Electric Shock with Peter Stepien

Electricity in mines is a very concerning hazard.  And while there have not been any fatalities in Australian mines due to electrocution in well over 30 years, this does not mean engineers are not working on it.

Peter Stepien spoke to Mel & Dom about his concern that engineers must stay vigilant with evolving technology, specifically currently with variable speed drives in mines. 

Extra discussions during the episode

This is a “close” copy of the words that were spoken during the Podcast, Season 5 Episode 10

It is not 100% accurate.
The guest was Peter Stepien

INTRO

Mel: [00:00:00] Welcome to season five, episode 10 of engineering heroes, a podcast that is presenting the new Dawn of engineering challenges. My name is Melanie and my co-host and our podcasts resident engineer is Dominic.

[00:00:14] Dom: [00:00:14] Our guest received his degree in computer engineering from the university of Newcastle and a PhD degree from the university of Sydney.

[00:00:21] He’s current position is as a principal engineer at ResTech, taking a leadership role in providing consultancy services to industry and designing electronic equipment.

[00:00:29]He has carried yet numerous investigations into earth fault, limited power systems, including electric shock indices, and the use of VSDs covering the effect of circulating currents, touch potential and the impact on protection devices.

[00:00:42]He’s work at restech resulted in the patent for the detection of leakage of fault currents from equipment in electrical power system and associated products.

[00:00:51]Our guest is a registered chartered engineer, fellow of Engineer’s Australia and senior member of the IEEE.

[00:00:57]He also holds the position of conjoint senior lecturer at the university of Newcastle.

[00:01:02] Joining us today on engineering heroes is Dr. Peter Stepien.

[00:01:08]Mel: [00:01:08] Peter’s father was a carpenter. He used to help his dad design and even make things. He saw his dad build furniture and even houses. And he was actually helping his dad build a house that they were going to live in when electrician came to wire up the house. And Peter found himself intrigued by all the wiring, which led him into electronics and then computers.

INTERVIEW

Peter: [00:01:31] And incidentally my brother went down the path of being electrician. So I think we’re both influenced by my father’s work

[00:01:38]Mel: [00:01:38] Oh, the electricity electrician, you shouldn’t seem to impact. So what was the first project that you worked on as an engineer?

[00:01:49] Peter: [00:01:49] So the first project that I worked on was actually as an  undergraduate engineer. So whilst doing my degree program, we had to do industrial experience. And I actually worked at  Eraring Power station, which is where I lived at the time. And I think I was probably one of the only people who actually worked there that lived in Eraring, cause Eraring is a very small town. It’s not a very big town. And  the work that I did there was on the Eraring power station simulator, it was basically a simulator that was used to train operators  to control the power station. As you can imagine, a power station is a very large, complex piece of machinery.

[00:02:26]And at the time the power station was controlled from two control rooms. Each control room controlled two units. So there’s four units all together. And then the right power station simulator. Basically it was a simulation of half a control room, which controlled one unit. And the task that I was given whilst working there was to actually model the auxiliary cooling water system. Which is clean water system that cools certain parts of the power station that are critical to the functioning of the power station. So it was a great experience, cause it allowed me to program in Fortran. Allowed me to interact with the engineers who were there. At the time Toshiba were also commissioning  the simulators.

[00:03:06] So we had engineers from, from Japan there. So I was able to talk with them as well and gain from their experience. As well as from the engineers at the power station itself, which at the time was owned by the Electricity Commission of New South Wales. So I was very fortunate to be able  to work there.

[00:03:22] Dom: [00:03:22] And from the sounds of things, if you’re working the cooling water system, it wouldn’t have just been electrical would, or you would have been dealing with all disciplines, particularly regards to mechanical and hydraulic, and  services engineers.

[00:03:33] Is that the case?

[00:03:34]Peter: [00:03:34] That’s absolutely right. And in fact it was actually a good introduction to my career in general and probably actually all engineer’s careers. Whilst we tend to focus on one discipline while we’re studying and training as an engineer, during our career we actually cover a lot of different types of disciplines.

[00:03:50]Obviously too, since we’re not trained in certain areas, we have to ask others for some information. But for example, the auxiliary cooling water system, I had to model a circuit that included water flowing through valves, through pumps. So I had to get an appreciation for the the mathematical models that describe how those pumps work.

[00:04:08] So whilst it was still like in electrical or computer engineering type discipline, with regard to having to program in Fortran to actually create the model. It did require a broader knowledge of other engineering disciplines at the same time.

