Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Utility poles

blog.plover.com

Post reply on HN
Print view View original

171–180 of 213 posts

Re: Utility poles

#171

Post by Caveman_Coder »

eptil wrote: post #144
Caveman_Coder wrote: post #137

Earlier quoted context omitted.

Do your system operators us GIS to sectionalize lines and troubleshoot transmission/distribution issues, or are you talking about the engineers/planners?

Both sides use GIS to do their jobs. The scada part is a little different since one-line diagrams are all that is needed for that. But the dispatching is all GIS based. We make significant revenue based on accurate maps and good data as well. Just fixing our attachment rental inventory and keeping it accurate pays for all of the GIS system and upkeep with money to spare.

I'm familiar with the SCADA part (I work as an EMS/SCADA devloper), but before my current role I was actually an operator and we used "red-line" drawings in conjunction with the SCADA system to troubleshoot down lines/relays/lockouts/etc. They were all digital for ease of use. On the transmission side of the house we didn't use GIS all that much, but the DOC folks used it as their primary source.

Re: Utility poles

#172

Post by epx »

ThrustVectoring wrote: post #80
blattimwind wrote: post #67

Earlier quoted context omitted.

You can have a two phase power system[1], but two phase generators are less efficient and more expensive relative to three phase – for the exact same reason why power distribution is less efficient and more expensive relative to three phase. [1] two phases in quadrature, which is very different from split phase, which is not two phase at all.

IIRC these designs don't naturally have torque at zero speed like three-phase induction motors do.

Two-phase 90 degrees apart has zero-rpm torque, like a steam locomotive, the problem is that torque is variable. Three phase torque is constant.

Re: Utility poles

#173

Post by dustinmoorenet »

gunzel wrote: post #149
toomanybeersies wrote: post #142

Earlier quoted context omitted.

Is that an American thing? I've never seen 4 lines on a power line in New Zealand unless they're also carrying telephone lines.

I think New Zealand is the same as Australia with 5 wires: the 3 phases, neutral (the central return wire) and earth. Grabbing a random location in Auckland off Street View shows 5 wires: https://goo.gl/maps/wz1W73uWAiz

That just seems odd to me to have a wire for earth... carried above the earth. I can understand having earth wires in houses made of concrete and wood since they have to get to the earth through those materials, but what makes a common earth ground better than just lots of many grounding points? All that wire has got to get expensive.

Re: Utility poles

#174

Post by JoeAltmaier »

dustinmoorenet wrote: post #173
gunzel wrote: post #149

Earlier quoted context omitted.

I think New Zealand is the same as Australia with 5 wires: the 3 phases, neutral (the central return wire) and earth. Grabbing a random location in Auckland off Street View shows 5 wires: https://goo.gl/maps/wz1W73uWAiz

That just seems odd to me to have a wire for earth... carried above the earth. I can understand having earth wires in houses made of concrete and wood since they have to get to the earth through those materials, but what makes a common earth ground better than just lots of many grounding points? All that wire has got to get expensive.

The earth is a pretty terrible conductor.

Re: Utility poles

#175

Post by dustinmoorenet »

JoeAltmaier wrote: post #174
dustinmoorenet wrote: post #173

Earlier quoted context omitted.

That just seems odd to me to have a wire for earth... carried above the earth. I can understand having earth wires in houses made of concrete and wood since they have to get to the earth through those materials, but what makes a common earth ground better than just lots of many grounding points? All that wire has got to get expensive.

The earth is a pretty terrible conductor.

The point of an earth ground is to dissipate the accumulation of static built up. Ground is not connected to the power supply so there is nothing to return to the power company. The earth is the best place for it.

Re: Utility poles

#176

Post by jackhack »

dogecoinbase wrote: post #130
mirimir wrote: post #99

Earlier quoted context omitted.

Yes, PCBs have high thermal conductivity and low electrical conductivity. Also better thermal stability than hydrocarbons. But unfortunately, quite toxic as well. And they tend to be contaminated with dioxins, which are far more toxic. Seriously, PCB/dioxin contaminated oil sold for frying? That is insane. But then, people sometimes adulterate sugar with lead acetate :(

It's kind of astonishing how far people will go in the absence of a punitive regulatory environment. One of my favorite books in Project Gutenberg is this 1820 treatise on the adulteration of foods: http://www.gutenberg.org/ebooks/19031 Everything from copper to make pickles green, to molten lead to clarify wine.

