petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
The answer then is to pass a law banning such storms.
Overhead Power Lines Dangerous To Life and Property
- Thread starter mbrooke
- Start date
- Status
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Even if there was such a law, just how would one go about burying this kind of line. You can pass a law mandating just about anything but being able to carry it out is something else.
It would be just another boondoggle like the high speed rail in CA that goes from nowhere to nowhere.
maybe a better solution is having power generation closer to where it is used so transmission lines are less necessary.
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
To be honest any transmission line over 150 miles is better being left overhead, but those around trees could be technically feasible and economical in a relative sense.
Co-gen is certainly viable in theory and should be researched further.
Don't know about your supermarkets, but most of the big ones around here have some type of back-up generator. Those that have full backup and the generator runs behind the store in a sound enclosure or in a dedicated room, you don't hear it running, the inside of the store functions like normal. In theory you could do the same with a gas turbine, and, use the exhaust heat to drive absorption cooling, domestic hot water and heat in the winter. Nothing is wasted, gas mains come buried.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Cogen failed pretty miserably once the subsidies ran out.
Just about every place around here that has food freezers has some kind of NG powered backup generator. The sewer pumping stations are handled that way too.
gas turbines are pretty efficient when run full bore. but the reality is that they would probably not be running at full capacity most of the time.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Here in the south, very few supermarkets have generators, and the ones that do, it usually is just lighting and registers. Most can go a couple of hours if they cover the open coolers, and dry ice. Many have Kirk key set ups for portable connection to large generators in areas that have frequent power outages due to weather. Many recoup heat from the refrigeration system for hot water needs in the
store. We do have a customer that is planning on permanent generators for their supermarkets in the next couple of years. Probably in Cali, since they can’t seem to keep their power one.
kwired
Electron manager
- Location
- NE Nebraska
Around here transmission voltages typically are not threatened by trees. Most the medium voltage local distribution isn't under too much threat, it is the low voltage secondary that is usually subject to damage by trees.
People that don't know much about it don't understand how impractical or expensive it is to put ALL power lines underground. Most the transmission level voltages are still best to be overhead cost wise.
kwired
Electron manager
- Location
- NE Nebraska
But then everyone cries about coal trains, natural gas pipelines, etc. needed to fuel the generation station.
We have a wind farm near me that was finished around a year ago. Still not running though. Why? Transmission line that they were depending on to export power on is held up in legal processes, people whose land it will be crossing don't want it and were fighting it even before they started building the wind farm.
drcampbell
Senior Member
- Location
- The Motor City, Michigan USA
- Occupation
- Registered Professional Engineer
Or an excise tax on fossil fuels.
Climate Expert James Hansen: “We've Got An Emergency” - DCMediaGroup
Climate scientist Dr. James Hansen warns that feedback loops may be accelerating the impacts of climate change faster than societies can adjust to them.
www.dcmediagroup.us
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
I was in Minnesota a couple of years ago, they had quite a few windmills, but only one out of five on average was working. (At least turning, don’t know if they were actually putting out). Where I live is a tourist destination, so they won’t let the power company clear a very wide right of way. They claim because of that, if a tree falls on the line, the property owner can be charged the cost of the repair. Never heard of anyone getting charged though.
kwired
Electron manager
- Location
- NE Nebraska
Many times just a branch (sometimes a large one) falls but never hits the line unless it was hanging over or pretty near to being over the line.
Otherwise you often need weak base (old rotted core) and/or pretty severe winds that uproot the entire tree for it to be able to fall on lines.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
All of our outages are trees falling on lines, usually tall pines. Usually snaps the line, but not the poles. Wind plus saturated ground, or ice.
kwired
Electron manager
- Location
- NE Nebraska
Tall pines not very common here. I can see those being the entire tree going down more often than that happens here with most trees - other than ones with old rotten core near the base. Big cottonwoods and maples are common and usually getting a branch that breaks off and not the whole tree coming down, especially in thunderstorms or ice storms. Both those species of tree grows fast but is somewhat weak for withstanding winds compared to many other species. People plant them to get shade trees in faster time, then when they are an excellent shade tree along comes some storm that takes a lot of it out and they end up cutting the entire tree down.
We had a storm a few years ago that had several inches of rain over a couple of days followed by 70+ MPH winds. Huge oak trees that would not have been damaged were uprooted due to the saturated ground. A few thousand without power for up to seven days.
It was a very rare event here.
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
We've had quite a few icing events that took down lines even with no trees in vicinity. I remember a big one that took power out for over a week throughout upstate even into Canada. Don't know if or what effect the storm had on all these 750kv transmission lines running thru here though. Have a lot of these 500 and 750kv lines that run thru to get power down to the city from the big power dam in Messena.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
It would probably be more cost-effective overall for people to just buy a whole house generator rather than paying to berry power lines.
Yes and no. Loops are simple and reliable and you can use cheap sectionalizers on them for instance. But it only helps where loops make sense…on everything that isn’t radial or can be.
And that’s the problem. 90% of a system is customer radials. Not surprisingly 90% of the failures if not more are those same radials. In a loop system typically you have 3 fused or no fused switches. Two to isolate lines on the “loop” and a third connecting a load or feed. In a radial system you have just one. So going looped triples the cost and maintenance on switchgear to make outage recovery very rapid if one of those 10% events happen.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
The closer the failure is to the customer the fewer people are affected. A failure of a big line might cut off tens of thousands of people while the lines running along my back yard only affect a handful of houses. If reliability is a problem, it would be best to start with the things that give you the most bang for your buck like getting tree trimming done in a timely manner. Burying transmission lines is way down the list, especially in rural areas.
Ok so the utility for my house is a muni. They elected to go the underground route. Its in coastal NC. Not outer banks mind you but still in a category 2 wind zone. During Irene the last bad hurricane we had in this area which came through as a category 2-4 storm (conflicting reports) so 120.+ MPH it took our 60% of the customers, highest on record.
Doesn’t sound very hurricane proof to me. Some of it is unless you put the RMUs in vaults you still get rain infiltration no matter how good deals are.
Granted they didn’t have to put in new lines/poles so recovery was faster.
- Status