[00:04:22]Mel: [00:04:22] So that was a while ago now. So whereabouts are you working nowadays?

[00:04:28]Peter: [00:04:28] So now I’m actually working for a company called ResTech which is partly owned by Ampcontrol and partly owned by University of Newcastle.

[00:04:35]Mel: [00:04:35] So what sort of things do you do for ampcontrol or Restech?

[00:04:39]Peter: [00:04:39] So a lot of my current work is to do with electrical safety. And in particular, looking at touch potentials in equipment used in the mining industry, particularly underground coal mine. It’s a very arduous environment. It’s very wet. We have equipment down there, that’s  electrically powered.

[00:04:57] And of course we want to make sure that people who are working in that environment are not going to get electric shock when they’re working on that equipment. And there has been tried and proven ways of doing electrical system to ensure that that doesn’t actually happen. However over the years, things have progressed, the voltages used  have increased.

[00:05:14]And we’ve also are using now our variable speed drives to control motors. And that is actually it’s a bit of a blessing in disguise, because it actually makes it easier to control motors at the same time, it creates an additional hazard that wasn’t there previously.

[00:05:30] So a lot of my work is looking at the effects of variable speed drives used in the mining environment and how we can actually control touch potential so people don’t get electrocuted.

[00:05:40]Mel: [00:05:40] And do many people get electrocuted in mines?

[00:05:45]Peter: [00:05:45] No, in fact, the mining industry is very safe with regard to electricity. In fact, there hasn’t been a fatal electrocution  for must be now more than 30 years, that’s extremely safe.

[00:05:56]Mel: [00:05:56] You’re doing a good job then.

[00:05:58]Peter: [00:05:58] Well, and I guess this, this is where we want to make sure that when new technology gets introduced into mines, like variable speed drives, that we make sure that we do identify hazards before they become a problem. So whilst  the methods that are used  at the moment that are in the current standards worked well for the existing equipment. As we introduce new equipment into the mines, we have to make sure that we don’t introduce hazards as well.

[00:06:22] So as part of my work is, is trying to understand what those hazards are and make sure that that doesn’t actually become a problem. And this basically involves modeling  these electrical systems to ensure that we aren’t generating touch potentials, that might electrocute  somebody and also coming up with solutions where we might have, for example, a new protection device that can be used in the electrical system that will make the the system safer.

[00:07:29]Mel: [00:07:29] We will be right back with more from Peter as he delves into his hot topic around electric shocks in the mining industry.

HOT TOPIC

[00:07:37]Peter: [00:07:37] Well, as far as the challenges in my field goes with regard to electrical safety in mines, I guess to me there’s still some things that can be done with variable speed drives to make them safer. And in fact, this is some of the ongoing research that’s happening between ResTech and the university of Newcastle. We’re actually looking at ways of designing the variable speed drives so the issue with them doesn’t actually occur in the first place. Because one of the main issues with variable speed drives is that they want to drive a high frequency current back through the earth system.

[00:08:12] And generally the earthing system is used to ensure that any metallic parts of the equipment remain at earth potential. However with variable speed drives, we actually do have a high-frequency current flowing through these paths, which in the past would never didn’t actually happen. And this, this is one of the things that for me, it’s an outstanding issue.

[00:08:33] And in fact, if we can actually eliminate this high-frequency current flowing through the earth path we’ve actually solved     a  longstanding issue with variable speed drives.

[00:08:43] Dom: [00:08:43] Do you find that it’s easy to get engagement with the manufacturers in regards to doing these studies and, and looking into these issues.

[00:08:50]Peter: [00:08:50] Yes. I find that both the  OEMs and the end customers or the end users are very much on board with the safety. In fact the mining regulators in the various States they’re very much committed to ensuring that we have a safe working environment.

[00:09:05] And I guess the fact that we haven’t had any fatal electrocutions  in the mining for such a long period of time justifies to that. So if, for example, I wanted to do a study and I’ll need some information to be able to do that study, I find that everybody’s actually quite willing to, to help me in doing so. Which is really great to see, and it’s really nice to work in an industry where everybody is so committed to safety

[00:09:27] Mel: [00:09:27] Can I just clarify.

[00:09:28] So you said something that in my head, it sounded like you said that the electricity to these plant is the big problem in the mines. And if you could fix that, that would make everything better. Is that, is that, or did I completely misunderstood something?

[00:09:45]Explain to me, what a variable speed. What was it called?

