#641 – Power Transmission with Toby Robb

Dave Jones: This is the Amp Hour Podcast, released July 31st, 2023, episode number 641 with Toby Rock. Welcome to the Amp Hour. I'm Dave Jones from the EEV blog.

Chris Gammell: And my name's Toby Rob and I've been working in distribution power industry for around 14 years.

Dave Jones: Hey Toby, thanks for joining us mate. How are you Dave? Good, good, good to have a fellow Aussie on the Amp Hour again.

Chris Gammell: Yeah, I'm not too far south of you I think.

Dave Jones: No, no, where from exactly?

Chris Gammell: I'm just south of Wollongong there in Illawarra.

Dave Jones: So yes, power, something both Chris and I don't know, well power distribution and big power stuff, something Chris and I don't know about. We've had Paul Zaweda on the show before, he talked about the smart grid and all that sort of stuff. So I'll link it in. But you're more into like the transmission line stuff. So tell us what your day, what's a typical day for you?

Chris Gammell: Well, so I suppose in the last few years I've actually been sort of stuck behind a desk a bit more. But I'll probably try and talk about, you know, the sort of 10, 13 years before that. But I started with my company as an adult apprentice and basically became a linesman and what we call a fitter over here. It's basically just an electrician. But yeah, I work on the distribution network, which is basically poles and wires. So all those poles and all those wires that are out front of your house or maybe you've got some underground where you are.

Dave Jones: We're completely underground. I was going to ask about difference between underground and poles, but we'll go into that later, I think. Sure. Let's not just jump directly into that. Tell us, where does power come from and how the hell does it get to us? And what are the perils and pitfalls and stuff that we all take for granted? Because we just design, most of us just design stuff that plugs into the power point or power from batteries, you know?

Chris Gammell: Look, it's been around a very long time, the industry, and it's sort of a little hidden industry. It sort of runs in the background and you don't really know about it until something's wrong. Yeah. But, you know, in Australia we have our distribution network providers who sort of run the poles and wires business. And then you've got all your generators and you've got your transmission. And so, you know, in Australia we've got probably three or four, you know, big generators in New South Wales and they push out all our power. They push out around 600 or 700 megawatts a second.

Dave Jones: Well, are you talking about the actual generators or the generating companies or the generation companies?

Chris Gammell: They're all, there's sort of unusual ownership arrangements on a lot of them. But there's, you know, to provide the power for the whole state we've got to have a couple of generators. And we've got some big ones that are all coal-fired, steam-powered prime movers. And then there's, you know, a few little ones. There's some solar installations, some wind installations all around the place. But, you know, all combined they all get their power and they push it out onto the transmission network. And that's a separate group. But, you know, the generators, there's a few in the north of the state, a few in the south. They're scattered around. And they all send their power to marshalling stations or marshalling yards. And these big distribution centres, there's one, I think, just near St Mary's there, they all send their power directly to that distribution centre. And then from there, it's sent out via transmission networks. And that's when it gets to your, you know, the likes of Ausgrid, Endeavour Energy, Essential Energy, those three main providers for the state. And from there, off they go on their little 132kV towers and head out to all the zones.

Dave Jones: Little, little, 132k is little. And not to me. It's funny.

Chris Gammell: Dave, we use the term low voltage for LV up to about a thousand volts. So we consider that low voltage.

Dave Jones: Right.

Chris Gammell: And then we have our high voltage.

Dave Jones: I think in the realm of electronics, it's officially 40 volts or 42 volts or something, isn't it? So something like that is considered low voltage in the electronics?

Chris Gammell: Probably touch safe, I think, maybe 50, 60 volts DC.

Dave Jones: Yeah, something like that. Something like that, yeah.

Chris Gammell: Yeah, it's quite a big industry. And there's actually a lot that goes on. There's quite a bit of engineering that goes into all of it. Not only all the work that gets carried out in the street, all the poles and the wires that have all got to be put in, maintained and looked after. But there's a lot of engineers that run in the background too to design all the protection systems for the transmission and the zone subs. So I don't know where the best place to start is, but... Generation? Yeah, the prime movers. They're mostly coal driven, coal fed. The coal comes in usually on conveyor belts from a nearby coal mine or like a big, they have a big gathering area where they just pile up the coal. And there's a big, like a feeder that grabs it and crushes it, powders it and then throws it into the furnace. There's usually near every generator, there's usually a water source and that water's brought in and they make steam and they drive a turbine and they call that the prime mover. It usually pushes out around 12 kV on the rotor and they then put that into their local marshalling yard and bump it up to usually in the 330 to 500 kV range. And then they send it out to the various areas for splitting up.

Dave Jones: Why does the generator only output 12 kV? Is that just like the winding, like breaks down and stuff like that in the motors in the gen?

Chris Gammell: So sort of, you know, high voltage machines, they're sort of hard to insulate at the best of times. Yeah. And so when you've got this big spinning generator that everyone has to work on and, you know, they take as long as three or four buses, some of these things, they take up a big whole floor. And yeah, they just, they sort of limit the output. And then, but of course, for transmission, we want that high voltage to have that low I squared R loss. So they push it up to the 330, 500.

Dave Jones: And they do that straight away because you don't want to be transmitting huge power from the main generator any sort of distance. You want to bump it up to 500 kV as fast as you can or as near to the gen as you can.

Chris Gammell: Yeah. And they'll, yeah, they'll bump it up straight away and then send it out from there. And that's when Transgrid get a hold of it. And they'll send it out throughout the state. And they'll manage that sort of higher level generators coming on and off load and picking up the load. Because the generators, they do have a governor that holds the generator at 50 hertz. So as the power, you know, load increases, the throttle will open up and she'll put a bit more power in to keep that 50 hertz going.

Dave Jones: But on average, over a long time, it's almost precisely 50 hertz. Is that right?

Chris Gammell: It really is, yeah. Yeah. It's very good. Pretty bang on. Yeah. It's actually kind of fascinating the way, you know, the synchronicity works across the network that, you know, the generator is spinning at 50 hertz and it's, you know, pushing and pulling that electric field right out through the neighborhoods. And, you know, there's three phase motors in premises and industrial processes that are all spinning at the same speed. And they're like a, it's like the big generator sort of divvied up its work. And it's all in all these other smaller machines, but they're all still running as well.

Dave Jones: How do the different generator plants synchronize together? Is that done via like some, you know, comms, like optical fiber network? Or do they, well, I guess this isn't precisely your area, but, or can they just like, one of them is like the master and the others are kind of like slave and they just know?

Chris Gammell: They're all synchronized. One of them could drop on and off and it wouldn't, you know, wouldn't change the others in any way. Yeah. I guess that that's why, you know, the black start would be a problem where you don't have a synchronized source.

Dave Jones: You've got nothing. The grid, the entire country's grid is completely down and you've got to bring it up from scratch. Yeah.

Chris Gammell: And that's why, you know, we've got, there's things like the hydroelectric system, which can just instantly push out, you know, about 20 or 30 megawatts straight away. And that's enough to supply the rotors in the big prime movers with some current.

Dave Jones: Ah, got it. So if you had no hydro. So if you had no, none of that instant hydro energy, how would you start up the big gens from like nothing?

Chris Gammell: I'm not sure they could have, I mean, it'd be pretty unlikely to have, you know, all of the generators stop working. The protection systems isolate all that stuff straight away. So that it's unlikely that they would stop completely. I'm sure.

Dave Jones: What is the biggest outage we've had here in this state, New South Wales? Because I like to me, I've, I've lived here my entire life. Right. So it's always been almost a hundred percent reliable. I can count the number of blackouts like on two hands, like, and, and like they don't really last longer than like, you know, a couple of hours at absolute most.

Chris Gammell: Yeah, no, it is really good. Um, obviously everyone gets their outages when there's program work, you know, you get your notification. Oh yeah, of course. They knock the power out for a day, but you know, unplanned outages, there's a fair few in the regional areas, you know, under storm or bushfire conditions. They're the ones that seem to cause the most outages, but, um, and then sometimes you get the cable interconnects. Like, I don't know if you remember that. I think there was one that was, um, across the harbor there. One of the primary cables failed. The secondary cable picked up the load, but it just couldn't handle it. And it failed. No, I don't, I don't remember that. In Sydney somewhere. Um, but that was, you know, and that was about a half a day or a day or two, but yeah, we're pretty fortunate here. We don't have long-term rolling blackouts.

