This Tabblo started out on a completely different subject. Woody posted his powerline Tabblo and I mentioned the unique ones I had seen in New Mexico. I promised him I would do a Tabblo on them. And I still will! I ran out of memory during this trip so didn't get all the pictures of the towers I needed.

But, while researching this huge power distribution line, I found something even more interesting (to me): a DC interconnction between the Texas power grid and the Southwest US power grid.

(Warning: Boring technical stuff follows.)

Most people don't know (or really care) but the power grid in the US is not directly connected across the nation. There are really three grids, all running independently: the Eastern Interconnection (which includes the midwest), the Western Interconnection, and Texas.

While they are all running at 60.00 cps, they are all out of phase with each other. (This is called "out of sync" in the industry.) So the three systems cannot just be "plugged into" each other. That would cause widespread damage as the two systems tried to compete for speed control. And probably melt or vaporize the lines connecting them!

Anyway, I was curious where the two ends of this powerline went. From the location and direction of the line of poles from where it crosses US84 south of Las Vegas, NM, it probably went to Albuquerque at the western end.

So I began to follow it "eastward". Only it wandered around like a drunk contractor put them up! It went east over a ridge from the above location. Then appeared just to the east of Santa Rosa so it had to have gone south somewhere in there! But it went over a hill and out of sight again. I knew it passed near Melrose, south of Tucumcari and not far from Clovis.

As I went south from Melrose, with no frames left in my camera, I "found" the powerline running along the highway but not as far as I recalled. It turned in the middle of nowhere and went east. I had to continue south and couldn't continue "pursuit" from this direction. So I didn't get any close pictures of the towers. This trip.

On my way back through the area, I came from the other side, through Muleshoe, Texas. I started watching for these distinctive towers on the horizon as I approached Muleshoe and noticed a dramatic increase in the number of powerlines in the area. That meant some kind of major electrical nexus, probably a big powerplant. I found it NE of Muleshoe. It was two huge units; I guessed they were combined cycle units from their size. These are gas turbine generators with steam boilers run from the hot gases of the turbines; this arrangement is both the most efficient power production system and make oversized powerplants.

The pictures above are that powerplant. This is a coal fired plant, not a combined cycle, using Powder River coal from Wyoming. They had to have been oversized due to the high ash content of the coal not to mention each unit was 500 MW capacity! Those powerlines are exporting a gigawatt of electricity at full load!

Now I had some powerlines to follow; these had to tie into the ones I was looking for. As I followed them westward, I ended up going the same way I had planned to anyway on into New Mexico. I finally found where that line plus a bunch more ended up.

Outside of Clovis, NM is a huge switchyard. There are six powerlines coming into this switchyard from the east. Power likely flows both ways through many of them as demand dictates. But only three headed west (next tier below). The big ones are the east end of the powerline I was looking for!

The two smaller ones go to Clovis from the switchyard but the big ones are special.

Tracing those big towers back from the west (the pictures above), they end up in this building. And another set of powerlines come from the switchyard to it (lower right picture of the switchyard set). It took some research to identity this facility.

There are only a few like it in the US. It is an AC to DC to AC intertie converter to connect the Texas and Southwest out-of-phase regions of the US. Clovis is the last of the Texas area power region at this point. The big line goes west to tie in at Albuquerque, some 250 miles away, with the SW US region.

The size of the towers and the dual cables configuration implies to me that these are probably 230,000 volt (230 KV), high capacity lines. What impresses me is the technology which must be required to make this conversion. I have been unable to find the details of how this is done . Maybe I can beg someone to allow me inside for more pictures!

Electrical power in the US has three "phases", all 120° out of phase with each other (One electrical cycle of the 60 cps is 360°). Generally 480 and higher voltages are three phase because this gives motors much more torque. The triangular or "delta" layout of the cables on the towers reduces the interphase transmission losses due to the current flowing through each wire cancelling some of the current in the others (induced current). The generators see this as a load and have to make more electricity to compensate.

And by hanging the top cable inside the loop, lightning is much less likely to hit the powerlines. They don't show well since they are much smaller wires but the smaller wooden towers have "lightning protection" wires above the powerlines; the big ones do not.