[00:09:49] Dom: [00:09:49] A variable speed drive.

[00:09:50] Mel: [00:09:50] Explain to me what a variable speed drive is again.

[00:09:53]Peter: [00:09:53] I’ll try explaining it again. Maybe. Yeah. Variable speed drives the way they operate. They basically take in the normal, power that we would normally reticulate as an input and they generate an output, which is variable frequency and variable voltage. And that basically allows you to connect a motor to the variable speed drive and have the motor run at different speeds.

[00:10:15] So, as an example a escalator in shopping centres these days will tend to slow down, speed up depending upon whether somebody is there or not. So, if you see, for example, if nobody is using the escalator, it’ll just be crawling along slowly just to let people would know that this is actually working, but you know, there’s nobody on it.

[00:10:32] So why operator it at speed, and when somebody comes close to it, then it speeds up. So they can traverse the the escalator. Similar technology is used in the mining industry as well to control various pieces of plant. And similarly, for example electric vehicles, we have a similar sort of system to where electric cars, where we have a system where we have basically a variable speed drive that controls the power to the wheels.

[00:10:57]And in the mining industry, they’re also use electric vehicles. But what they tend to do is they tend to have one or vehicles that are connected by very long trailing cables. And this can be cables, which can be, you know, a hundred, 200 meters long that basically are reeled on a reel on the actual vehicle itself.

[00:11:14] And these then move through the mine,  powered effectively by a long extension cord. And this is one of the reasons why managing touch potentials, which is basically the voltage that you might feel if you were to touch a piece of plant difficult in the mining environment, because you have effectively, no local earth to the machine. The earth is only provided by the trailing cable itself. So we use a technique which is basically an earth-fault limited system, which means that if you do get an electrical fault between one of the base conductors and earth the current that flows is limited to a small amount, typically five amps or two aps. Whereas in a house, if you were to connect the power to earth you’ve actually got a very large count that flows.

Mel: [00:11:55] So there’s this big problem about variable speed drives in mines and having like a 200 meter extension cord, I mean, that’s just crazy. I don’t even like going from the garage to the front of the house. So I kind imagine how bad it would be in a mine. So what’s something that engineers can do about this. What are engineers doing about this?

[00:12:12]Peter: [00:12:12] to manage touch potentials for equipment that’s powered by trailing cables, there’s a whole suite of devices that are working together. And in fact, these are described in an Australian standard, AS4871.1 and the devices that are used are described in AS2081.

[00:12:28] And basically the way we ensure that we don’t get hazardous touch potential on the equipment is to ensure that we actually have an earth conductor going from the supply. In other words, where the transformer is to the vehicle itself. So we actually actively monitor that earth conductor to ensure that it’s there and to ensure that it’s actually a low impedance. Say if for some reason that earth conductor was to break or become a high impedance, equipment would be actually powered off to ensure that we don’t get a hazardous touch potential. Now of course, if there is a fault on the machine itself and we do get current now flowing back through that earth path it’s limited now to five amps or two amps, and since we are monitoring that earth conductor, we know what the impedance is. Which means that we can then know what is the prospective touch potential it’s going to be. And the whole idea is that we wanted basically turn the power off if that touch potential is there for too long

[00:13:29] Mel: [00:13:29] Is this something you guys can already do, or is that what you’re saying is needing to be put in place or created?

[00:13:36]Peter: [00:13:36] So what I just described about, for managing touch potentials is what’s actually already done now for traditional equipment. Okay. Variable speed drives add an extra level of complexity to the protection scheme and the fact that you have this high frequency, current flowing all the time. Okay. So you need to make sure that that touch potential that’s caused by that high frequency current is not too large. And also when you do get an earth fault, as well as having the normal 50 Hertz current that flows, you also have the high frequency current that flows. You have to be able to manage that as well. And, and unfortunately the high frequency current wants to flow differently to what the low frequency current  flows.

[00:14:16] And this is due to cable capacitance or capacitance in the system. And this is what makes it a little bit more difficult. So this is why if we can create a variable speed drive that doesn’t generate these high-frequency earth currents we can actually make it a lot safer.

[00:14:33] Mel: [00:14:33] Yeah, no, it’s a good direction to be moving in.

[00:14:36]Dom: [00:14:36] So just in regards to the future of engineering, What are your thoughts in, in the way that engineering is tracking and what are your thoughts on the future of engineering?

