On the east edge of Mishawaka, Ind., there is a large electrical substation that remains where the Twin Branch coal-fired generating plant once stood. The plant was built in the 1920s next to the St. Joseph River hydroelectric plant. The power from the hydro plant could be used to bring the coal-fired plant online after a cold shutdown. The river also furnished water for the steam condensers. The environmentalists convinced the power company to switch from coal to oil. When the oil embargo hit, they were told to switch back to coal. Lacking a sense of humor, the owners had the plant dismantled in the late 1970s.
A few years ago, there was an explosion and fire in a transformer. It was one of those fires that they just let burn until all the oil used to cool the transformer had been consumed. Not every firefighter wants to rush into an area where 138,000V is the norm and start spraying water from a fire hose. Oil and water are not a good combination, even without the high voltage. I don’t remember if they tried foam. If they did, it didn’t work.
After watching the fire for a while, I wondered if removing the oil from the transformer would help. You need fuel, heat, and air to keep a fire going. I’m wondering if it would be feasible to have an underground tank connected to a drain on the transformer. Something as simple as a ball valve could be connected to a long linkage. This would allow the valve to be opened from a safe distance. It could also be motorized. Gravity would allow the oil to flow into the underground tank. The tank might need to be kept purged with an inert gas just to be safe.
I’ve heard about aircraft in trouble dumping their excess fuel before landing. You have to wonder where that fuel goes after being jettisoned. Jet fuel does not evaporate like gasoline. My hunch is that the fuel is jettisoned to aid firefighters in the event of a fire. If it works for aircraft, it might work for transformers. If the oil could be contained in the underground tank, that might aid in the cleanup. The less oil there is leaking out on to the ground, the better. Murphy says that if you are ready for the fire, it won’t happen.
I don't know if this system has ever been put into service, but it was apparently not at the Twin Branch fire.
This entry was submitted by Pete Ostapchuk and edited by Rob Spiegel.
Pete Ostapchuk was a radar operator on a Nike Hercules site in the Army, where he studied electronics through correspondence courses. He ended up in the electronics engineering department at CTS for eight years, where he worked on industrial automation projects. He also worked at Bayer for eight years in medical diagnostics R&D.
Tell us your experience in solving a knotty engineering problem. Send stories to Rob Spiegel for Sherlock Ohms.
I would like to know a bit more about the tranformer failure modes and then design safety features around the most common issues. Removing the fuel from the fire and keeping it away and safely held after an incident is a good idea.
My guess is that the incidence of this kind of failure are low enough that the insurance companies are willing to put up with it.
Recall that in the early part of the last century steam boilers were routinely used for heating apartment buildings. teh insurance companies eventually enforced the adoption of what would become ASME standards for boiler inspections and safety operations.
The same thing applies to the blowout preventers on oil drilling rigs like the one that failed on the BP rig in the gulf. the oil companies should have to obtain unsubsidized insurance on their operations and be held liable for uncapped (by the Feds) liabilities if they screw up. the blowout preventer manufacturers should have good designs, well tested and thorough inspection standards to insure their systems perform adequately.
Insurance costs can be a pretty effective way to force environmental responsibility.
Gee, the idea of an underground tank connected to the drain on the transformer seems obvious. Could there must be some good reason why it hasn't been done?
I don't know enough about the electric industry to say that it has not been done or proposed. If it has not been done, it might just be one of those things like surfing the internet while walking the dog. We never realized we just had to have the capability.
Even the pole transformers that feed your house have oil in them but it's not a big deal when one of them catches on fire. As the size increases, the scope of the issue goes from a nusance to a catostrophe.
If it hasn't been done, it could be an economic issue. How much would such an installation cost? How much would the property tax on such an installation cost each year? How often do the really big transformers catch on fire? Would there be any savings on insurance?
Maybe someone with the answers will respond. Pete O.
I agree, Chuck. It is surprising this safety featue has not be imagined earlier. While it would involve costs, the costs would be nothing compared to the value of ending a fire quickly.