Dave Jones: Yeah, I mean, of course we had the famous one in, uh, South Australia that, that actually resulted in, that was bushfire related. Wasn't the poles just totally collapsed or something. Or storm related. Yeah. Yeah.

Dave Jones: Or something like that. Yeah. That was a huge, and that took down like, you know, a whole grid. In fact, the, um, the control center for all of the Eastern seaboard is here, just a stone strove from my lab. Um, and the bastards wouldn't let me in.

Dave Jones: Apparently that this is where they are. This is where they control it all from. Um, it, they don't just control this state. Apparently they control the whole Eastern seaboard. Okay. Is that, that's what they told me.

Chris Gammell: I'm not sure. I know that literally every, um, company has their own control rooms. I can only speak, the company I work for has sort of a North and a South, uh, control room. And, and they monitor all their incomings and outgoings. And, um, you know, they can switch pretty much anywhere on the network and switch around any sort of problems. And yeah, they do have to, I think they have to look at, you know, what the, um, potential demands going to be like. Like they sort of start to get, you know, really concerned on the really hot days. They make sure they've got a plan and they've, you know, bought enough power for the day. But other than that, it's, it's fairly simplistic and each of them all coordinate. But when there's, when there's outages that, um, you know, go between, uh, companies or between systems, that's when they have to do a bit more coordination because you might have to ask someone at the other end to do some switching for you.

Dave Jones: You know, do we get power from other States or are we a net export? Do you know Dave?

Chris Gammell: I don't know. I'm, um, I'm not going to say I'm, um, a basic liney, but I, but I, you know, you know, there's a bit of a thing at, at, um, in, in the power industry about lineys and fitters, you know, who's the best, but, um, you know what I mean? But, um, out West you find they're pretty much identical roles, but in the city, you know, you've got your lineys and your fitters, but, but, um, you know, from, from a distribution network point of view, we don't see a lot of that.

Dave Jones: Um, right.

Chris Gammell: And because we haven't had many outages, we've never really even had to sort of deal with, deal with it, I guess.

Dave Jones: But got it. So, so what is the highest voltage that you deal with as a line, as a linesman?

Chris Gammell: Yeah. So, um, 132 KV is the highest network voltage for our towers. And that will be the same for people like Ausgrid, Endeavour Energy and, um, Essential. They're the New South Wales providers. And we'll, we'll get the power at 132 KV and that comes from Transgrid, their marshalling yards. And from there, they'll bring it into the zone subs. You, you probably see the sort of almost, um, like look like city buildings with a, um, you know, like almost like a dwelling, but a bit more industrial. And then they've got the gates and the big fences around them. Yeah. And they'll have some outdoor transformers. Sometimes they'll have outdoor indoor transformers. They're like, uh, they put walls around them, but they're open to the sky and they'll buck the one 32 down to 66 or 33.

Dave Jones: What are those, are those walls just like fire containment? So it doesn't spread to the rest of the facility?

Chris Gammell: Yeah. Although, you know, touch wood, we haven't really had many of those, but yeah, things like that. Just also maybe visual amenity as well, because they have to be in neighbourhoods. Um, all of them are bunded as well to catch any spills if there's anything like that was to happen. So they're all, they're all pretty well maintained like that. Um, and, but they, they're what we call our transmissions own subs, and they don't really have any customers connected to them. They just take that one 32 and then they split it up to send to our other zone subs, which are the ones that are a little bit closer to town potentially.

Dave Jones: I got it. Okay. So we're still talking outside of may like outside of Sydney here, are we?

Chris Gammell: Um, no, there's a, there's transmission subs. There's one in Blacktown, there's Parramatta, there's transmission subs all around the place, Hoxton Park. Um, but they're, they're sort of, one of those might do, you know, several suburbs or more provide those 66 kV transmission lines. And that's when we sort of lose the towers. And now we're going on to our poles.

Dave Jones: Right. So we're talking, so it, transmission is usually 330 or 500, right? Yeah. Main transmission from the power stations. And then they drop, then 132 is the next level.

Chris Gammell: That's right.

Dave Jones: And then 60? 66. 66 is the next level after that. Yeah.

Chris Gammell: Okay. Got it. And that's when we get onto the poles. Often it'll be maybe a vertically constructed concrete pole, or maybe timber poles. And, um, one of the tricks with insulators, if you count the number of rings, you can kind of get a rough idea of the voltage. Maybe there's six, six skirts on the insulator. You're looking at 66 kV. You might see three skirts. It might be 33. So the, you know, from there, that's when we get to the zone subs and there'll be one of those per suburb. You know, there'll be one in Penrith. There'll be one in Blacktown. There'll be one for every suburb. They're quite smaller. And that's when we take the 66 and there might be a couple of transformers hooked up to a bar. And then from there, they'll have an output of around 11 kV. And that'll, that'll connect to a bar and hanging off that bar will be a number of breakers, 11 kV breakers, distribution breakers. And they're the ones that then go out into the streets on the poles again. And they're the ones that power up the transformers that are on the poles or the pad mount transformers that then produce our low voltage.

Dave Jones: And which is a 240 volt, uh, three, well, the, uh, three phase. Sorry. Yes. I'm old school. Sorry. They changed that in like the 1980s. Didn't they?

Chris Gammell: It's a bit silly. It's, uh, I think we're trying to align with the rest of the world. It's, it's plus 10% minus six. So two 53 to two 17, I think something around there. The point of it is, um, is that, um, you know, some people are bringing their two 20 volts up to two 30. We're bringing our two 40 down to two 30 half of that, the one 15s. Some of the one 10 countries are coming up to one 15 and so on. Okay. So I think, I think there's some alignment there. They're just, obviously it makes sense to, you know, minimize the number of voltages in equipment around the world.

Dave Jones: Yeah, of course. Who, who makes the trend? Like who makes the transformers? Is there like one company that special? I know there's lots.

Chris Gammell: Lots, lots. Um, so our friend Chris ABB, I believe they make a lot of really good, lots of gear. Uh, they make a lot of switch gear and transformers, but, um, you know, they've been over the years, there's been various manufacturers, um, you know, contribute some of the transformers like a one 32 to 66 KV. You might need a one year lead time to get something like that.

Dave Jones: Oh, okay. Potentially.

Chris Gammell: And you may need to get it shipped on a truck that will block three or four roads. You know, three, four. I've got a video of one of those.

Dave Jones: I, yeah, I actually haven't uploaded it yet. I've, yeah, I'll put it on my second channel. We, I was just going in there. I was just driving through the outback and we had to pull off to the side of the road. The cops came past, waving everyone off. Here comes this huge truck with this massive ass transformer hanging over the sides of the truck, you know, so they had to shut down the whole highway.

Chris Gammell: Yeah.

Dave Jones: Just, uh, yeah.

Chris Gammell: A lot of those own subs will have anything from sort of one to four or five or six transformers potentially. Um, do you want to talk a bit about the arrangement of the transformers and the way they are connected? Yeah, we can definitely do that.

Dave Jones: I I've just got one question about, before I forget about the, um, industrial business parks like I'm in, um, are they, are they treated any differently power wise to like a regular suburban suburb? Yeah, a little actually. I assume they'd use more.

Chris Gammell: Yeah, they do. And so, um, a lot of them, they're what we call, um, HVCs, high voltage customers. And some of them will take the, take the, um, power straight from, uh, the company at, at 11 KV. And they'll have their own transformers.

Dave Jones: Yeah. Cause my, uh, building, my, my building here has like a massive room that powers this entire building. And I assume that's 11 KV.

Chris Gammell: Yeah. You'll see, you'll see them. They'll have, you know, warning electricity and there'll be a locked door, um, maybe vented and things like that. And, um, yeah, they'll have an indoor transformer. That's a ground level. Yep. Yep. So a little bit, a little bit tricky to work with and manage, you know, because it's right there at ground level. Um, right.

Dave Jones: Oh, maybe you're the guy to give us a guided tour of a room like that. Would that be your area?

Chris Gammell: I would love to, to somehow get you a tour of one of our nice new zone subs. Um, I might have to try to ask around for you. No, I'm talking about my building here.

