Electric Power Research Institute

It’s not Guinness Book of World Records material, but electric company technicians and researchers may have set a speed record in replacing a transformer as part of a drill to determine how the power grid could recover from an attack or a natural disaster.

As I wrote last week, the Electric Power Research Institute, a nonprofit utility consortium, joined with the Department of Homeland Security and CenterPoint, a utility in Texas, to ship transformers on an expedited basis from a factory in St. Louis to a switchyard, or substation, near Houston and then work as quickly as possible to set them up.

The trucks left the ABB factory last Monday and reached Houston on Tuesday. The replacement transformers started running late Saturday. Initially, the organizers of the drill had thought it might take until sometime this week to get them going.

A crucial part of the exercise was rethinking the transformers. Normally, transformers of this type are single units. But the odd nature of electricity on the high-voltage grid prompted workers to break the voltage into three parts, which also ensured that the replacements would be small enough to transport on roads.



On the high-voltage grid, electricity is moved as alternating current, meaning that the electrons shuffle one way and then the other 60 times a second.Their jump back and forth, like a line of dancers kicking in unison, is how the energy is delivered. This is called single phase current, which is what household equipment uses.

But at a power plant, electricity is not generated that way. It is generated in three phases, like three lines of dancers out of phase with each other, in syncopation. (Electrical engineering is closely related to witchcraft, but a textbook explanation is available here.)

The power on the grid is high-voltage to limit transmission losses, and it must be reduced to a lower voltage for local transmission and distribution. Usually a single transformer does the job. But the research institute designed a quick replacement system using three individual transformers, one for each phase. It is somewhat analogous to the the slim, doughnut spare tire in a car, although these transformers would be permanent.

If the experiments proceed, the next step is a transformer that can be quickly configured to take in power at a high voltage and give it back at a choice of different lower voltages, making them slightly more interchangeable, and then developing a strategic stockpile.