I'm sure it would financially make more sence for disaster mitigation using 20/20 hindsight; however, when the capital of the design is being justified you don't know you're going to have a fire or how soon. There are several potential catastrophies possible, how heavily do you design-in mitigation measures for each one?
There gets to be the trouble justifying a hard capital investment increase (with no identifiable increased cash stream) to offset a debatable risk liklihood, magnitude, and timing.
After the fact, you can clearly identify the clean-up and rebuild as the cost of being back in business after a catastrophic failure . . . that is largely covered by insurance. The justification becomes much less nebulous.
I have gotten into some of these Catch-22 type of safety or other catatrophy mitigation investments. It's harder to financially justify than you might think. It helps if the management has a strong safety orientation, but some of these decisions are still tied to the probability of certain bad things happening. Everyone wants to simply say, "then design so that those bad things don't happen and there won't be a need for a loss to be mitigated". Again, easier said than done.
You make good points, David12345. I would suppose this falls into the world of risk management. Without government regulations forcing a company to provide this type of safety apparatus, the risk management folks may calculate that the potential risk doesn't warrant the investment.
Interesting that you mention risk management, Rob. Risk assessment analysis is used by insurance companies to determine exactly those different kinds of risks. So I wonder why such risks--and the needed coverage for same--haven't already been factored in via the plant's insurance policy?
Without the availability of the fire-dampering set-up that is discussed in this blog, it wouldn't be factored in. But if this set-up were available, I would imagine the decision as to whether to deploy it would be assessed based on cost versus the potential exposure due to a fire that can't be put out.
I think those are good points, Rob, about the mechanics involved. But I'm still curious about the insurance aspects. Surely these plants need insurance, and either insurance or government regulations will dictate what disaster mitigation strategies are used, right?
I think you're right, Ann. The insurance companies would probably do a straightforward calculation regarding the cost of an accident with and without the damper, versus the cost of the damper and the likelihood of an accident. I'm not confident the government would do the same analysis if they got involved. The government might come up with overly strict regulations that wouldn't ultimately get enforced.
Rob, perhaps this seems to belabor the obvious, but it's not obvious to me. What regulations would be "overly strict"? With systems this potentially dangerous, I would want regulations that take in more cases and produce fewer errors, and therefore accidents and disasters, not ones that take in fewer cases and produce more problems.
What I was referring to on "overley strict" is the continual complaint from business that government regulations are arbitrary and don't address real needs, real dangers. Then, as with the BP setup prior to the Gulf accident, the regulations were not enforced. So, I was being very general. A good example became visible during the recent discussion of the oil pipeline from Canada. Some years ago, the government had strict regulations regarding 127,000 miles of gas and oil pipelines. While the regulations were strict, the government had one inspector. I'm not sure what the situlation is now.
Disasters such as BP in the Gulf and and the Exxon Valdez in Alaska, and even more so the mess at Fukushima, show up how inadequate our regulations are, as well as, often more so, how inadequate enforcement procedures are. I find it hard to take seriously the complaints of businesses about regulations stifling innovation and all that. Protecting people, animals and "the environment" should be a normal cost of doing business. If it weren't for pioneers like Ralph Nader, we'd still be putting up with Pinto car fires and worse. Instead, we let Chinese citizens put up with Foxconn and with their own government that allows Foxconn, since businesses that offshored US jobs over there were too "stifled" to treat American workers like human beings and follow reasonable procedures for protecting us and our resources.
Well put, Ann. Myself, I lucked out with my famously unsafe cars. My first car was a Corvair --the car Ralph Nader made his reputation on with the book, "Unsafe at Any Speed." Later on I owned a Pinto and I suffered a rear-end collision. No flames, though.
Thanks, Rob. Glad you are still with us and survived your Pinto and your Corvair. Those incidents, among other things, convinced me not to buy American cars, and I don't: I buy Japanese, specifically Nissan.