Dave Jones: Oh, okay. I'm talking about my building cause I can get access to the room. So.

Chris Gammell: You need to, you need to, um, wait for someone that's, you probably won't get access to the room. Probably won't get access to the transformer room. Right. It definitely will be keyed. Yeah. That's, but like you say, they do, they have a transformer room. Sometimes they might have a couple of the green pad mount boxes just out the front and they'll have, you know, low voltage cable, quite heavy duty cable running into the building and they'll have their own switch gear in there and their own protection distribution boards. But yeah, a lot of them do. They have an indoor transformer. Yep.

Dave Jones: Right. Interesting. So how, like, do you have problems with like the government say, oh, I'm like, oh, we're building a new suburb. Boom. Right here. And we want to get it done. You guys go, uh, uh, sorry, we don't have the spare power available. Is that a, cause I, I know that happens with sewage. I know that happens with like sewage and water and stuff. It's like the government says, we're going to install a new suburb. And then the authorities go, no, sorry, we don't have the excess.

Chris Gammell: Yeah. No one wants to get told second, but they, they generally have to apply. I think for a certain size of connected load, you, you must advise the distribution provider that you intend to do it. And they'll take a look at the infrastructure that they have in the area. And then there's a little conversation around how it's going to be provided below a certain amount though, your average person with a house, not really something you have to talk to them about.

Dave Jones: They've got that capacity, but yeah, of course, but an entire suburb, if the government says, well, we're going to plug a new suburb here. Like a suburb takes a lot of room.

Chris Gammell: There's been a lot of building lately around the airport sites and everywhere else. And, and, and yeah, it is, it's planned well in advance.

Dave Jones: Now getting back to, sorry, we've got sidetracked. What were you going to talk about the.

Chris Gammell: Oh, just, just the trans the way the transformers are hooked up is it's really interesting. They, the, the inputs generally come in and the outputs, they generally come into what's called a bar. It's just basically a bar, a metal bar.

Dave Jones: Okay. It's physically a bus bar.

Chris Gammell: Yeah.

Dave Jones: Physically a giant. Is it copper? It's aluminum mostly.

Chris Gammell: Most of them are aluminum because it's lighter and it's almost as conductive. Yes.

Dave Jones: And people don't know this power lines. Please correct me if I'm wrong, but practically every power line, every street pole, every 500 kV transmission line, it is not copper.

Chris Gammell: It is not copper. There are some older, older areas around Blacktown and places like that. You'll notice they have a green tinge that are copper, but they're pretty rare. You might see a streetlight conductor, which is a separate conductor underneath and that's often copper, but it's extremely heavy. I think the density is maybe eight or 12 or something. And, and you know, aluminum is in the two.

Dave Jones: Oh, you mean even though it's not as good a conductor, you're willing to trade off that force for the weight.

Chris Gammell: It's very close. And you can up the size of the conductor slightly.

Dave Jones: Right. Yes. Got it to compensate. And it's still lighter than the coppler equivalent.

Chris Gammell: It is. And the spans and the length of the spans that you must do can, I mean, we've got spans that can go up to six, 700 meters.

Dave Jones: Oh, wow.

Chris Gammell: Wow. Cheers. The stuff you see around in the, in the burbs, the 80 meter stuff, that's tiny. There's stuff that can go kilometer. Wow. Yeah.

Dave Jones: Wow. That's a heck of a, that's a heck of a droop on the wire. Wow.

Chris Gammell: You should try being the linesman that's got to crank the tension up on it.

Dave Jones: I was going to say they would have tensioners, right?

Chris Gammell: They've got to go up there periodically. Yeah. They're like, we call them lug alls. They're like a ratchet strap on your car, but obviously they're engineered. Um, you put a strap around the cross arm, you do what's called a come along, which it's kind of like, uh, you've been abseiling, haven't you? You, you know, you know, there's a device I think that lets you climb and only sort of goes one way. Yes. You can ascend up. Yeah. Yeah. Just one of them. You put it on the wire, you push it out. It goes outwards fine. You hook it up to your lug all and you start cranking it up and it pulls the tension in. And then you, um,

Dave Jones: So do they have to adjust those differently during the seasons? Cause I imagine summer's going to get hotter. So it's going to expand and droop more maybe is that a thing?

Chris Gammell: It does. They do sag. Um, they do sag based on temperature, but all the, all the calculations are done with the maximum sag and maximum current.

Dave Jones: Got it. Okay. So you don't have to adjust it during the year. You just have to periodically maintenance kind of.

Chris Gammell: All the conductors, they're actually all quite different. Some of them are multi, they're all multi stranded, but some of them are an aluminium alloy. Some have a steel reinforcing core in the middle. You've got your, um, you've got your covered conductors. You've got your insulated conductors. You've got, um, bundled conductors and they're all quite different and they, they all have different roles. And if you start looking around the network, you'll, you'll start to identify some of the different ones. So, um, well just back on the transformers, I guess, cause that's, that's where I suppose some of your engineering crowd might be kind of interested is that each of the transformers, um, you know, they hooked to bars and the bars might have a breaker in between them to ties different sections of the bar together. And then each transformer itself will have a bar facing say the one 30, sorry, a breaker facing the one 32 and they'll have a breaker facing the 66 on the way out. Each of those breakers will have a VT, a voltage transformer, which takes a proportion of the voltage and takes it down to about a hundred volts. So we can measure the voltage on the bar and come in and out of the transformers proportion. They'll also have a CT, a current transformer, and that'll measure a proportion might be a 200 to 5 ratio or an 800 to 5 ratio. That'll measure a portion of the current.

Dave Jones: How much loss is there in one of those current shunts?

Chris Gammell: Not a lot. They're not current shunts per se. They're, um, they're, you know, when you get your, um, you know, your multimeter, your multimeter, that's got the, the clamp. They're a current transformer. Yes.

Dave Jones: They're a current transformer, but they still got winding, winding loss in them.

Chris Gammell: I guess you would call it one wire primary, but yeah, you just sample a portion of that. And that's how you sort of not only just look at the load going in and out of the transformer, but that's how all your protection works. So obviously you've got to protect on overcurrent and you've got to protect loss of phases. You've got to look at the voltage and monitor everything. And so, you know, all of those devices in the yard. And if you ever, you know, look in a yard, you might start to recognize some of them. They'll all, um, you know, sample the voltage and current, and that'll all come back to the SCADA control systems. And that's where things get crazy. This, you know, panels with relays in there that will measure everything and, um, you know, trip the breaker accordingly. But the arrangement of everything's kind of interesting because back in the old days, um, you know, your normal spinning meter that's inside your house. Well, it's, it's, um, it's technically a motor. It does measure power.

Dave Jones: Yes. I've actually done a tear down video on those. They're fascinating. Absolutely fascinating. Absolutely fascinating.

Chris Gammell: Well, can you imagine getting one of those, but instead of hooking it up to a source, hooking it up to a CT. And so that, and imagine that it, imagine that it had a set of contacts on the disc and when the, and it's, let's say it's, um, you know, receiving normal current, it sort of slips and doesn't move, but above a certain amount of current, it starts to make the disc move.

Dave Jones: Oh, and they'd physically have contacts on that. Yeah. Which then it detects that and then cuts it off.

Chris Gammell: Yeah. And it works well because it follows the same inverse time constant. Really, the more current delivered to it, the faster it turns. Yes. And so it may only turn a quarter or half a turn, but you can literally put pegs in the disc that will trip a set of contacts.

Dave Jones: Wow. So it's a mechanical, it's effectively a, a mechanical solution.

Chris Gammell: But we've gone past that now, but.

Dave Jones: Oh, okay.

Chris Gammell: Right. But they exist still. There's a few still out there with, but, but you know, the, the same sort of functionality has been replicated in software. Well, not in software, but in hardware, electronics, hardware. So, um, I can, will be programmed, but you know, breakers, they're interesting to be because if you imagine an 11 KV distribution breaker, feeding power outside onto the poles and wires has a fault or over current. It may, it will trip the breaker. And the break has a set of contacts that will tell you if the break is open or closed. If it doesn't trip or the moment it goes to trip, the upstream breaker timer also starts because if that break, it doesn't trip that transformer will be in trouble. Oh, got it. So the next point of call is to turn the transformer off and trip it.

