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Hope Three-Phase doesn't mind me jumping in...I am a substation operator and I have what everyone loves to see...PICTURES! Here is a 345KV circuit breaker built in the 1960s, and later modified. The Contacts are in the football looking section at the top. The 2 columns on either side which lead to those round tanks contain Current Transformers which monitor, you guessed it, current. It is a SF6 filled breaker, something Three-Phase touched upon earlier. The SF6 gas is the insulating medium.  Compare that breaker to a modern 345KV breaker:  This is the Hitachi HVB. Much more compact and less complicated. Here is a Transformer which is dropping 345KV to TWO 138KV feeders.  Here is a 27KV circuit breaker that failed:  That breaker uses a vacuum to interrupt the arc. What happened was, this breaker was used for Capacitor Bank switching and apparently could not handle the incredible inrush of current. One of the contacts literally welded itself together. The indication showed OPEN and as it was being racked into connect, there was an arc because of the welded closed contact. BOOM. No one was hurt. Remember:  Bonus: 
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Sep 4, 2011 19:49
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Crackpipe posted:What parts of these would be safe to bump into? I've always viewed substations as death mazes where bumping into absolutely anything will kill you instantly. Three-Phase answered this question very well, but another general rule of thumb, although NOT always true, is if you need to step up to touch something, it is NOT SAFE. Usually BUT NOT ALWAYS, everything ground level which you can touch is safe to do so. Energized, uninsulated equipment is suspended high above with the use of insulators, and if it is ground level, it is usually enclosed in fencing. Like Three-Phase said though, the real danger is if you accidentally are carrying something like a ladder or pipe. You must ALWAYS be aware of your clearances between you, any item you are holding, and the energized bus work. quote:SEXY. How many MVA is that? 500? 1000? Actually it is only 327 MVA, believe it or not. ----------------- So I am sure many people wonder when a cable fails in an underground electrical system, how do they find where the damage is? Well here goes..a little background first. In my utility distribution voltages range from 27KV,13.8KV and 4KV. I deal with 27KV. The switchgear is made up of cubicles which look like this when no circuit breaker is in connect:  The 2 red shudders are where the circuit breaker stabs:  connect. The shudders open as the circuit breaker is racked into connect. The top stabs make up with the energized station bus and the bottoms stabs connect to the potheads which are connected to the cables(called Feeders) which go out to the street and will eventually have the voltage stepped down again before it enters your house. Once the breaker is closed, a complete path is made, from the energized station to the feeder. Okay so now back to the scenario I first mentioned. There is a fault somewhere on a feeder. The relays associated with the feeder see a huge spike in current and trip the circuit breaker open. Now the cable is mostly underground and the fault can be anywhere. What we substation operators do, as directed from the energy control center is to "establish a condition". What this means is we put high voltage onto the feeder and it acts as tracing current which goes straight to the damage on the cable. This is done by removing the circuit breaker from the cubicle and inserting a Ground Breaker or a Ground & Test Device. This "breaker" only has stabs which connect to the cable going to the street, it does not have any stabs to connect to the energized station bus. This is the High Voltage Test Set:  It is used to establish a condition (what I am currently describing) and it is also used to test the insulation of feeder cables after repairs are made, to ensure that there are no other faults on the cable. It attaches to the feeder through the ground breaker & test device like so:  (also note the lock out & tag out procedure, Three-Phase mentioned earlier a key interlock system which is hard to see in this photo, but it is there) The black cable is connected to the feeder through the test device it is in, and is connected to the high voltage test set. We turn on the high voltage test set which raises voltage onto the cables until it reaches the fault where the voltage drops off and a huge spike in current occurs. Now crews who are trained in fault locating, go out in trucks with a map of the feeder run in hand and this is what they do; They will usually start in the middle of the feeder run, and go into the manhole where the cable is and place this device, a galvanometer onto the cable:  The red portion is placed onto the cable and the spike in current which I described earlier is read on the meter. If they read that spike, that means the feeder cable is good up until that point. The crew will then go to the next manhole down the line and do the same thing, but now if they do not read any current on the galvanometer, they know the fault is between the last manhole where they read current, and the manhole they are now in. We in the substation then shut down the high voltage test set, and apply a ground via the ground breaker. When the ground breaker is closed, instead of making a complete path from the energized station to the feeder, it makes a path from the station ground grid to the feeder, making it safe for crews to do their repairs. Once the repairs are made, we hook up the high voltage test set again, and this time, raise voltage for a specific amount of time to ensure the feeder cable has been repaired correctly and no other damage has been done. If it is damaged, we will not be able to raise and sustain voltage. We start the process all over again by establishing a condition to find where the other damage is. When we establish a condition however, it is not always required for field crews to open every manhole and read the current via the galvanometer, the reason being, this is what Establishing a Condition often sounds like; http://smg.photobucket.com/albums/v323/somekidfromny/?action=view¤t=0513001048.mp4 The crews will just drive the route of the feeder until they hear that sound coming from a manhole, or we will have customers calling us saying they are hearing something "exploding" from a manhole. That crack is the sound of the current arcing to ground, ie: the fault on the cable grounding out to something in the manhole. That's it for now! Some Guy From NY fucked around with this message at 12:11 on Sep 5, 2011 |
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Sep 5, 2011 12:04
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Just did a 16 hour shift holding our breath while we almost broke our all time peak MW usage. Our record was 13,189 MW's set in july 2011 - today we hit 13,161 MW. We lost surprising few distribution feeders. The night is still young though and we still have 3 more days of high 90 degree weather with humidity. I am glad I am now off until Sunday night. woo! here is a picture just for picture's sake:  ABB 138KV breaker. Some Guy From NY fucked around with this message at 03:37 on Jul 19, 2013 |
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Jul 19, 2013 03:13
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Noctone posted:Over the next three days my crew and I have to test 35 runs of 25kV cable (i.e. 105 individual cables) and 11 25kV S&C fused air switches. Ha, I have people do that all the time to me. I will be infront of a high voltage test set performing a high-pot, with the cable going to the G&T device with everything roped off with danger tape and signs...and guys will still go around/under the tape, step OVER the cable which is putting out 25KV to come ask me if "I'm busy". and these are career substation workers.    Some Guy From NY fucked around with this message at 04:10 on Jul 19, 2013 |
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Jul 19, 2013 04:02
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Hmmm that is interesting to hear about the ABB breakers failing. We have dozens and dozens on the system, including my home substation. We have not had any issues with these breakers anywhere in our company as far as I know, except for one defective one where the pressure relief valve was installed literally backwards from the factory and it blew up. Other than that we are continuing to replace older breakers with them. Mad scientist breakers activate! (modified 345KV SFA breakers)   Here is the original:  This was an air insulated, air open/ air close 345KV breaker from what I was told. This one in the picture was the last one in service in our system before being replaced (as seen in the pic) 5 years ago. It has THREE interrupters per phase, opposed to the "newer" modified version with just 1 interrupter in the football shaped head. The 2 huge columns on either side contain CT's in the round tanks at the bottom. Some Guy From NY fucked around with this message at 23:10 on Jul 19, 2013 |
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Jul 19, 2013 23:07
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image dump!   
Some Guy From NY fucked around with this message at 17:08 on Dec 21, 2013 |
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Dec 21, 2013 17:04
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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.
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May 30, 2015 18:15
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