How to Kill a Transformer


Transformers are the most vulnerable components in the power grid and they are under attack.

The main components in our power grid distribution system are transformers.  They step up the generated voltage to a higher level for more efficient transport over very long lines.  Then they step the voltage back down in several stages for final consumption.  These transformers are located at the power plants and thousands of substations.  They are big and right out in the open.  Weather does not bother them, but bullets do.  They are the weak links in our power grid.

Last year someone decided to shoot out the transformers at PG&E’s Metcalf substation in Silicon Valley taking the substation out of service.  Luckily, PG&E was able to reroute the power to prevent a total blackout.  But it took months to get replacement transformers and restore service.

This is a major wake up call to the utilities.   Terrorists, or disgruntled customers, can easily take down a substation with a rifle at long range and get away with it.  The transformers are defenseless as they are not covered or protected in any way.  Furthermore, replacement transformers are hard to come by.

Power transformers are not an off-the-shelf item.  Most are custom made to match the utility’s system.  Each transformer is unique so requires special manufacturing efforts.  It takes months to make small transformers and as many as two years for the big transformers.  And they cost a fortune with small ones going for up to $1 million and as much as $10 million for the big ones.  In addition, transportation is an issue.  How do you ship a monster transformer weighing a couple hundred thousand pounds?  So while replacements are possible, it takes a significant amount of time.  This could cause a black out for months or longer.

On top of all that, there are only about seven transformer manufacturers in the U.S.  And most of these are not typically that busy.  Even so it would be a major problem to get fast service from a U.S. company for custom products.  Not that many of them make the really big high voltage transformers.  However, there are other transformer companies worldwide but service would no doubt be slow, and let’s not mention shipping costs.

Something needs to be done about this, fast.  You know how you feel during even a short few hour blackout.  It is miserable.  Think of all the businesses, hospitals, and government services that depend upon power.  It is a scary thought to think we could go without power for months.  No doubt the utilities are already taking that California event as a wakeup call.  I have not heard what they are doing about it.  And just what can be done anyway?  Special housings?  Bullet proof shielding?  Kevlar vests?  Utilities could keep a spare or two of the smaller cheaper transformers, but it would be too costly to stock a spare of the larger ones.

Most substations are not that secure.  They usually have a chain link fence and maybe even video surveillance but neither of these help when your enemy is a sniper a hundred yards away.  Even armed guards are no help.  It would not take much of a complex or expensive effort to really disrupt electrical service nationwide.  Just ask hurricane and icy winter survivors how bad it is without power for a long time.  So what is the solution?

Since the terrorists now know of this cheap and easy way to hurt us, we had better develop some protection.  In the meantime, it wouldn’t hurt to get yourself a good generator for back up.

Discuss this Blog Entry 26

on Mar 5, 2014

I'm so tired of the plethora of bogus paranoia that passes as technology insight around here. The solution is perfectly obvious and hardly needs be mentioned. Only those that don't understand the problem and/or are looking to take money via the ignorance of others continue to bang the drum of nationalistic fear and dread. You wanna help? Then build a better transformer that the electric utilities must afford despite paying their "non-profit" CEO's millions of dollars in a system allowed to break continually so they can maintain artificially large budgets despite tax-payers being broke.

on Mar 10, 2014

Bogus? This ACTUAL attack occurred on April 16th of last year. What, praytell, is your perfectly obvious solution?

Mine is to plant trees around the substation to eliminate the clear lines of sight and unobstructed bullet paths. It won't stop all potential attacks, but it will eliminate the certainty of success.

on Mar 11, 2014

I don't think you fully red his comment. He's not denying this happened; he is saying that it can be easily resolved and that the cost to resolve it is not that high considering how much these utilities CEOs are raking in, with some low-cost common sense solutions.
You suggested trees. A cheap concrete brick wall around the substations would do wonders to solve this problem, among many other cheap solutions.

on Mar 12, 2014

By my 10/20 vision, this is not a technical problem for engineers. It is problem of the society.
Is there something new about the transformer? We talked about the same transformer issue more than 10 years ago during the last peak of Solar activity. There was no response.

on Mar 10, 2014

This is the second article I’ve seen mention that substation transformers are custom made. I can’t see why. It would seem completely obvious that standardizing on a small number of voltages and power ratings would be a winning approach in many ways — less expensive devices, shorter lead times, much lower system design costs, and so on. “Pole pigs” are certainly standardized; why would substation transformers not be?

on Mar 10, 2014

The reason why transformers are big is because more than a hundred years ago, when George Ferraris (or Nikola Tesla) invented the 3 phase AC distribution model, transformers had to be big. But, Edison's alternative, DC distribution gave no hope for long-distance distribution let alone a national grid at low cost, because you could not step up DC voltage.

