger/switching circuitry off the laser you took this out of, as well as the charging circuitry, if possible. Unfortunately the SCRs were the switching setup; they were set up two to each capacitor, with the whole shebang attached to a controller board (not shown):  They're only rated for 1.3kv surge each, so I won't be able to get the full 6-megawatt pulse this thing is capable of (unless I'm misinterpreting how it's laid out). Solid state is lame anyway  The charge power came from a 1.5kv capacitor charger power supply (quite handy) attached to that board on the capacitor, which handles both charging and bleeding duties (also handy). The flashlamp itself was connected in a manner I can't quite remember to another board, which has a pair of lower-voltage but still pretty big electrolytic capacitors attached to it, as well as a "simmer converter" box which apparently outputs 1200v at low current to keep the tube ionized. I'm guessing it's a 3-stage simmer > trigger > FLASH triggering process. There was a huge honking 25-pound toroidial transformer mounted to the bottom of the laser casing, which I discovered was actually very boring when I removed its mounting ring and found out it was a 115-to-115v isolation transformer with a secondary winding that output 24v. Thanks for the article; looks like I've got some reading to do. (I've got some thyratrons in a bag I should probably look at, but they're mostly lame low-voltage stuff.) It looks like hydrogen thyratrons and ignitrons don't cost too much on eBay, but the latter is mostly meant for switching continuous high-amperage currents. e:  
atomicthumbs fucked around with this message at 07:10 on May 13, 2015 |
|
#
?
May 13, 2015 06:09
|
|
|
 I came across this substation control panel while in the field last week.
|
|
#
?
May 23, 2015 04:11
|
|
|
I really hope that just means the equipment was retired.
|
|
#
?
May 23, 2015 04:18
|
|
|
freezepops posted:
We have a bunch of similar panels at work. Generally thats what they end up looking like after we replace the electro mechanical relays with micro processor ones.
|
|
#
?
May 26, 2015 11:41
|
|
|
I'm confused. Did something blow up in there, or did someone just decide to paint a cock on the door?
|
|
#
?
May 26, 2015 13:44
|
|
|
Those are some ugly patch jobs to those panels.
|
|
#
?
May 29, 2015 22:08
|
|
|
TheFargate posted:We have a bunch of similar panels at work. Generally thats what they end up looking like after we replace the electro mechanical relays with micro processor ones. Same in all the substations I work in. Although sometimes they get fancy and use a grinder to make swirls on the patch panels to add a bit of pop.
|
|
#
?
May 30, 2015 18:15
|
|
|
KillHour posted:I'm confused. Did something blow up in there, or did someone just decide to paint a cock on the door? Some electromechanical relays were replaced and the patched area was painted over. The  shape I can't explain.
|
|
#
?
May 30, 2015 19:11
|
|
|
freezepops posted:Some electromechanical relays were replaced and the patched area was painted over. The Dude was probably bored. You should see some of the stuff on our feeder rows. It ranges from dick shapes to straight up art. We usually just paint the patches to match the existing stuff.
|
|
#
?
May 31, 2015 03:47
|
|
|
This is what happens when copper thieves cut loose the Source Load (neutral/ground) from a set of in service voltage regulators in a distribution substation. The equipment is electrically floating and it turns concrete into glass trying to find ground.  You can see in the above picture that the max/min history hands on the step indicator dial show that this unit boosted all the way +16 and bucked almost maximum as well, hunting around trying to reach its setpoint with no neutral for the load it was carrying. All three units had the same situation, electrically, I assume this one was carrying the most load, or at least it was after the circuit lost its ability to carry the unbalanced load. The other units only glass streaks outlining where they sat. The thieves escaped unharmed somehow, but have been caught. To get a slap on the wrist or whatever, they generally get minimum punishment.
|
|
#
?
Jun 2, 2015 00:16
|
|
|
Just had a 4kv transfer bus explode about 20ft away from me! That was pretty cool. Wasn't carrying any load though so it wasn't too impressive.
|
|
#
?
Jun 3, 2015 16:09
|
|
|
For the electricity pros, here's a shower thought that's been bouncing around my head this morning: If you were in charge of building a new grid from the ground up where for whatever reason compatibility with existing devices wasn't an issue in any way, what would you do differently as far as the power that gets delivered to end users? I assume a higher voltage than 120 at the every day ordinary outlet is a given, but is 240 a good choice or might it be better to go higher if one's completely abandoning compatibility? At what point does the added danger of the higher voltage outweigh the increased capacity on a given conductor? Do we hit that point before the voltages get high enough that adapting them down to levels required by electronic devices starts to get complicated? Facebook's delivering 277vAC to the servers in their new datacenters presumably because it's higher than 240 but still readily available from the commercial grid. Might a higher or lower standard frequency be useful? This one I'm really interested in since it seems like it could go either way from the little I know. Big motors seem to like lower frequencies and they don't have as much impedance to deal with for longer lines, but higher frequencies are better for lighting or high RPM motor applications and require smaller transformers. I'm pretty sure it's easier to convert higher frequencies to clean DC as well with traditional power supply, but I'm not sure if it really matters to switching supplies which are more common these days. Does DC have a place in the middle ground between 12/24/48v automotive/telco and long distance HVDC runs? I kind of straddle the line between telco and IT as part of my job and even in telco where -48vDC is the standard it seems like that only lives on because it makes it easy to just slap a bunch of batteries in a remote central office to provide backup power.
|
|
#
?
Jun 7, 2015 19:09
|
|
|
angryrobots posted:The thieves escaped unharmed somehow, but have been caught. To get a slap on the wrist or whatever, they generally get minimum punishment. Good that they got caught, but I feel bad for the cops that picked them up. I mean, I would have dumped a week's worth of poo poo into my pants had I cut a wire and THAT happened. They're gonna have to burn whatever vehicle they picked them up in. My question is, what happens to everything downstream when some idiot does that? Is there sufficient protection to prevent something like that from affecting utility customers beyond a brownout/blackout? Or do they get a  lesson about how important surge protection is?
|
|
#
?
Jun 10, 2015 07:02
|
|
|
|
| # ? May 10, 2024 03:43 |
|
|
some texas redneck posted:Good that they got caught, but I feel bad for the cops that picked them up. Depends on the voltage/company. Our 13kv systems will automatically switch to another feed but we also dont use voltage regulators of that type. Our 4kv system uses a similar style but its a radial feed, so once something like that happens, youre screwed until someone manually cuts the circuit over to another feed.
|
|
#
?
Jun 10, 2015 11:43
|
|