Dave Jones: Oh, okay. So it talks upstream and goes, Hey, I've got a problem. Be on standby, be on ready timer for. Yeah. So both timers will start.

Chris Gammell: And if the, if the breaker doesn't open and those contacts don't show that the breaker opened, then the upstream breaker will trip.

Dave Jones: Will trip just in case that yeah.

Chris Gammell: It will absolutely trip.

Dave Jones: So that's, that's a fault prevention on top of a fault.

Chris Gammell: Yeah. And that's why we probably wouldn't have that runaway problem because our protection is really good like that. Most of it's duplicated with standby relays as well, especially in the transmission zone subs. They're also battery backed up as well.

Dave Jones: Right. Interesting.

Chris Gammell: And the control room knows what's going on as well.

Dave Jones: Right. What happens if ironically power fails to the control room? You have a battery backup, DC battery. Right. So there is a DC battery in the substation. Yeah, they do have AGM batteries there. Right. Yep. Okay. All of them. Yep. Right. I didn't think about that, but yeah, ironically, what if the power to the power station fails?

Chris Gammell: Yeah. The testing and commission and building of those is really fun job. Like it's a really cool, interesting job because I don't know if you've seen them. They make these things called dobles. They're like a big power supply that's fully programmable and can put out, you know, voltages up to a thousand volts at whatever frequency and current you want. And then they have sort of logic inputs that can, you know, that you can see when they've triggered. So you might hook it up to a breaker. You might wrap, wrap the output around the CT a few times to double up or quadruple up the current, inject some current and see if the breaker trips. When the breaker trips, when the breaker trips and those contacts open, the double will tell you the time in milliseconds, you know, and then you can check all your tripping curves. It's a lot of, a lot of fun to build all that, that gear. There's, you know, like I said, CTs, VTs and the breakers and there's even standby equipment. The breaker might be split in half. And so if a transformer fails and locks out, the bus tie breaker might close and bring in the standby transformer or put all the load onto one of the other transformers as well.

Dave Jones: Okay. So you will, every substation will have a standby transformer.

Chris Gammell: Will it not every substation, but a lot of, a lot of electrical equipment can handle overload a lot higher than its normal load. So maybe 150, 200% of its normal rate of capacity.

Dave Jones: Okay. That's quite a lot, but, but you wouldn't want to do that for like a week or something you want to, you could do that for a day or half a day or something.

Chris Gammell: You might pull a transformer out of service to work on it. Oh, okay. Yeah, of course. So you might isolate and pull it out of service. Yeah. And then of course you've lost that, you've lost that backup capacity, but it's usually, you know, been planned around. They'll, they'll have a, they'll have a plan.

Dave Jones: Right. So what are the usual failure modes that cause a transformer, like a substation trip? What's, what's the usual fault down the line?

Chris Gammell: They don't really, the transformers don't really fail, but mostly.

Dave Jones: Mostly. No, no, I'm talking about what, what causes the breaker to trees.

Chris Gammell: Trees, trees on power lines.

Dave Jones: So it's, so it's shorted power lines, right? So it's shorted and open power lines. Because if people aren't aware, they, most transmission lines in that you see like power poles and stuff, there are three phases. That's why they have the three wires on the top.

Chris Gammell: Yeah. So the high voltage networks, three phase and it's three wires and they come into the transformer and they terminate in a delta configuration. So they just, it's like a triangle. Imagine the wires attached to each point of the triangle. The sides of the triangle are one of the coils in the transformer. And then on the secondary side, you'll have four wires because it's in star.

Dave Jones: Yes. Oh, star and delta transforms. I kind of remember those from, I don't, I don't think I could do it today, but like straight off my head, but you know.

Chris Gammell: One of the questions I like to ask the, the apprentices is, you know, what are three phases add up to? Now you hear a lot of things, but do you want to take a guess, though? What three phases add up to?

Dave Jones: Three phases adds up to, I don't know. Three phases. No, it's, you're obviously a trick question and I'm just going to embarrass myself. Yeah, zero. Zero.

Chris Gammell: Zero, right. Because that's where that neutral point, the center of that star, that's where it's derived. Yes, okay.

Chris Gammell: And that's at ground potential. Now we actually get our neutral.

Dave Jones: Now, yeah, it's all flooding back. I totally remember. Yeah, we had that question in an exam one time.

Chris Gammell: Yeah.

Dave Jones: I totally remember that. Yeah.

Chris Gammell: Oh, the, the, the mathematics around phaser calculations. It's not fun to do. No. Three phases are out of phase by about 120 degrees.

Dave Jones: I can kind of remember enjoying it at the time, but I can bet, you know, it was like, meh, how am I going to use this?

Chris Gammell: Well, our power engineers do. They, they look at bolted faults, what we call a bolted fault, which is like basically a basically as if the wires were bolted together, two phases. What's going to be the negative sequence current for that? You know, which, which way is the voltage going to go? What, how much current's going to flow? Because the amount of current flows depending on, depends on the impedance of the transformer. They have an impedance of around seven and a half percent. So, um, that means, you know, a hundred divided by 7.5, whatever that is, um, is, you know, if they're normal currents, a hundred amps, it'll be, you know, 20 times a hundred amps. It'll be their fault current, you know?

Dave Jones: So, right. Cause I can imagine that's tricky. Imagine if, you know, your longest transmission line, you can imagine as the short right at the end of the transmission line, you've got all the other loads on there. Would you still be able to, how do you pick that up?

Chris Gammell: We have two types of protection. We have, well, there's lots of protection schemes. There really are. And they're individually tailored and designed for the kinds of equipment and that are present there. And the back, like the backup cycle said, if there's a second transformer or not, a bus tie breaker mightn't be there, you know, all those sorts of things. But yeah, we, we use an, an earth fault protection and that's like, um, you know, a certain amount. So we, of course we've got all the usuals under voltage, over voltage, over current protection. They're all there, but for a conductor, um, you know, touching the ground or earthing or something like that, a fault like that. We use, um, two types. We use a sensitive earth fault protection and that's a lower current, but for a longer period. And then we've got our earth protection, which might be, you know, five amps or five seconds would trip. But a sensitive earth fault might be as low as one amp, but it might need about 30 or 40 seconds to be, you know, seen for that length of time. And it says, right, there's something not right here.

Dave Jones: Because you don't, it's a trade off, wouldn't it? It'd be a trade off between actually protecting your transformer or another infrastructure and allowing, like, nuisance tripping. Like I've had, like, I came back from holidays one time and all my fridges were filled with moldy growth because we, our power fight, the earth leakage circuit breaker tripped. Yeah. For tripped. And then it just, yeah.

Chris Gammell: I think that's why you got yourself that little, um, that little power bank.

Dave Jones: That, that little power bank. Yes. Yeah. The battery bank thing.

Chris Gammell: Yeah.

Dave Jones: It's like, yeah. Bloody annoying. Yeah. So it'd be a trade off, right? Between sort of nuisance things, because your job is ultimately to deliver power to a massive load of thousands of customers, right? Tens of thousands of customers while protecting your equipment. Oh, it's a million. Million, right?

Chris Gammell: Yeah. About a million plus customers.

Dave Jones: Oh, wow.

Chris Gammell: About 32,000 or so of those are on, uh, what we call a life support customer as well. Someone that needs electricity to keep their medicines cold, to help with their oxygen concentrators.

Dave Jones: Hospitals would be on a totally different, would, you know, how would you wire up a hospital different, would you give them a backup transformer and a priority? They have their own feeder usually.

Chris Gammell: They don't usually, that feeder's marked in the zone sub so that we know that it is a hospital feeder. They also have a lot of their own generators as well.

Dave Jones: Of course.

Chris Gammell: Yeah. There's a lot, you know, 430 odd thousand power poles around.

Dave Jones: Oh, what is the difference between, yeah, I mentioned this at the start of the thing, underground and, uh, poles. Cause my house and suburb is all underground power. And I like, that's a good thing for, as far as the consumer's concerned, cause you don't see these pesky power poles. There's less potential interruptions from trees and lightning and cars hitting them and you know, all sorts of things. So what is the difference? And do you, do you guys have a, uh, preference for underground? Is it more difficult to work on?

