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.
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.
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.
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...
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