>It's kind of astonishing how far people will go

Indeed it is. This is a widespread practice:

What comes to my mind is the Chinese milk & baby formula "sweetener" (melamine) incident from 2008 with 300,000 victims. 54,000 babies hospitalized! https://en.wikipedia.org/wiki/2008_Chinese_milk_scandal

Related: it was also in pet foods. 1 dog and 9 cats died during "taste test trials" and Petco pulled chinese-sourced products due to 1000 pet deaths. https://www.fda.gov/AnimalVeterinary/SafetyHealth/RecallsWit... it was also implicated in farm animal feed and fish food. https://www.fda.gov/AnimalVeterinary/SafetyHealth/RecallsWit...

yet almost ten years later, Petco once again pulled pet treat due to contamination! https://www.washingtonpost.com/news/wonk/wp/2015/01/06/pet-s...

And if they aren't adding poison, the wikipedia article links to a prior incident where 12 babies died from malnutrition, due to watered-down baby formula.

Such callous disregard for life (human and animal) is beyond comprehension.

Re: Utility poles

#177

Post by spunkles »

"The poles around here all carry ID numbers, and I imagine that back at the electric company there are giant books listing, for each pole ID number, where the pole is. Probably they computerized this back in the seventies, and the books are moldering in a closet somewhere."

Pretty much... I did data entry for 10 weeks in 2006 putting scanned records of wayleaves into a GIS system for Central Networks (a UK based electricity infrastructure company). Basically they had a record of every single pole, pylon etc, and a record of the legal agreement to access the pole for maintenance (a huge number are on private land, like in a farmer's field or your back garden or an office parking lot). All these records had been input into a GIS system by taking the (very) rough map reference and the pole number, putting that into structured fields, andthen everything else was just scanned documents - my work was part of the upgrading of that (which had been done years before) to completely structured data and a very accurate placement on the map. For legal reasons a lot of the original documents are still kept somewhere. Typically these documents outline both the placement, access arrangement and any payments (which may be ongoing) made to ensure access.

Re: Utility poles

#178

Post by junkcollector »

ars wrote: post #51

> There are three because that is one way to change the three-phase power to single-phase, something I wish I understood better. No, that's not correct. Three transformers is for changing 3 phase medium power, to 3 phase regular voltage (for commercial customers). For single phase home customers, you run a single one of those phases along a street and attach center tapped transformers to it. The center tap means from…

Going to be a bit pedantic here but you absolutely can have 0 Voltage. Voltage is the potential energy created by a difference in charge between 2 points. If you have a mass with sufficient free mobile charge, when you inject additional charge into it, it will rearrange the charge within itself to cancel out in injected charge resulting in 0 Volts of potential. This is the principal that a ground connection works on and why you don't have voltage inside of metal conductors, just on the surface.

Re: Utility poles

#179

Post by smoyer »

ars wrote: post #51

> There are three because that is one way to change the three-phase power to single-phase, something I wish I understood better. No, that's not correct. Three transformers is for changing 3 phase medium power, to 3 phase regular voltage (for commercial customers). For single phase home customers, you run a single one of those phases along a street and attach center tapped transformers to it. The center tap means from…

"For single phase home customers, you run a single one of those phases along a street and attach center tapped transformers to it."

True but there are a few variations. And you also have to remember that each of those single-phase lines runs back (at some point to a three phase transformer. One very important facet of creating the single-phase spurs is to make sure the load is reasonably balanced.

Three phase 240 VAC is also cheaply converted to 120 VAC single phase in the same transformer by putting a center-tap into one side of the transformer's delta-connected coils. You will get 120 VAC from that center tap to either of the adjacent hot connections but you'd better not connect anything between the center-tap and the opposite hot connection!

Re: Utility poles

#180

Post by colanderman »

ars wrote: post #89
aidenn0 wrote: post #83

Earlier quoted context omitted.

While the second half of your comment is correct: >> The electrical outlets in your home have two power-carrying prongs. >Only one of the prongs carries power. The other is attached to the earth, and is always at zero volts. Voltages are about potential differentials, so "zero volts" is relatively meaningless without context. The neutral line is required by the electric code to be connected to earth at the electric p…

> Both prongs absolutely carry power. Both carry current . But not power. Power is volts * amps, and the neutral is defined as zero volts (if you ignore the voltage drop). > you can get shocked when working on junction boxes for the neutral line Only from the voltage drop on that wire. It's not the full 120v. (Unless it's cut of course, but that's a whole different story.) > Here you use voltages as a relative measur…

I think it's incorrect to say that a single wire "transmits" power. Both a current and a voltage difference need to be transmitted to transmit power. So it's really the distribution system as a whole (in this case, neutral and hot together) which transmit power.
Post reply on HN