Yes, I'm lucky. Good for your for choosing safe cars. Could be that U.S. cars are getting close to matching the quality and safety of Japan now.
I grew up in the Detroit area, where every job was tied to the auto industry in one way or another. When I was growing up, there was a stigma about owning a non-U.S. car. The attitude was that "When you buy a foreign car, you take away your neighbor's job."
That ebbed a bit beginning in the mid-1970s when consumers even in Detroit started purchasing cars that made sense -- and were not necessarily Detroit cars.
I was in my twenties when all that was happening and it impressed me deeply. We had originally bought my first car, a '76 Toyota, after the oil crisis because it got better mileage, and even though those early models needed adjustments to suit taller Americans, I was impressed at the easy-to-understand user interface, aka the controls and dashboard. Many older American cars still have esoteric, hard-to find controls for basic and important things like the headlights, which I can't understand. And yes, I got angry looks and hand signals on the freeway in those days for driving a non-US car, even in California.
Wow. I'm surprised that was happening even in California. I agree with the user-friendly interfaces in Japanese cars. I went through a period where I rented cars frequently. When I would step into a U.S. car, it was all bumping elbows and knees, and I'm not tall. And it was always difficult to find the headlights switch and the wipers switch. When I would get into a Japanese car, everything fit and all of the switches were in logical places.
Yes, that harassment went on for several years, into the mid-80s when I was living in LA. Your experience in rental cars sounds just like mine. It was disorienting and, a couple of times, downright dangerous, especially the headlights. I had to drive without them a few times, fortunately at dusk so that limited my mobility severely. Another time I had flown back to the SF Bay Area from LA on a business trip. I had to stop by a friend's house so he could show me where the dang headlight switch was so I could drive at night. It was some knob way under the dashboard down near my feet, invisible while sitting in the driver's seat. I was very glad when American cars began adopting the same user interface conventions.
I know exactly what you mean about the headlight switch. I always felt like I was the stupid one, thinking that everyone else in this country probably knows exactly where the headlight switch is. Another real winner is trying to find the button that releases the gas cap door. Sometimes I've found it under the front seat.
Well, that's funny. I always assumed the stupid ones were those who put it there in the first place--since when are headlights an afterthought in car design?--and neglected to also put a great big red arrow on the dashboard pointing down and big red letters that said "headlight knob here." I got the same argument about "everyone knows this" from that friend whose house I stopped at for a 101 on US cars. I pointed out to him that obviously this was no longer the case, and many people were now used to the Japanese controls clearly marked with easily identifiable symbols and located near eye level so you couldn't miss them. Glad I never had to find the gas cap door switch on those cars. Guess that must not have been an important design element, either, since its location also appears to be an afterthought.
The line-of-sight is important. My 16-year-old daughter is learning to drive. We were out the other day at dusk in my Ford minivan. She asked where the headlight switch was. I told her where it was, but she couldn't see it, The steering wheel blocks the view of the switch. I've had the vehicle for a few years, so it didn't occurred to me that there's no line-of-sight to the switch. If you don't know where it is, you have to feel for it. You also have to duck your head around the wheel to see if you have it on running lights for full headlights.
Wow, that's really bad design, Rob. Does the steering wheel have a tilt adjust? Even if it doesn't, that's ridiculous. My lights are controlled by a level coming out of the steering wheel--impossible to miss. You didn't say what kind of car that is, but mine's a Nissan.
Yes, it is a bad design. The steering wheel does tilt, but that doesn't help the light-of-sight much. It's a Ford Winstar minivan. I like the vehicle is most regards, but that light switch was placed in an odd position.
