At least power-wise, that is. Gas pipelines are odd things. Every fifty or sixty miles up a pipe two or three feet in diameter, there’s a compressor station. It sucks the gas out of one pipe and pushes into another. This requires horsepower. some of our stations have twenty thousand horsepower to push gas.
In the beginning and still in service were big piston engines. they operate on principles similar to the one under the hood of your car, except the things are HUGE, four or five thousand horsepower, slow, your car runs several thousand revolutions per minute, ours run at a couple or three hundred, and we burn natural gas.
Why natural gas? ‘Cuz that’s right there. We have a pipeline full of the stuff. Indeed, these stations in many cases were originally totally free of the local electric utility because they’re quite often in remote areas. What electeic power that was needed, for the lights at the office and such, that was taken care of by yet another natural gas engine powering a generator.
As stations upgraded and utility company electricity became available, stations added electrical loads for things and the old generator was relegated to stand-by service, set up to come on automatically when the utility company’s power failed.
That was us at the station I’ve been working at the last couple of weeks. Our old utility company power system was on the same 13,200 volt line as the gas station/grocery store up the road, along with the farm on the other side…Â We had three pole-mounted transformers the same size as the ones you’ll see in many residential neighborhoods, except ours took that 13,200 volts down to 480 instead of the 240/120 volts your house uses.
Power failures during stormy weather was a fact of life, and our stand-by generator got a frequent workout. We had an automatic transfer switch. When the utility company gave up, the transfer switch would start the generator, then, when the generator was pumping out 480 volts, the switch would transfer to plant’s load to it. When the utility company got its stuff together and the power came back on, the switch would transfer us back to the utility source and let the generator run for five minutes at idle to cool down nice and easy, then shut it down automatically. It did this without any human interaction at all. Neat.
Today’s festivities changed our status significantly. Since our NEW 9000 horsepower motor would not run on the old power system, a large chunk of the project, MY chunk, has been to bring in a new utility feed at 69,000 volts. We transform that down to 13,200 volts to feed that big new motor’s drive system, and we also transform it down to 480 volts for the rest of the plant.
When I got to the station this morning,w e had both systems hot, but the new transformer wasn’t feeding anything. During the day, we shut down all the electric power (480 volt, anyway. We have some control stuff…) and cut the old system loose and tied in the new system, and we moved the generator’s output cables to a new transfer switch. That was a seven-hour task. When I left, the place was running normally, but we’re now on a 69,000 volt transmission line feed. 69,000 volts is the lower end of the electrical Big Leagues: Transmission!
What’s the difference? Distribution feeds residences and small businesses. If a residential distribution line goes down,well, some of you folks can relate stories about getting power back on after a thunderstorm. I can tell you how long it took to get those circuits on after a hurricane: 2-3 weeks. Transmission lines come up first. They have to, because the transmission lines bring power into the distribution substations.
Our new feed also feeds the major city in the area, so it’s unlikely that said line would go out without the utility company mobilizing every possible resource to return it to service. We have some other advantages built into the system, too, and I’m sitting here thinking that the poor ol’ generator will get mighty lonesome except for the regularly mandated test runs.
Now all I have to do is get that 9000 horsepower motor to run. I’m confidant of that event happening in the coming week. And then my life will have lost some major stresses.