How does the power company matter?

[Line]

In our electrical world there are several ower companies. Each wanting to give their electrical power to yhou. WWhat I want to know is how does it matter?A Lines froma powerplant hooks up with all the circuits. Your houe is linked to many lines and sources. By the time the current has switched and transformed it would have mixed with other companies currents and it would be impossible for 1 campany to be the sole provider of your power.

 

[Tide]

I'm not sure what you mean by "matter" but it's similar to gasoline in the sense that all the gas stations get their product from the same refineries. They negotiate with the refineries for the price and you in turn negotiate with your gas station for the price you pay - although it may not seem like a negotiation to you. (I.e. you choose to purchase at the stated price or you decline!)

Price matters! :)

 

[russ_watters]

No, what Line is referring to is the fact that a person in Philly can buy power from a power company in Pittsburgh, but the actual electrons only ever come from Limerick nuclear plant, just outside of Philly.

The answer (to 'how can they do it?') is that there are regional monitoring stations for the grid, and companies (like the former ENRON) that buy and sell power between power companies. Since the parts of the grid are all connected, all across the country, all that matters at the end of the day is that the totals match up: if company X sold a billion kWh of electricity, then they must have produced or bought from other companies that billion kWh and fed it into the grid.

 

[Line]

SO it's a sommunal thing?

To make you better understand let's suppose there was just 1 power line and my neighbor and I were the only customers on it.. To companies have power plants linked up at the beginning of it. I selected to receive power from compnay A. My neighbor, company B. If company B is also supplying power how can they keep their electricity from coming into my home?

It's not like telephone where you know exactly where the signal came from and ca send it to any place you choose.

 

[russ_watters]

To make you better understand let's suppose there was just 1 power line and my neighbor and I were the only customers on it.. To companies have power plants linked up at the beginning of it. I selected to receive power from compnay A. My neighbor, company B. If company B is also supplying power how can they keep their electricity from coming into my home?

They can't - that's the point. You can't really control where the power you are using comes from, but it doesn't matter as long as the total that a company sells is matched by what they fed into the grid.

 

[Astronuc]

Think of the electrical grid as a big pond or pool of water (and actually it is called a power pool). Let say one is at one side of the pool near a supplier of water, who collects the water and sells it directly to one.

However, if one wishes to buy from a supplier on the other side of the pool, one cannot simply get the water directly. Instead, one arranges for the far supplier to add water to the pool, and the local supplier still gives one the water directly.

It's not quite physically that way, but its close. Basically the generation is done somewhere on the suppliers grid rather than on the local grid, however for one user it's hard to tell. The local utility has to monitor the power purchased from all its users who buy from another generator, and then make sure that other generator supplies that electricity to the local grid.

The local generator will still charge a delivery fee, so unless the other generator (remote supplier) charges a much lower generation fee, one might not save much money.

 

[Line]

WHat's the difference between a supplier's grid and a local grid?

 

[cepheid]

No difference. He was just explaining to you what happens if California (local) buys power from Canada (supplier) or whatever (examples chosen randomly). I think russ_waters explained it really well.

 

[Line]

But anywhow, I wonder what would happen to somebody if they touched one of those highvoltage lines.

 

[vanesch]

Haha, that makes me think of a publicity I had seen, one day, about a device, sold by green activists, that guaranteed to filter out all electricity generated by nuclear power plants
On the box it said something like "guaranteed 99.99% of nuclear generated electricity will be blocked by this filter"

 

[Astronuc]

But anywhow, I wonder what would happen to somebody if they touched one of those highvoltage lines.

One would get severely burned and killed.

Most electricians work on dead lines - no voltage, no current - and that is usually the case with transmission and distribution (T&D) lines.

However, it is a big inconvenience and a great economic loss to take out a high volate line (100's of kV), so special there are special crews who use helicopters to do maintenance work on HV lines. The crew is protected in the helicopter, and the worker who actually touches the line wears a protective metal suit which keeps the electric field outside. While working on the line, the worker attaches a metal cable between the helicopter and power line.

Interesting work.
http://www.helicoptermonthly.com/images/helinas2.JPG
http://www.helicoptermonthly.com/images/helinas3.JPG
http://www.helicoptermonthly.com/images/helinas4.JPG

from
http://www.helicoptermonthly.com/vertical_detail.cfm?CFID=5159069&CFTOKEN=35768558&ItemID=193&CategoryID=18

 

[Integral]

But anywhow, I wonder what would happen to somebody if they touched one of those highvoltage lines.

Birds sit on HV lines all the time, no problem. The problem comes when you get "close" to ground AND the HV line. For the main lines to close to ground can be within 3m of a tower.

The first thing the Helicopter repair/inspection man does is make contact with a long probe, once the helicopter is electrically tied to the HV line work can proceed safely, the inital contact is a hazarous moment. The entire helicopter and crew are then at the same potential as the wire. IF anything happens to bring a different potential ( e.g. a nearby tower or one of the other wires) within a critical range, disaster will ensue.