The oil in these transformers is there as an insulator and coolant. The incidence of these transformers exploding is very small, and I'd guess the possibility of something opening the drain and emptying the oil by mistake is greater than the possibility of an internal short-circuit igniting the oil. As a firefighter, our protocols for high-voltage electrical fires is quite clear; protect your exposures, evacuate as necessary, enjoy the show. As far as aircraft dumping fuel; most aircraft taking-off with a sufficient load of fuel for the trip and reserve are too heavy to land without overstressing landing gear and other parts of the aircraft. When fuel is dumped, the aircraft are typically advised to either move to a loiteriing area and begin dumping, or dump as they travel to the nearest airport. The fuel becomes a mist which is quite diffuse and is considered non-hazardous. As opposed to keeping it in the aircraft and converting the entire load to heat immediately after landing.
I would not be too concerned about the oil being dumped accidently. These monster transformers do or should have their vital signs monitored at all times. We're not talking about a $5,000 pickup truck running low on oil.
I looked at the oil evacuation system in the supplied link. Two problems that I saw were the secondary tank in close proximity to the transformer and the theory of operation requiring the integrity of the transformer case to not be compromised so the transformer can be pressurized. At least someone has given it some thought. Pete O.
Adding to Bob's aircraft comment- Long range aircraft carry about 1/3 of their takeoff weight in fuel (e.g. 300,000 pounds of fuel on a 747 with 900,000 pound max gross takeoff weight). The max landing weight is lower, so fuel is dumped if a problem happens on or after takeoff. If the emergency requires an immediate landing, an overweight landing inspection is performed.
Shorter range aircraft such as 737 and A320 can land with max fuel and don't have a fuel jettison system. If a situation requries minimium fuel it has to be burned off. Usually by circling around for a few hours at low altitude where jets are inefficient.
Interesting about the fuel jettison systems. That would be a bummer if you needed to land right now but also had to burn off a lot of fuel because of a lack of a jettison system. What a nail biter. I wonder if instead of circling they could just go sight seeing. Off to your left is the Grand Canyon. I had a 3/4 ton 4X4 truck that I swore had a fuel jettison system with a mind of it's own. Pete O.
We recently had an oil filled pad mounted transformer 'explode'. At least the earth moved for me in my office, about half a block away. Although the transformer case was severly deformed from the internal pressure, there was neither fire, nor appreciable leakage. These are typically out in the open, no longer contain dangerous pollutants, and fairly rarely ignite. I can imagine that it would not be cost effective to add all these components being discussed, or the utilities would be all over it.
Now if it's and underground transformer, downtown...
For many years the headlight switches in all of my cars were on the dashboard to the left of the steering column. The headlight switch was always the farthest to the left, and it pulled out two clicks for headlights, one for parking lights. Even better, it seemed to be the same in all of the cars. If the switch ever failed the replacement was handy at the local auto parts store, and they were mostly all interchangable, only the knobs were different.
The wiper switch was always easy to find, right above the headlight switch, always. So the two accessories needed to drive the car could always be found, even in the dark.
Then things fell apart: some fool put the headlight switch control on the turn signal switch lever, along with the hi-beam-lo-beam select function, allegedly to make it more convenient. So how often do you turn your headlights on and off? And the wper switch moved all over the car, and onto the door in one Nissan that I once rented. All of the switches for everything were on the door. It was a mid 80's Nissan Pulsar, which may have been a nice car but the controls were certainly wierd.
If the safety people were really concerned about safety they would insist on a more uniform set of control locations, instead of allowing this wild "product differentiation" to continue.
The gas cap lid release that I liked best was one that used the trunk key in a keyhole near the fuel door. It was quite secure and very reliable.
William, that made me laugh. The two levers that come out of the steering wheel shaft on my Nissan Sentra are lights and wipers, and they're always there in the same place, as you said. Of course, my car is a 1996, and I don't know if "some fool" changed that yet. I hope not. There are no controls on the door, perhaps because I don't have electric door locks. I would also prefer a keyed gas cap lid release. I have a lever inside on the floor that releases the small gas cap door, and the small door's latch recently got bent, preventing it from opening. Of course, I discovered this right there at the gas station and had to turn around and drive home so we could fix it.
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