Chris Gammell: What kind is it? From what I understand, all new developments need to be, um, underground. They need to demonstrate a reason why they can't be or shouldn't be. They might be a rural subdivision, but in general, they, they, they like them to be underground. I guess in a rural area, the aerial conductors, they're very easy to put back up in the air. They're very fast to restore supply. Um, there's some associated, um, let's see, not difficulties, but when you switch with underground, it's inside cubicles. Um, it's a little different the way we do underground switching. You can't trace the conductors as easily. So like to, to be a switcher on the network for underground is a slightly higher qualification in general, but, but underground, you're right. It's when there's a fault, it might be a little harder though, because you, you might have to dig up everyone's, you know, the front, front driveways or whatever.

Dave Jones: Yeah. Right. But, um, but, um, but faults like, uh, water ingress in the, in the wires underground. Is that a problem or?

Chris Gammell: Yeah, it doesn't really, it doesn't. Okay. Does it right? No, not at all. Um, they, they also, believe it or not, the conductors actually are a little cooler in the ground. Um, you can overrate a conductor and it's buried. Right.

Dave Jones: Okay. So they, you could potentially get away with a lower rating cable or more, more power for a given.

Chris Gammell: Just that they, they're just a little bit more secure down there as well. And they have a benefit of the cooler, cooler environment as well. Um, and then. Um, and then.

Dave Jones: Is there any extra loss in terms of like power factor and capacitance and all that sort of jazz? Is that. Mm. Cause I think it makes a difference on really high voltage DC. Yeah.

Dave Jones: Yeah. You do.

Chris Gammell: I mean, you, you get, um, you do get a little, like when you, it's funny when you're testing cables, if there's, um, you got three phases and only one's energized, you will see a voltage on the other two phases. So you do get that induction, but, um, not that I know. A lot of them are, um, still copper actually, a lot of the underground stuff. So that's.

Dave Jones: Oh, right. Oh, cause weight's not an issue anymore. So I guess it's.

Chris Gammell: I wonder, would it be cheaper copper or.

Dave Jones: Aluminium.

Chris Gammell: Aluminium is a lot cheaper from what I understand. It's just cheaper.

Dave Jones: Okay. Yeah. Yeah. Cause obviously cost is a big part too. Yeah.

Chris Gammell: Yeah. Cost in electricity has become a bit of a thing lately. And as you know, like the renewables are just going crazy at the moment. Oh yeah. Yeah. A lot of things happening in that space.

Dave Jones: Right. You got any personal thoughts on that? Whether or not that's a good thing, bad thing, troublesome.

Chris Gammell: I think it's good. I, I, I don't know about you, but I've got, I've had solar for a few years now. Yeah.

Dave Jones: Same here. I've, I've had it forever.

Chris Gammell: Yeah. Um, I'd like an electric vehicle if I could.

Dave Jones: Yep. Got one.

Chris Gammell: They're great.

Dave Jones: But they're not for everyone. Of course, you know.

Chris Gammell: No. Community batteries are a sort of virtual power plants. I like the idea of say, like at the moment, you know, you sell your power to the grid. It'd be kind of nice if they were to bank that power somehow. And, um, you know, give you the chance to buy it back in a battery.

Dave Jones: Yeah. Like, I know that I'm generating excess solar into the grid. I know that my neighbors are using it. Why can't like, we have like a little neighborhood monitoring thing that like, oh, I know it's being used by my neighbor. Oh, I can just charge my neighbor. And like, you can buy, literally buy it off your neighbor.

Chris Gammell: Yeah. They have community batteries around the place too. And they, they actually, um, and virtual power plants, I think they call them, but they, they also increase resilience a lot too. Um, we've got some places down the coast that were badly affected by bushfires and they can get isolated for quite a while. Because I think the thing about Australia, it's such a large country. We've got these transmission lines running everywhere. Um, you know, and the power does come from a long way from where it's consumed. And so, you know, it's got to pass through, you know, rural areas and they're often subject to a lot of, you know, disruption from storm and floods and fires and stuff. Yeah. And it can impact the communities a lot. So having a little local storage is probably a good idea. I mean, I, I like the idea of, um, a bit of renewable scattered around. Isn't that what we're working for anyway? I mean, you know, working towards a better sort of.

Dave Jones: Oh yeah, no, totally. We want to, you know, to get it. Yeah. I would like, I mean, what I think Australia has the highest solar uptake in the world, right? Like 35, even 40% of homes have solar now.

Chris Gammell: Well, it's massive. Yeah. It's a, well, we've got, supposedly we've got over 200,000 customers that have some sort of renewal, renewable energy system at home. That is just in.

Dave Jones: Out of a million.

Chris Gammell: Our state. Just in my, the company I work for. Oh, just the company. So yeah. Yeah. So we're, we're just sort of Western Sydney, sort of, we go sort of north of Kandos up there to Bylong and Katoomba and South Dalladala and into Parramatta and big area.

Dave Jones: That's just, yeah, that's a huge number of people. Now, if you're a linesman, you're working on a line, how much of a fear do you have of, oh, somebody's installed a non-compliant solar thing? You've, you've gone in there. You've actually locked out the grid with your padlocks and everything. Yeah. We actually don't. Some bastards.

Chris Gammell: I tell you, Dave, if I was fearful, I'd be worried we're doing something wrong. We, we are very good at protecting ourselves and our, and the work, you know, my mates. Um, we always, um, isolate. We test the isolation. We lock it and test it. We danger tag it. And then we bond it. So we generally with the high voltage network. Okay.

Dave Jones: So you would strap it. You would have it. Yeah.

Chris Gammell: We run special, special, highly rated, um, uh, bonds between the, between the phases and then down to earth. And when it comes to, you know, our, the solar installations, we don't necessarily, um, go through and isolate them all from what I remember. But like I said, I just have to preface this. I have been in the, out of the field for a couple of years now, just a couple, but I keep my mind everything. And yeah, they, they use bonds on the LV network now as well. And they, you know, just because all, all our, um, the, the, what islandings, that what they call it when they.

Chris Gammell: Yes.

Dave Jones: Every, every solar inverter in this country that's sold in this country must have auto islanding, which means that if the grid fails, you can't, it, it will shut down. It'll shut off its output and it won't export. If it doesn't see that.

Chris Gammell: Yeah.

Dave Jones: If it, if it doesn't see the grid, it won't, uh, generate any power. That's why if power to my home fails, I don't care how big my solar system is. It's just going to shut off. You can't use it. Right. You can't use it. So you've got to have like a local battery. You've got to have an AC battery solution, or you've got to have a local islanding, um, battery solution at your home. So yeah, it's got to shut off. Yeah.

Chris Gammell: So we, we don't worry too much when we're working on the network because it really is safe and it's really isolated. Well, um, and we have a lot of paperwork too. So after you, um, complete the isolation, you all sign on everyone in the party signs on, um, to an access authority, which, you know, um, it details where the isolations are carried out. So every member of the team knows where the isolation is. So they make sure they're working inside it. And there's a set of visible earths hanging as well. So I was going to ask that where, where is the earth in point?

Dave Jones: Like if you want to isolate the power pole above.

Chris Gammell: Yeah. The hang them on the wires, you go up with your EWP, you test it, and then you hang your earths on those wires and then they come down to the ground and you drive a stake in or use the earth. Oh, okay.

Dave Jones: So you'd physically drive in a stake, right? Yeah.

Chris Gammell: Um, or if there's an earthing point that's suitable on the pole or, but, um, you know, the work party can see those earths that are at the fringes of their work site. They can physically see that they're on there. So they know not only have they signed on, seen the isolations take place, seen the testing, but then they can see those earths and know that they're inside that isolation where it's safe.

Dave Jones: Right. So, but how, if you're driving a spike in, how would you know that's an adequate ground? Cause that has to do with the soil moisture and the whole.

Chris Gammell: It's more, it's more, it's more the, um, the short circuit protection. Um, so the, the earth has, the earth has three connections on it that run between the phases of the HV. So the three HV phases are bonded together. Oh, got it. Okay. Right.

Dave Jones: And then you have an extra lead that runs down to the ground as well. Oh, okay. So really you're doing short circuit protection rather than earth leakage protection. Yeah. Got it. Okay. Yep. Sounds good.