[00:14:45]Peter: [00:14:45] Well, I think engineering is, is something that’s gonna continue on into the future. I don’t see any sort of  point in time when engineers won’t be required. To think about where we’ve got to now I think without Engineers, we wouldn’t necessarily be where we are at the moment.

[00:14:59]And whilst there might be some issues with how things are done in the past and possibly now, engineers are definitely, we’re very aware of you know, environmental factors and things like that. And, and it’s nice to sort of see  that the new technologies that are coming about that are actually addressing these things.

[00:15:15] And I mean, to me, it makes it a very exciting time as well, because. Whilst it’s nice to be able to design something based upon some traditional principles, we’re sort of in a, in a time now where things are changing quite a lot. So we have to actually be very innovative in what we do. In other words engineers today are designing things that weren’t designed 10 years ago.

[00:15:36]And in fact when I do designs now… things that I do now, are not the way they were done when I first graduated as well. Things  have progressed so far.

[00:15:44] Mel: [00:15:44] So quickly everything’s moving. And so what would you say to people just starting out in engineering?

[00:15:49]Peter: [00:15:49] well, I, I guess I like to find out whether  they’re really keen engineer. So whether they sort of, I’m thinking that maybe they might want to do engineer. So if they’re really keen engineers I like to sort of find out, what are they really keen about? And try and sort of encourage them in, into areas that, you know, might be able to build upon that.

[00:16:07]So definitely it’s definitely encouragement for them. And those who maybe aren’t so as determined maybe as, as others that maybe came across engineering as a possible afterthought, you know, I’d like to sort of maybe try and encourage them to continue down that path because obviously if they’ve looked at a wide range of things they might do, and engineering did come up, there must be something in there  that they like. And, and to me, I’m an engineering is a very rewarding career because at the end of the day, you actually build something, you actually design something that some, some end result that you can actually look at.

[00:16:38]And whilst I do like science, I see engineering as being an applied science where you can take the knowledge of how things actually work and put them together to something that actually does work.

[00:16:47] Dom: [00:16:47] It’s, it’s nice to have that thought that you can leave your mark in regards to you know, your, your place in society.  And we’ve talked about it before, where there’s so many engineers to walk around to their poor children. That’s like, Oh, I did that. I worked on that. And you know, I was involved in that and you know, then the story behind it as to why it is the way it is and how all the things that you had to overcome.

[00:17:08]Peter: [00:17:08] So I guess the only thing in a field like electrical engineering or electrical and computer engineering is that things progress so fast that things that you designed in the past, become obsolete very quickly.

[00:17:21]And in fact, I’ve got a shelf here of things that I’ve worked in the past that were cutting edge. I did the job well and and, and the customers were very happy with it that are now basically obsolete sitting on the shelf. Even to the extent where I worked on some equipment at BHP steelworks in Newcastle. That solved a problem. And it worked really well. But of course the steelworks closed down and that equipment is  no longer required.

[00:17:46] So it’s actually quite transitory where, whereas for example I envy the civil engineers that for example, build a bridge and that bridge is going to be there for a long time. Something that I might design now you know, the technology progresses so fast, it might not be around in, you know, in 10, 20 years time.

[00:18:01] Mel: [00:18:01] That’s actually, that’s very true. I mean, even when you were saying your first job, you were coding in Fortran,

[00:18:06] Dom: [00:18:06] was it.

[00:18:10]Peter: [00:18:10] Code… yes, yeah. And in fact, the Eraring power station, simulator that I worked on is no longer there anymore because basically, that technology, that simulator was designed in, which is the same as the original control room in the power station it’s very old technology.

[00:18:24]If I was to sit down and describe what this actually used, you’d be, you’d be quite amazed. However, now everything’s been replaced by modern computers. And in fact, the two control rooms in the power station has been reduced to one control room that controls all four units. It’s all basically, you know flat panel screens that display information, whereas in the past, It was these beautiful mimic panels that basically had every valve, every connection, all laid out on this wall. So the wall in the control room was basically the power station.

[00:18:53] So I was actually quite nice and I really enjoyed that. Of course, that’s just not how it’s done anymore now.

[00:18:59] Dom: [00:18:59] Yeah, we’ve definitely come a long way from there. That’s fine. And that segues perfectly into  is there a piece of engineering that impresses you?

[00:19:07]Peter: [00:19:07] Well, I, I think for me, there’s a, there’s a few things. First of all, in my field of engineering the mobile phone has to be something that encapsulates all the things that I used to work on when I first graduated. And in fact, whilst I was a cadet for the Electricity Commission of New South Wales.