Since then, despite that 3 phase AC worked all over the world, it has been agreed that even with low frequencies, the skin effect over long distances really made even fat power lines behave like puny wires, besides which their resistive losses, no matter how low, are not at all negligible. For this reason large transformers must be oil-cooled. And, as Lou says, substations are sitting ducks. But not common targets. Eg the macho way to take them out was not to shoot the substations but to spew carbon dust as UN forces did in Bosnia. Ask UN why.

Gradually however, power generation would go DC but too late for Edison. Distribution will go DC, with DC-DC conversion along the way. Industrial plants will use DC. And only household end-users will use AC, and then again, only for induction motors. Substations will become much smaller and transformers much lighter, and yes, it does not cost to much then to bullet-proof them.

on Mar 10, 2014

What is the purpose of this article? To spread panic err at least paranoia? Let's point out that even though a substation had all of its transformers shot out the lights for the most part stayed on. Why? because power was routed around the station. The installed system architecture included a backup or spare system installed. Most, not all systems are so designed. System designers are concerned with various opens, shorts and groundings, not unlike those caused by a rifle, and already have contingencies in place. A coordinated attack on multiple substations is likely required to sever both normal and alternate sources to an area causing lights out for months. Please don't write article to simply perpetuate the paranoia around us.

on Mar 10, 2014

The scare-mongering is a bit much in this article. Yes, the power grid is vulnerable to all sorts of attacks. This writer focused on transformers, but plenty of other points are equally vulnerable. Looking around the world, functional power grids are a sign of peace. In war zones, people run on small generators, ad-hoc local "grids", and do without. Even in this country, critical users like hospitals, and an increasing number of private homes and businesses have backup generators. (Gas stations are inexplicably banned by law from operating on backup power, but that's a separate problem)

But to address the transformer issue only, the one practical solution I can see is greater standardization. Do we really need such a wide variety of voltage and KVA ratings that every high-power transformer has to be custom built? Could we not standardize on a few KVA ratings with plenty of taps, such that manufacturers could keep a few of each size in stock for quick delivery? It's not like they're going to go bad sitting in a yard for years.

Beyond that, yes, if we have a civil war, we won't have much electricity. But the solution to that is to avoid having a civil war.

If the issue is grid reliability, transformers are only a tiny part of the concern.

on Mar 10, 2014

The scariest part of the story isn't mentioned in this article. Various government agencies successfully buried this incident for several months before it was leaked to the public. Apparently, we can not be trusted with this information since we could only contribute to the problem and are not smart enough to offer solutions.

on Mar 10, 2014

Spare transformers are also needed in case there is a significant geomagnetic storm with damaging geomagnetically induced currents (gic).

Why are so many of these transformers "custom" orders? Is it the specific electrical ratings, coil configurations? Or, is it the mechanical mounting footprint and location of the terminals (to match existing wires / buss connections)?

There are the obvious questions of risk / benefit, a standard engineering question (Or, paranoia / practical as it has been alternatively phrased). Also, cost - benefit. How should we spend our limited resources for risk management, to prepare for the big geomagnetic storm, a hurricane, earthquake, tsunami, the super volcano, War?

Otherwise, this would seem to be a great topic for a magazine article. Why not have a power industry transformer expert write an overview on power transformers and why they seem to be unique in many installations. Also, why are there not more modular approaches with standard electrical and mechanical configurations?

on Mar 10, 2014

Those who consider this article scare-mongering are simply not aware of the extent of the vulnerability of life in the developed world. It is not only the lone "terrorist" who is a threat to the electric power grid. One EMP bomb exploded over the center of the continental USA would also take out the power grid along with most things electronic, leaving the US in the 1800s. Those who study such scenarios predict that if this were to happen, 90 % of the US population would not survive it. The large transformers are made in China and the likely source of an EMP attack would be N. Korea or China.

It is high time that Americans wake up to the reality of their actual situation. Some of us have and no longer live in N. America.

on Mar 11, 2014

Even the smaller transformers mounted on utility poles can fail catastrophically, as happened in my neighborhood when an unfortunate squirrel shorted the transformer. It took more than 24hrs to replace it. Would the power utility really suffer a financial hardship if the local distribution transformers should be stored within a few hours' drive from the affected communities?

on Mar 11, 2014

Just like 9/11, 7/7, or the Boston bombings were inside jobs, so could this be. I tend to believe we'd better switch to our own trusty little back up power supplies; be it wind, solar, water, piezzo that can use acustic and mechanical vibrations. Currently, we are at the mercy of both mother nature and big-bro, at any given time, the latter's worse though. Our own power supplies should soon go low voltage anyway, maybe DC, as many things can be operated on it and have a spare dc-ac converter at hand if needed. Then; bugger all the politicians and CEOs as they go hand in hand to screw us all anyway they can.

on Mar 11, 2014

Why there aren't N+1 backup and spares? Not only is the initial outlay unpleasant to stockholders (greed), these expensive transformers are taxed as inventory in most states. That's why spares have been pared-down in most commercial environments. At best, equipment is warehoused in states with no inventory tax. At worst, it doesn't get ordered until something fails.