Chris Gammell: And our, our, um, our isolation systems. Um, it's funny. I'll tell a bit of a story. I came from Telstra or was telecom back then. Yeah. And, um, you know, it was very digital. I came here and I said, Oh, I helped, you know, as an apprentice, I was like, what are we going to do? How are we going to turn the power off? You know, what app have you got? What, what, what are you going to do? Noob. Yeah. Noob. We got this stick. And I said, what do you mean? You're joking. No, we got a stick and it's literally an extendable stick that's tested. It's insulated and tested regularly. Um, and you reach up and there's plates. So it isn't just a broom handle? No. And they have, you know, under our, under our safety rules, you must look at the date on it when it was last tested. It must be a date. We're very good like that. It's, it's really good and, and it works really well. And yeah, they just put it in. And yeah, they just pull the blades. They're like a knife blade and they just pull the three blades. Um, and they hang down.

Dave Jones: Okay. So you would insert this long, so you would insert this long pole into like a tube on there and then physically pull it.

Chris Gammell: It's got a little ring. You put your hook and you pull the ring down and the blades come out and it de-energizes. And yeah, you've got that open point now. And then the other type, of course we've got, they're called US cells or underslung links. And then we've got our ABSs, which are air brake switches. And they're the ones with the handles. Um, you unlock those and you, and you can open the air. And they're usually what, uh, a, um, an open point, what we call an open point, because if you don't know the, the way the feeders work is it leaves one distribution breaker at the zone sub. It goes out on the poles and wires along the top, the top set of wires is, is the HV and it goes out and, you know, along the way it gets fed into pole mounted transformers, which then produce the LV. It goes out on the pole. But it'll, it'll, it'll get to a point where it's sort of halfway out through the neighborhood and then it'll come back again and go to another breaker. And in between, like, you know, further out in the network, there's, there's that air brake switch in between those two feeders. So the two feeders have an open point where they can be joined if they need to, or it's permanently open.

Dave Jones: Okay. Right.

Chris Gammell: It's like called a ring feed.

Dave Jones: Oh yes. Yeah, exactly. Um, houses, houses can actually be wired. Well, I don't know if they can be wired like that in New South Wales in, in the UK. Is it that, that does a ring? We use a radial, we use a radial system, which goes out from the one point, but you can actually have a ring.

Chris Gammell: Yeah. Not, not all of our distribution networks like that, but, um, you know, there's still lots of radial feeders, but what's cool about that is you can close that open point, which will bond both of those feeders. And then you move somewhere else and you open, um, you open another point. And so you've moved that open point now, and then you go back to where you were before. And now you can open up that other one. And now you've got an isolated section in between.

Dave Jones: Right. Does that sort of make sense? Nice. Yeah. Yeah. Totally. I can actually visualize that.

Chris Gammell: Two isolated points in it. Yeah. So, so initially for the day of switching, you'll get there, you'll call control, get on the switching plan. Everyone's ready to go. You'll close that open point and bond the two feeders together. Then you'll move down the road somewhere and open up another open point. And then from that open point, that'll probably be one of your isolations, one side of your work site. Then you'll move back, you know, through your work site to where you need to go and then open up the next, next one. And now you've got your isolations, your two isolations. But then either side of that still powered up and still back to the two breakers at the zone side.

Dave Jones: Yeah, because you want to minimize the number of people that are without power, right? Yeah, disrupt the dots, right. So you want to try and choose the optimum area to shut down. So how do you do that from like a mapping point of view? Oh, we've got a lot of systems, yeah. It's digital now. It's digital now.

Chris Gammell: And yeah, it's all well mapped. I mean, there's everything you want. There's all the paper maps, but there's also all the digital mapping as well.

Dave Jones: Right. And so can the app, so does the app, like if, can the app, is it smart? Can it tell you like, okay, we've got a fault here. Okay, go over to this pole over here and break that and break this one over here. And that minimizes the area that's out?

Chris Gammell: As a switcher, it's up to you to understand the network. And the switching plans for like what we call like a programmed interruption or, you know, an outage that we know we're going to have. Those switching steps are written down and they're passed through a chain of responsibility. And two or three people will look at them before it gets to the control room. And so they'll make sure that the switching steps are correct. You know, you do a close open here. You do an open at this air brake. You pull some underslungs here. You test an earth. The poles you're working on are the poles inside this isolation and so on. So that's all done fairly well. But as for faults in the field, well, that's sort of...

Dave Jones: You have to, yeah.

Chris Gammell: You have to use your best judgment. You might drive along and see what the cause is. It might have been called in. The customers are very good at calling stuff in. The breakers themselves, some of the relays, they actually can look down the line. And I think they use what's called a MOW diagram. It's an expectation of the resistance, the impedance of the feeder for a given length and load. Right.

Dave Jones: And when a fault... So they can impedance test the line somehow, sort of like transmission line impedance test, pulse test or something.

Chris Gammell: Yeah, like an echo... What's it called? Time domain reflectometry. You know? But mostly it's the fault data coming out of the relay will sometimes give you a distance. So the distance has been calculated for that feeder under normal conditions. And so a given fault at anywhere along that feeder will produce a certain current. And when that current does come from a fault, you can now say, oh, it must be this distance away. It's probably a face-to-face fault at this distance. And then, you know, the control room can give you a rough idea. You can look at your map and say, oh, that's on such and such road. Let's head out there and have a look. Very into it.

Dave Jones: Like, how do you do load shedding and stuff like that?

Chris Gammell: There's some automated load shedding to prevent, like, a transform. Like, if you knew that the load from the network was going to rise so much that it would eventually, the transform would trip from overcurrent, you'd obviously want to de-energize some of those loads so you didn't get to that point because there's no point knocking everyone off when you just want to.

Dave Jones: Yeah, yeah, right.

Chris Gammell: You know, so they do have some sort of anti-cascade, I guess you'd call it. They do have some load shedding. And it's, you know, they prioritize the feeders, essentially. So, you know, the hospitals and so on are on for the longest.

Dave Jones: They would get the priority. And there is apparently some new smart solar inverters that you guys can control. You guys can switch them off remotely.

Chris Gammell: The retail section was taken away. We don't do the retail anymore. And so a lot of the metering and that sort of stuff is sort of independent now. And they're the ones coming up with the ideas of, you know, the different load balancing and the pay per time a day use models and all this sort of stuff.

Dave Jones: And there's rumors around that you can adjust the frequency and or the voltage on the line to then will automatically disconnect the solar inverters. Because all solar inverters are programmed if they meet the, not only the Australian standard, but individual state standards, I believe, for voltage and frequency limits. And if the grid's outside that voltage limit, they'll shut off. And you guys can sort of tweak it. That's the rumor that's going around.

Chris Gammell: They can't per se tweak the voltage. The transformers, it's funny. The transformers, when I first started working, I thought there should have been more electronics in the transformers. There should be more smart. Right, no, there's none.

Dave Jones: Is there, right?

Chris Gammell: There's none. And you know what? After seeing a lot of them get hit, yeah, a lot of them get hit by lightning and or, you know, storms and that. I understand because they can just send them back to the factory, drain them out, clean the coils up and they're back in service.

Dave Jones: Right.

Chris Gammell: You know, oil and steel.

Dave Jones: How often do you get a transformer fire? Is that common? No, not very often.

Chris Gammell: It's actually, yeah, it is. And that's why the times that we have tried to use smarts that they might have. So they have a maximum demand indicator on a lot of these transformers and we read it once a year. And it just shows the maximum amperage that the transformer got to.

Dave Jones: Oh, got it. So it's just a peak indicator. Okay.

Chris Gammell: Yeah, it's a peak indicator and we just write it down once or twice a year. But we've tried to make versions that are electronic and report back via modem. And of course, you know, they just, sometimes they just can't handle being in the Aussie sun, you know, getting picked on by cockatoos and lightning strikes and that. Yeah.

Dave Jones: Smart electronics than you would in your dumb ass transformers. That's right.

Chris Gammell: But our zone subs have gotten more modern. We've gone to Ethernet now for a lot of them. Ethernet connected relays. And we've also gone to SF6 gas. So that's the other thing. Breakers are incredibly, because of the high voltage, an arc can be, you know, 5,000, 10,000 degrees, you know, surface of the sun's only 5,000.

Dave Jones: Oh yeah, surface of the sun temperature. Yeah, it'll melt everything.

