How does a substation work?

hey guys you are watching Bob's decline I have had quite a few requests to make some more videos about substations and how they work so what we're gonna do here today I'm gonna give you a real quick rundown of how a substation works now we're just going to be covering the basics here we got here guys we have two separate transmission lines coming into the substation here now these are both 138 thousand volt lines two lines coming in beating to power transformers so what happens the line comes in goes into these switches first thing you can see it stops up on top on the steel girder there the only reason the wire keeps going if it carries on overhead to that tower off the distance and then again to eventually another substation one hundred thirty-eight thousand volt line comes down in through this switch now this disconnect switch which isolates the substation from the high voltage line can only be operated under no-load conditions if you open that switch right now it would draw an arc even until it's fully open it'd be extremely dangerous not only to the personnel but it would it would most likely cause damage to the equipment so we come on through these leads into our bus work now the reason we go from the switch to bus work is we have a tie this tie switch is open because we have two independent feeds for each transformer if there happens to be a fault on this High Line we would lose power to half the pound here we can open this switch to isolate the transformer close our tie switch which essentially is stealing power from this High Line in order to feed the other transformer pretty simple setup mind you the process is much more complicated and time-consuming now I mentioned earlier both that disconnect switch that it can't be operated under load so how do we shed the load in order to operate that switch so to drop the load we have a second disconnect switch this one is actually called a circuit breaker now there's two switching devices on this breaker this one here is your visual switch which opens much the same as these other guys here but we have this second insulator here which is actually a hollow tube filled with sulfur hexafluoride gas sf6 gas now the reason it's filled with that gas is it's an extremely heavy gas it's much more dense than oxygen or nitrogen so as the device disconnects inside that tube the arc will begin to form the heavy air inside they will actually snuff out the arc and then the blade opens to give us a visual disconnection with us that this has actually disconnected itself from the line looking down below we have some grounding bursts again part of this switching device those will close up onto these leads right here and drain any induction in these lines underground to make things safe to work on again this is just the very basics of this setup there are some extremely complicated procedures to this so don't use this video as a training video it is more just for curiosity on the basics on how the system works so after our circuit switcher were coming into our power transformer now like most transformers these fellows are filled with oil they're just a much larger version of what you see on a pole now much like a car the oil is used for cooling as the transformer gets more and more loaded it will heat up and the oil which travels through these Reed eaters it's cooled off we also have an expansion tank up here conservator tank what you see right here are lightning arresters they're an actual physical path from the high-voltage line to ground basically when the voltage gets too high this allows it to bleed out and ground that's why their lightning arresters it mostly gets used during a lightning strike where the hundred thirty thousand volts goes into the transformer that's where the magic starts right there wire goes in through that bushing down into the transformer through all around a bunch of windings and then it comes out on this side onto these much smaller bushings now the reason these bushings are so much smaller is the voltage coming out is 7,200 volts approximately we can moded the transformer much the same ways that went in and the disconnects now we're pretty much gonna have the exact same stuff on the low-voltage side as the high voltage side but the opposite we have our disconnect switches close to the transformer here and our actual load braking devices are gonna be on the circus themselves as they go out into the town one by one this particular substation has six separate circuits now you'll see the wires go from our load braking device underground and up into a distribution circuit now this particular device is actually called an oil reclosure there are many different types Louvre closures there's electronic ones back in there closures or / closures and this operates much like the sf6 gas interrupter except where it's a lower voltage it doesn't require the gas it just uses simply oil to snuff out the arc as the circuit trips this guy is hooked up to a computer sometimes again when your power flickers there could be a Fault in a line let's say right now a bird lands on that steel Texas beacon the high voltage the surge in current will actually trip out power in this device and the electronics will allow it to reclose to turn power back on immediately however if the fault current is - hi or if it remains a fault this device will lock the power out until alignment comes out on-site to investigate further another one of my videos hopefully you learned a little something today about substations now I know we only scratched the surface pretty much just covering how the power comes in and how it goes out if you are lineman or aspiring to be a lineman don't forget my videos are to be used as a guideline only always adhere to your company's policies and procedures don't forget to subscribe we'll see you next time

Channel: Bobsdecline - Lineman blogger

Views: 248,812

Rating: 4.7809525 out of 5

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Id: QC0t_9Z_9hg

Length: 6min 56sec (416 seconds)

Published: Thu Aug 22 2019