[00:19:22]When I worked at the at Newcastle University at the Center for Industrial Control Science (CICS) my work involved doing effectively embedded systems design, which is designing bits of intelligent equipment to do certain things. So this is like based around a microprocessor. And of course, things I did then, so different to the way things are done now.

[00:19:39] Basically then I would have to have a large board with 20 chips on there. Whereas now a mobile phone, everything’s integrated effectively onto one or two very large devices. So mobile phones to me is is really quite, quite nice.

[00:19:53]And things outside of my field. I mean, well, maybe not completely outside of my field, but I’m most impressed with aviation,  with aircraft.

[00:20:00]I love to fly and you know, the way that modern aircraft are  designed and built is really quite nice because it’s actually a multidisciplinary endeavor. And also it’s a safety critical system as well. These machines have to fly reliably and if they do fail, they have to fail safely.

[00:20:17]I remember when, I was thinking I might have still been at university. It might be after I graduated, I had an opportunity to actually sit in the cockpit of a 747 flying to New Zealand, which was absolutely amazing. You wouldn’t be able to do it, do it now, unfortunately,

[00:20:30] but yeah, but but back then they used to ask  children if they wanted to go to the cockpit and you know, me as an adult engineer, I put my hand up anyway and maybe they took pity on me.

[00:20:41] They put it that are now he’s an engineer better let him go up the front. It was a very, very good experience. And it was actually quite nice to see, you know, see all the systems in the cockpit as well.

[00:20:50]Mel: [00:20:50] Airplanes have been a real theme lately on the, on the show. We’ve had quite a few people that have really liked aeroplanes. So and just to finish up, is there an engineer that you admire?

[00:20:59]Peter: [00:20:59] So I probably don’t actually have one historical engineering figure. I mean, I do do like reading about all this historical people , engineers and scientists that basically paved the way to what we have now, but there are two engineers that probably influenced my life.

[00:21:15]And one is a Professor Graham Goodwin who Employed me in the Centre for Industrial Control Science (CISC) at the University of Newcastle. And the other one is a Peter Cockbain who was one of the founders of Ampcontrol which partially owns ResTech where I, where I currently work now.

[00:21:28]These two engineers are leaders in their field. And they’ve made their mark on the engineering landscape. And in fact, they’re still doing so. They’re both effectively are retired, but they’re both still working , Professor Goodwin at the University of  Newcastle and Peter Cockbain’s still involved with Ampcontrol.

[00:21:44]And coincidentally, whilst these two have employed me early in my career and now, I did actually meet both of them when I was in high school. My maths teacher encouraged me to enter a competition, which was at the time sponsored by AmpControl at the University of Newcastle, well actually was sponsored by Raelec-Scientechnic, which was part of that group.

[00:22:03]And I was fortunate enough to win a prize. So when I came to university to accept the prize I met both Professor Goodwin and Peter Cockbain there. So, and little did I know there as a, as a high school student, that these two would actually employ me.

[00:22:16] Mel: [00:22:16] Oh, you’re.

[00:22:18]Dom: [00:22:18] Did they remember you.

[00:22:19]Peter: [00:22:19] Oh definitely, yeap. They, they do and, in fact, I keep in contact with both of them still

[00:22:24] Dom: [00:22:24] That’s

[00:22:24] Mel: [00:22:24] amazing. Talk about people that have really impacted another person’s engineering and career from, for you from very much day one. So they are great people to end on. Thank you for bringing them to our

[00:22:38] Dom: [00:22:38] attention.

[00:22:42] Mel: [00:22:42] Thank you so much for joining us.

[00:22:43]Peter: [00:22:43] you’re very welcome.

[00:22:44]Mel: [00:22:44] Thank you for having, yeah, it’s been wonderful

[00:22:46] Dom: [00:22:46] chatting to you.

[00:22:47]Peter: [00:22:47] thank you very much.

OUTRO

And thank you for listening to another great episode of engineering heroes. As we present the new dawn of engineering challenges for engineers Australia. You can view our show notes or learn more about our podcast by visiting our website, www.engineeringheroes.com.au. 

If you enjoyed today’s show, all we ask you to do is go and tell someone seriously, it’s that easy either in person or write a review, just get the word out, that’s how you can support engineers everywhere.

We look forward to you joining us next week when we bring you in another interview with one of our engineering champions.