Chris Gammell: Yeah, and so it melts everything, burns the contacts, you know. So we don't want arcing in general. But when the breaker opens, there's going to be some arcing. Because it's pulling two contacts that are energised apart. So there's a number of ways to prevent that. You can blow the arc out with compressed air. That's sort of an old method, but that's quite loud. And the compressors have to run for a bit, so they can't fire multiple times. You know, they have to wait 10 minutes while the compressor fills back up. There's the oil field breakers, and the oil will quench the arc. Then you've got arc shoots. They're like interleaves or sort of steel sheets with a little bit of a gap between them. And the arc magnetises those sheets, which then draws the arc in.

Dave Jones: Interesting.

Chris Gammell: Arc shoots, they're called, yeah. Yeah. And then the latest ones are SF6, sulphur hexafluoride. And that gas does not like to conduct at all. And so you can put it under high pressure, and you can make the bus bars, what in the past might have been the bus bars, might have been two metres apart. Now you can put them, you know, 100 mil apart. Right.

Dave Jones: But if they blow, then you've got to go in and recharge that SF6 gas, do you? Yeah, that's right.

Chris Gammell: But they have, you know, of course they've got pressure sensors in them. They're watching everything. But they're also extremely low maintenance as well compared to the oil lines. Yeah.

Dave Jones: Right. What is the, speaking of maintenance, what is the most maintained thing on the power lines? What, you know, like the suburban? The poles.

Chris Gammell: You know, the poles? The poles. Yeah, once every three or four or five years, each pole gets looked at and drilled and tapped and hit with a hammer and checked over.

Dave Jones: Oh, okay. So the physical structure of the pole. Yeah. The poles and the cross arms. The actual, right, the actual dead tree.

Chris Gammell: Yeah. That it's all hanging on. Yeah, that it's all hanging on. Right. Yep. And now the insulators will crack.

Dave Jones: I guess that's a plus point. Right. And the ceramic insulators will crack, right? Is that just a manufacturing thing? Heat? Oh, just the age of them too.

Chris Gammell: We've moved away from ceramics now to polymeric. They're kind of like a silicon, some of them. They're all sort of different.

Dave Jones: Okay.

Chris Gammell: You know, because wires can, you know, or conductors, they can either terminate at the pole or pass overhead. If they pass overhead, they're on pins. But if they terminate on the pole, that's when they'll hang off the polymeric or the thimble insulators, as we call them. A pair of dead ends. They're like a spirally wound piece of metal that grips the conductor and then bonds over the top. But there's a lot of different gear out there that you'll see. But they're moving towards, as you know, because you can't just trial things wholesale. You don't want problems, you know. No, exactly. You want your roll stuff out. You want it to last. Because most of this equipment, once it's installed, it's in there for 10, 15, 20, 30 years.

Dave Jones: Right. Yep. It's crazy.

Chris Gammell: Yeah.

Dave Jones: Where would the cost, I mean, this is probably company confidential, but where is the biggest cost base? Is it generation? Is it transmission? Is it maintenance? Is it personnel?

Chris Gammell: Is it? We probably don't pay for generation because the electrical energy is sold by the retail side. So they're charging their customers and they're buying the electricity off the generator to do that, I guess. So for us, it's going to be, oh, I'm not sure. There's a fair bit in the vegetation maintenance space.

Dave Jones: Okay.

Chris Gammell: Keeping trees clear of wires.

Dave Jones: Lopping trees and stuff like that. Do you guys just call in any tree lopper or do you guys have your own specialized tree loppers?

Chris Gammell: Yeah, we have. We usually set up some contracts with them and, you know, we have a couple of different major companies that look after us and trim the network. You know, customers, there are certain times that customers just can't really work on trees near the network, obviously, because it's just highly unsafe. And so, you know, there's certain work there that we have to do, you know, for the customers, for the councils and so on. So, yeah, we have an envelope. It's a set of clearances that the trees need to stay outside of. And so there's a, you know, they trim them back with a little bit of a regrowth factor and then trim them, you know, annually, semi-annually every couple of years, depending on the area. But, yeah, cross arms, you know, they used to be timber. Now we're getting, you know, ones that we've trialed metal ones. We've trialed composite ones. Yeah, we've trialed every kind of thing. There's metal poles, concrete poles, timber poles, composite poles. And they all have their sort of benefits and disadvantages.

Dave Jones: Power factor correction.

Chris Gammell: Ah, yes.

Dave Jones: How much of that is on the network? Like how many and what types and where?

Chris Gammell: From our point of view, we don't have a lot of it. The, we, well, we sort of do. If you have a load over a certain amount, it's up to you to make sure that you have power factor correction in the building.

Dave Jones: Right. So if you're a giant factory with massive motors going, you have to install, legally you have to install your own.

Chris Gammell: Well, you'll be, you'll get charged more from the retailer.

Dave Jones: Oh, you get charged a lot more. Okay.

Chris Gammell: Based on your power factor. So, you know, for us home punters, we don't, we don't get charged power factor. No. That's right. And it's not even monitored in the meter in general. The electronic ones probably can, but.

Dave Jones: The newer smart ones do, I think. But we still don't pay for it. Yeah.

Chris Gammell: But the bigger guys do. And so they'll have a power factor correction cubicle, which just, I think it's just a cap, cap bank that switches in and out. But where, where we do, where they sometimes have it in an infrastructure sense, like inside a zone sub is there might be a high voltage customer that'll have a feeder that goes to say an aluminum smelter. Or a glass smelter. Yes, of course.

Dave Jones: Massive power demand.

Chris Gammell: They, they dip these electrodes, 11 KV electrodes directly into the bauxite. And, you know, just the power that it draws in a split second from, from the system is crazy. So they have to design, I think they call it a reactor. It's basically a big coil choke. I think, you know, that kind of smooths the power.

Speaker ?: I was going to ask.

Chris Gammell: Yeah.

Dave Jones: Because most power factor correction would be capacitive, right? I was going to talk about, are there any inductive power correction? Yeah, look, I'm not sure, but. That would be a case where they use it, right?

Chris Gammell: Yeah. Yeah. It's by, it would be by exception, you know, for special projects. But I think, you know, the average, you know, home device these days, it's pretty good. Like, you know, as an electrician, I remember working as an apprentice and definitely if, you know, be pulling a fluorescent light apart to fix it for the customer and the capacitor's blown. And it's just in parallel or whatever, you just pull it out, you know, the power factor correction, away you go. But you don't do that in an office. You don't buy the non-power factor corrected lights when you've got a thousand of them to put up in a.

Dave Jones: Yeah, exactly.

Chris Gammell: You know, you'll be paying for it.

Dave Jones: Yeah. So the big question, big question, everyone wants to know, of course, is what meter do you guys use? If you're a linesman, if you're out there, out in the field, which meter is there? Are there approved meters?

Chris Gammell: Yeah, oh, absolutely. We used to use the T140. It was a fluke and it's a style with a probe at one end. So it's not like a traditional rotary dial type or anything like that or push button. It's a single. Well, they used to use test lamps, Dave.

Dave Jones: Oh, yeah. A pair of lamps. Yeah, no worries.

Chris Gammell: Obviously, with all our testing, we're pretty smart around it. We test before and after. So you make sure your meter is working correctly. All right. So it's actually reading. Then you do your test and you prove your isolation. Then you test your meter again. So even with a set of test lamps, theoretically, you shouldn't have a problem. But if you fail to test again and you've got a blown bulb in your test lamps, then it wasn't going to pick up your test properly. Exactly. So we moved away from that. But it's a similar thing. It has the two probes because you've got to imagine the guy might be on a platform or hanging off a ladder in his belt. And he's reaching above his head. And he's going from phase to phase. And this is only LV. And so it's a Fluke T140.

Dave Jones: I've got it open right here. And for those curious, it's a Cat 4, only 600 volts. Cat 4, 600 volts. Cat 3, 690 volts. So it's not as good as it gets. You can actually get Cat 4,000 volts these days. So it's the form factor. It's the form factor. It's the form factor.

Chris Gammell: We have – I'm going to get in trouble because the guys are going to roast me. I'm sure we've moved away from that one now. We've moved again. Okay. But I know, for example, in the Zone subs, they use a higher Cat rated one again.