on Mar 11, 2014

Simply make a concrete transformer vault

on Mar 12, 2014

My father worked for the local power company and about 50 years ago, he related a conversation with an officer in the US Army reserve. How to take out the power system: Just what the terrorist did in California. Take out the big ones. You just do not buy them at the corner hardware store. With the religious and political crazies running around it was just a matter of time.

on Mar 12, 2014

People, the solution is very simple; put the transformers in a cinderblock building with a garage door for access and replacement. It provide protection and destroys line of sight for targeting.
If you want a better cooling, then bury the transformer in a concrete vault with steel doors for access and replacement. Neither solution is difficult or particularly expensive.

on Mar 13, 2014

I've worked in a few small substations. If you're not wearing a cap, your hair stands up due to the electricity in the air. There is Ozone in the air because even at the low 30,000 volts the Air is somewhat conducting. Even "non-conducting" concrete is kept away from the power equipment. Seattle has several residential powerstations enclosed in a grounded metal grid, the eclosure is several several times the size of the original powerstation equipment base.

on Mar 12, 2014

Actually, this threat has been recognized for quite some time, by both the gov't and public alike. The government has had a program called the "Recovery Transformer (RecX)" underway for a while now, and I actually remember reading an article in Omni (!) magazine back in the 80's about ways to knock out US infrastructure, and this was one such method mentioned.

on Mar 12, 2014

Just found the Omni article - Jan 1989...By G. Gordon Liddy!

on Mar 12, 2014

I would suggest "solar cell arrays". Decentralize the power grid system. Shoot my solar array and you may knock out my power but you wouldn't have the whole block or sections of town/city without power. I know that the electric generation companies will have problems with this as it costs them money.

on Mar 13, 2014

As I remember the Metcalf attack was called a "trial run for a terrorist group" by Homeland Security. Near a dense suburban neighborhood, it took 30 minutes to shoot out 18 transformers and apparently some underground cables were severed. Police responded like an hour later, well after the perps left the scene. Not very competent of terrorists or law enforcement. Of course "real terrorists" would use C4. When I lived in the Mojave Desert gun nuts would try to shoot the insulators on the 500KV DC line towers. Luckily most gun nuts are drunks.

on Mar 13, 2014

Reference 40% of US generated electricity is squandered in system losses, mostly in deteriorating East Coast infrastructure. (Congress won't pay to fix; even Interstate bridges falling down.) Sort of takes away the environmental advantages of electric cars (that and the 20% efficiency of Coal burning plants, like "Four Corners" for LA (Emits 1000 times the radioactivity of a nuclear plant.) (Eastern plants only 100x nuke plant.)

on Mar 13, 2014

So the figure was 25% power loss to resistance for the 1000 mile Bonneville to Sylmar DC line. And isn't a quarter wave antenna for 60 Hz only 750 miles? We had 330KV AC lines behind our school; lines emitted enough power to make a dead flourescent tube light up. Oh. yeah: transformers are fairly efficient at 95% or so. But 330KV doesn't get reduced to 110V residential in one step-down. One client running a small hydro plant (profitable; subsidized by the public) had quite a few mangetics before his power merged with the grid. Of course the Metcalf attack could have been to test the Power Company's Software with an eye to shutting down the whole State.

on Mar 16, 2014

Aside from the comments being 5 times longer than the blog post, I've actually learned a lot from them. (Felt sorry for the squirrel though) There are more subtle ways of causing a blackout aside from killing a transformer. Anyway, shooting a transformer doesn't immediately effectuate a blackout (unless you aimed for the wires). The oil insulation will leak first. Without the insulation, the transformer will burn itself and then cause a power outage to whatever load it is carrying. A shorted transformer is different, as with the squirrel case, as it would only trip the fuse or circuit breaker of that branch.

on Mar 31, 2014

It is called infrastructure people and concentrating on the components is not the answer and every one of you already know that a systematic, coordinated approach must be followed for every link in the critical infrastructure. Cement walls will address projectile weapon damage, but so does a thicker outer jacket design for all future transformers to be built. Placing the infrastructure underground does more than just protect it from terrorist attack, it frees up valuable surface area that can be repurposed for housing, mass transportation and waste disposal - an integrated system that increases efficiency.

I could go on and on, but my final thought is that if everyone keeps being distracted by the micro issues and allowing money to equal election victory, we are certainly doomed to keep failing miserably as a going concern. Our future plans and budgets need to make sense for the long run and making legislators accountable to perform for the people rather than money and power is the first step towards regaining our country and assure a viable future for the coming generations.

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Blogs on topics such as wired and wireless networking.


Lou Frenzel

Lou Frenzel writes articles and blogs on the wireless, communications and networking sectors for Electronic Design. Formerly, Lou was professor and department head at Austin Community College...
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