The mill originally ran power to two cabins. The owner, a successful business man and entrepreneur, was well known and respected and often hosted hunting / fishing excursions that included local politicians up to the office of Governor. It's fun to listen to the stories of how all the cabin furniture was pushed to the walls to make a dance floor. You can still see the old wires and sockets that ran from Hemlock to Hemlock and lit up the whole outside including the creek and waterfall. The cabin is still nearly as it was in the 40's. Over the last few years my friend and I have been repairing the powerhouse containing the generator. Last year a large tree fell across the roof taking almost half of it down. We were able to carefully dismantle it and put each piece back the way it was. The view from the swing is over the wheel and out to the lake where boat after boat of tourists come to photograph the water fall. Each year when we are there some tourists get the added attraction of seeing the wheel spinning. This year we reinforced the walls inside as rain and water flowing over the falls and into the side of the building rotted the wood to a point where it was standing by two corners. We used lumber cut rough sawn like the original pine and the added framing all looks original. Here's a shot of the label on the generator. It says, "Western Electric", a popular brand back in those days. Probably built by GE as Flux said and sold under the Western Electric brand name. I see I was wrong on the volts, it says 115. Sorry the pic is so blurry, I tried many shots and this was the best. I believe that it would still work. Nothing has been disturbed and the brushes still move smoothly against the springs holding them to the armature. Still, I think it is best left undisturbed and I don't want to mess with 14 KW of direct current. There is one chain in the drive that has been removed and hangs in another shed so that when the wheel turns now it is free wheeling, only needing a fraction of the water to spin it.Andy
Just treat it with the respect you'd give any 120V circuit: Don't grab it or fall into it while it's live. (As DC it has a somewhat higher tendency to lock up your muscles if you get connected to it, and won't "buzz" if you accidentally drag your hand across something that's a "little bit live". But it's not going to jump out at you.)
Work out the wiring first and figure out how the regulation and excitation works and how to cut it off. With the excitation shut down it will only generate by residual magnetism, producing a a very low voltage (if any). And you'll want to check the wiring for insulation deterioration before spinning it up with excitation enabled, to avoid a fire hazard.
I'd be more concerned with getting my hand or clothes caught in the moving parts than with electrocution.[ Parent ]
What you wrote,
(As DC it has a somewhat higher tendency to lock up your muscles if you get connected to it
is what always scares me about high voltage DC. I remember learning in electronics class way back when that anything over 70.7 volts was getting dangerous and I'm not the most careful person about things. You gave me a good idea though, next time I'm up there I will draw out the whole wiring diagram and ask for an explanation of it on here. Self excitation is way over my head as I didn't even know what it was till a few months back when I read about it on here. Inside the generator are 4 big coils at 90, 180, 270 and 360 degrees. Halfway between 360 and 90 degrees is a fifth smaller coil. I suppose thats the one that gets the rest of the guts all excited. Maybe if I study hard and pay close attention to what you guys teach here, I may be able to make that old genny spin once again.
Gotta go, just looked out the back door and it looks like there's a hurricane coming. Gotta secure the turbine and check on the Tequila...Andy[ Parent ]
The reason voltages over 77 or so are considered "getting dangerous" (and the rules change at 50 volts) is that skin resistance is usually so high (even when sweating heavily) that such low voltages won't normally push enough current to stimulate muscles and nerves even if you grab a hot wire, while voltages in the 75+ level usually will push at least enough to make your muscles twitch, and potentially could do that to your heart if you grab on hard with your left hand.
But you have the same problem with AC and both electricians and do-it-yourself handymen work with it all the time.
The rules are virtually identical for AC and DC at house-wiring voltages:
- Only handle unpowered wires. - (Be VERY careful and keep your left hand in your pocket if you MUST work in a box where anything is still hot.) - Don't grab hard onto anything that MIGHT be hot. (Even if it's supposed to be dead touch it before grabbing it. That way the "twitch" won't make you grab on harder if it turned out to be live.) - Don't get into a narrow space with exposed hot wiring. (Risk is being thrown into continued contact by uncontrolled muscle action if you bump something hot.)
Given the pix it looks to me like you should have no more risk of electrocution working with this thing than with working with an AC system of the same vintage. Main risk looks like the exposed knife switch and the narrow space behind the panel with the hot stuff back there. So don't go behind the panel while the genny is spinning and keep the area in front of the panel clear of tripping hazards until you can get a guard over the knife switch.
= = = = =
I'd proceed by: - Tracing the wiring (and examining it for anything that looks like bad insulation) - Getting the genny to turn freely. - Maybe "stoning" the commutator. - Fixing up any wiring that looks like it needs replacement. (Note about old wiring: Flexing it may make the insulation flake off, so don't disturb it unless you're replacing it, then replace everything you have to bend (except the enameled wire in the motor/generator terminal box). That means pulling new stuff through conduits if necessary. - Spinning the genny with a motor while getting the genny/control panel working under no load. - Going up to full operating voltage and lighting a small load (like a nightlight bulb.) - Hooking up the chain. (Don't want to put multiple horsepower into it until you're sure it's not shorted.) - Loading up the system inside the shack (with new, temporary, loads, like a few incandescent lights). - Inspecting and fixing up the wiring to/in the cabins before powering THAT up.
Of course there are lots of points in there where you can determine if there's a problem that means you should stop now. (For instance: No point in working on the cabin wiring if the genny isn't going to work. No point in hooking up the genny to the wheel if the genny is shorted.)
And of course you'll want to keep extinguishers handy and anything flammable away from the genny and panel in the shack until you've got it checked out and running solidly, just in case.[ Parent ]
That all sounds like sound thinking. You've made me consider re-energizing that old mill, but only after a lot of homework. I think probably all wires and components except the generator would need to be updated. We could leave the old panel for show and build a modern and compact one. Also the wheel itself would need alot of work to be able to stand the amount of water it would need to turn those gears. Right now the buckets are a little leaky, OK for show but we only use a trickle to make it turn.
Thanks again for that detailed and well thought out post.Andy[ Parent ]
Of course you'll need to fix it up to pull kilowatts off the genny. But the genny's resistance to turning is just mechanical friction plus the power delivered or lost in internal losses (including powering its own field coils). So if there's no electrical load there's nearly no mechanical load.[ Parent ]