Dave Jones: Right.

Chris Gammell: Because you do have the potentials there for, you know, 11 kV. I wouldn't know. But I can get back to you.

Dave Jones: Yeah. Get back to me, please. I'll put it in the comments.

Chris Gammell: When we do the high voltage, there's special gear there. We have what's called a Modiwark or Modiwark. It's the brand. And it's a – it comes with a little hand test. And it's a feel.

Dave Jones: How do you pronounce that? Modi?

Chris Gammell: M-O-D-I-W-A-R-K? Maybe Modiwark? Modiwark kit.

Dave Jones: Okay. Yeah.

Chris Gammell: So, you know, there's a lot of brands. Oh, I see. Yeah. Some of them are non-contact testers because, you know, with high voltage ABC bundled, aerial bundle conductor, it's obviously insulated with XLPE. You can't pierce it with your tester. So you need to, you know, just check on the outside of the cable with a field tester. A lot like those voltage pens, which, by the way, we do not use those voltage pens.

Dave Jones: No. Well, this is basically a high voltage professional version of those voltage pens, right? So it is a non-contact tester.

Chris Gammell: Yep. And you push that up on the pole because, obviously, you can't get close enough on the stick, sorry, because, obviously, you're not going to be within clearances or work on high voltage while it's energized. Right. So you test from the ground generally or in a bucket, or EWP, sorry. You might test from in there nearby, sort of push it near the mains. You'll test each of the phases and then you'll test the meter itself. It comes with a little handheld thing that you push a button and it creates a field and you hold it on there and it beeps. Interesting.

Dave Jones: Yeah. Specialized bit of kit.

Chris Gammell: Yeah, of course. It is. We've got a few of those. We've got clamp tong amateurs as well that, you know, you can do 1,200 amps at, you know, 132 kV.

Dave Jones: Yeah, right. Yeah, yeah.

Chris Gammell: Push them up.

Dave Jones: But I assume you wouldn't. Would you use a current clamp that often or is that?

Chris Gammell: Not really. In the zone subs when you're doing, they're called protection technicians. I know you get a lot of people listening. So if there's any young budding engineers out there, have a look at, you know, employment in this field because it can be really fascinating. But we do a lot of current measurement in the zone subs because all of the protection equipment, the breakers and everything, that's what they use to trip. They even have what we call differential protection schemes, which is where you ship a portion of the current you're sending on an overhead pilot wire to the far end. Oh, really? Yeah. And that current holds a relay open. And the moment that current stops, that relay drops. So it's like, I've sent you this. If you don't receive it, you need to trip. Yeah. Yeah. And that was very old school. And that's really just a set of CTs that then, you know, send that current over a pilot wire to the far end relay.

Dave Jones: Nowadays, it'd be done with comms, right? It is. And it's optic fibre now.

Chris Gammell: Yep. Right.

Dave Jones: Multi-stream optic fibre. Newfangled stuff. Yeah. Yeah. Boo.

Chris Gammell: We've used radio a little bit. Look, nothing beats the physicality. All the breakers and that, they're all physically wired. Every single one of them, just about. They were actually a bit shy when they put their first sort of Ethernet style.

Dave Jones: Yeah, I bet.

Chris Gammell: They're a bit nervous about this because it's a bit newfangled for us, you know.

Dave Jones: Yeah, exactly.

Chris Gammell: Liability's important, but protection is, you know, paramount. You know, safety's a rule. Do you know the rule? Is it I-Z, I-B, I-N? I-Z's got to be greater than I-B. He's got to be greater than I. It's in the AS3000, which is our electrical safety. That's the electrical rules in Australia for an electrician.

Dave Jones: Oh, okay. Yep.

Chris Gammell: I-Z is the impedance of the cable.

Dave Jones: Yep.

Chris Gammell: I-B is the breaker current. And I-N is your expected normal load. I think this is right. So, you know, the cable's got to have the highest current carrying capacity. And then the breaker and then the load. So the breaker should trip before the cable burns.

Dave Jones: Correct. That's the whole point.

Chris Gammell: That's the whole. It says in the front, it's the first paragraph, I think.

Dave Jones: Right, is it? I see this is something that I don't generally know. But I do know that the circuit breaker in your house is not designed to protect your products that you plug in. It's designed to protect the wiring from catching on fire.

Chris Gammell: You've got a 20-amp cable. You can't put anything bigger than, you know, an 18 or 19 or 20-amp breaker. I-N could be higher. You can draw 40 amps, but you're just going to trip your breaker all the time and it's going to be a nuisance. But, yeah, I-Z's got to be bigger than I-B.

Dave Jones: I've never heard it explained like that before. But, yes, that makes sense.

Chris Gammell: I think it's in, when you train as an electrician, I think it's in that AS3000, the Australian standard. And that's our wiring standards for domestic dwellings. There's another one that people might enjoy looking up. And that is the Australian, the service rules. And the service rules, the New South Wales service rules, they're the ones that sort of, it's in between your house and the street. You know, what cable you should run from your board out to the street. You know, what size conduit. Next level up. How high your service mains need to be above a driveway. How high above an awning. What size conductor. Got it. That's it. New South Wales service and installation rules.

Dave Jones: There you go.

Chris Gammell: Yeah. It's another document.

Dave Jones: Fun bedtime reading. Yeah. This is great. Oh, thank you very much, Toby. Our amp power is unfortunately up. We can talk about this interesting stuff all day. But that flew by. That is great stuff. Which we just don't, because we have no idea about this. You know, just as a general, you know, engineering nerd. We just, no, we just take it for granted.

Chris Gammell: Yeah, we use the power that comes in to the house and that's it. We know there's generators out there. We know there's zone subs, but there is quite a bit of engineering that goes into it. There really is.

Dave Jones: Yeah. Fantastic. I'd love to get like a tour of one one day, you know. Let me see.

Chris Gammell: Yeah. I'm not sure. That's probably something we've never really done. But I know there's some great zone subs that you'd really be fascinated by. And there's a lot of associated systems too that we didn't even talk about. Like the frequency injection for the hot water systems, you know.

Dave Jones: Oh, yes, of course. The street lighting systems. Yeah, yeah.

Chris Gammell: You know, there's a lot of stuff in those zone subs that you don't even see. And it's more electronics focused too.

Dave Jones: Yes, which is basically comms over power line for those that don't know. They send like the hot water thing was a one or two kilohertz signal. Yeah, that's right. Which was actually modulated over the power line.

Chris Gammell: Sometimes you'll hear it. If you've got a fan running. Yes. You'll sometimes hear it in the motor windings.

Dave Jones: Yep. Or you'll see it on your oscilloscope. I see it pop up in the lab all the bloody time. I'm taking some sort of mains measurement. And, you know, there's my 50 hertz waveform. And that pops this little modulated bloody sine wave on top of it.

Chris Gammell: Yeah, up to seven volts or something sometimes too. Yeah. Yeah. It just sticks out like a dog's eye leg. You can see the injection. Yeah. At the other end, there's a big cabinet that controls it. But then to inject it, there's these toroidal transformers and all this crazy gear. And it just looks incredible just to inject it on. Because you've got to inject it onto the 11 kV.

Dave Jones: And it's a very low impedance line you're injecting onto as well. It's like, yeah, it's got to be grunty to.

Chris Gammell: Yeah. Yeah.

Dave Jones: Wow. Fascinating stuff. All right. Well, thank you very much, Toby. You're welcome. Where can people catch you?

Chris Gammell: Where can people follow you?

Dave Jones: Are you madly online? You do the Twitters?

Chris Gammell: I do have a website and a bit of a YouTube channel. But if you want to chat palons or ask any further questions, you know, that post I put up on your blog.

Dave Jones: The forum. Yes. You put an awesome post up on the EV blog forum. I'll link it in. That's where you offered to get a whole bunch of detail in there. Yeah, it's just people who've got questions about how it works. And offered if people have questions. Yeah. Yeah, sure. Yeah, we'll definitely link that one in. Awesome. Thanks, Toby. We'll have to catch up again in person soon. Yep. Yep. Great. Cool. Thanks, mate. Catch you next time.

Speaker ?: All right.

Chris Gammell: Cheers, mate. Bye.

Chris Gammell: Bye.

Speaker ?: Bye. Thank you.