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Tuesday, June 22, 2010

About this Morning...

Unless you are one of a very small group of EPB customers served by our R.R. Donnelley Substation, you got a surprise this morning around 5:30 when your power went off. Even though this happened on what is going to be the hottest day of 2010 (so far), it really had nothing to do with the heat or the capacity of our network. Rather, like most power outages that are not associated with a storm, it happened because of something really small cascading through our network to become something large, all within a time of less than one second.

For those of you interested in the blow-by-blow account of what happened, here goes. First, a number of birds congregated on a pole near the square in Glasgow and caused a short circuit from a 7200 volt circuit to ground. That fault should have been cleared by the nearby Front Street Substation circuit breaker, which would have opened and closed, clearing the bird issue and causing only a momentary blink to the power of about 300 homes and businesses. This morning, that circuit breaker failed to do its job, so its backup protective device took over. That device is something we really don't like, and we are actually preparing to replace, but today, on June 22 2010, it was still in service. This device, a grounding switch, creates another fault on our 69 kV transmission line so that yet another device at our Haywood Substation operates to clear the fault. That circuit breaker at Haywood did interrupt the circuit and the fault, but that operation created a very large outage affecting nearly everyone in Glasgow.

Once the EPB team got some pants on and got rolling, we were able to diagnose the problem pretty quickly and started getting Glasgow's electric power back on. All but that original circuit at Front Street were back in service an hour later. We finally bypassed the circuit breaker that failed to properly clear the fault initially and our folks are still doing triage on it to ascertain why it failed to perform. Hopefully it will be back in service and all of our assets will be available for duty later in the day when the temperature is supposed to be 100 degrees. This is all in a day's work at the EPB.

This whole event just underscores and validates our decision to add a second power delivery point to Glasgow (which is under construction right now). By the end of the year an event like this would affect a much smaller segment of the community since the transmission circuits will be smaller and more redundant. The ground switches and Front Street Substation and Industrial Drive Substations will be removed and replaced with modern protective devices driven by our ubiquitous fiber optic network. Still, even with all of the new technology that is on its way, strange events relating to birds, squirrels, car accidents, and other odd circumstances will happen. When they do, you can count on the EPB team to jump up and take action. That is what we do!


NativeSonKY said...

I've lived in a lot of places around the U.S., and the EPB is by far the most responsive electrical service I have ever witnessed. When the power goes out, I know it will be back on soon and this is a rarity in the public service sector - good work guys & gals!

John in Glasgow