When your dam is empy on the inside its a ...

Hollow Dam.

Hollow is our latest project. It's another old Algonquin site out near Gouverneur, NY. A group of us took a nice drive out there this week to look at what it would take to give the site a control upgrade much like we did at Burt Dam. The weather held out pretty good for us and we got a lot done.

You can see the "open" turbine at the left. 

The site has some very unique turbines. They are vertical cylinders that contain the turbine and the generator and act as a gate. The entire cylinder raises up by about three feet which opens the "gate" allowing water to flow into the cylinder and through the turbine. The turbines themselves have variable pitch blades allowing the operator to regulate the water flow and power generation to some degree. Unlike most of our plants, there's no real powerhouse around the turbines, which makes winter repairs rather annoying. Beyond this, though, they seem pretty reliable and produce about 1 MW/h (1000 KW/h) at peak. The two machines are identical and are rated at 530 KW/h each but tend to max out around 500 which is still good.

This is the rig around the two turbines to allow for maintenance.

Because of how the turbines are configured, the control room is an entirely separate building down below the dam. It's a bit cramped but nice and quiet, unlike most of our plants where the controls are in the same building as the turbine. The control panel appears to be similar to a lot of the plants I've seen recently. It was upgraded in the 80's and from there the bare minimum was done to keep it running.

The PLC is an old Toshiba model (same as Burt) but is not functional at all. Instead of spending the money to get it working it was bypassed as much as possible and is now run only on manual control. For Hollow this is okay (not great) because the operator lives on the premises. The previous owners wouldn't have gotten away with that any other way.

Kinda cramped, but quiet and warm. 

Richard and I went through the panels and started looking at the electrical drawings. The panels are pretty cramped too, having been pretty efficiently designed to be as compact as possible. You can see the two control panels and their cooresponding breaker cabinets in the picture. Out of frame is another control panel primarily containing protective relays along with a few non-functioning switches and the PLC cabinet which is near the floor.

Unfortunately there isn't any good space on the panel for one of our touch screens. At this point I'm thinking that we'll probably build a mount for the screen and put it on the desk which is at the left of the picture. I really like the Beijer panel we used at Burt and the operator likes it too. The operator at Hollow is less technical then the one at Burt and I don't think putting a full PC there makes sense. We'll probably use a wifi android tablet or iPad for him to keep an eye on things from his house. That will also give him access to the reporting tools we're setting up.

Overall it looks like a good little project. I'm not exactly looking forward to two weeks in Gouverneur (or maybe Watertown), but otherwise it looks like fun.

... so why is it called "Hollow Dam"? Well... we found/saw the remnants of the original dam...

Kinda looks like it was empty on the inside...