| General > General Technical Chat |
| The US electrical system |
| << < (12/29) > >> |
| Gregg:
It seems that no matter what the local electrical standards may be, there always seems to be ways of making electrical devices work. The larger the demand for electrical distribution built to a given standard, the better the selection and price due to scales of economy. The differences do make for interesting discussion :popcorn: Perhaps a far more interesting topic may be why 60Hz or 50Hz became standard. |
| james_s:
--- Quote from: IanB on June 26, 2020, 05:07:19 pm ---I was curious when he talked about 200 A service in the video, and then he showed a "small" pole mounted transformer which presumably provided the supply. I know those transformers are bigger than they look when they are down on the ground, but I still wondered how many lots of 200 A it could supply before being overloaded? --- End quote --- Those "pole pig" transformers are typically 20-30kVA, often they have the kVA printed right on them. They are big, typically 3'-4' tall and weigh several hundred pounds. They may supply from one house to 5 or 6 houses depending on the logistics, they try to avoid running 240V over runs of more than a few hundred feet. |
| Monkeh:
--- Quote from: james_s on June 26, 2020, 06:24:53 pm --- --- Quote from: IanB on June 26, 2020, 05:07:19 pm ---I was curious when he talked about 200 A service in the video, and then he showed a "small" pole mounted transformer which presumably provided the supply. I know those transformers are bigger than they look when they are down on the ground, but I still wondered how many lots of 200 A it could supply before being overloaded? --- End quote --- Those "pole pig" transformers are typically 20-30kVA, often they have the kVA printed right on them. They are big, typically 3'-4' tall and weigh several hundred pounds. They may supply from one house to 5 or 6 houses depending on the logistics, they try to avoid running 240V over runs of more than a few hundred feet. --- End quote --- ... a 30kVA transformer won't handle a single 200A service. And we're the underbuilt ones?! |
| tooki:
--- Quote from: Gregg on June 26, 2020, 05:45:00 pm ---Perhaps a far more interesting topic may be why 60Hz or 50Hz became standard. --- End quote --- This paper has a quite comprehensive summary of the reasons: https://www.djtelectricaltraining.co.uk/downloads/50Hz-Frequency.pdf |
| james_s:
--- Quote from: Monkeh on June 26, 2020, 06:37:06 pm --- ... a 30kVA transformer won't handle a single 200A service. And we're the underbuilt ones?! --- End quote --- I don't recall anyone saying anywhere is underbuilt? :-// Or do you just like being a dick? I may have been mistaken in the rating so I just went and looked, the (pad mount, underground wired) transformer that feeds my house and I believe 3 others is 50kVA. This is as far as I know the continuous rating at max ambient temperature. A 200A service will *never* be pulling 200A continuously and it's typical to have 300A-400A cumulative in branch circuits off a 200A main, nobody is ever going to load them all up 100% at the same time. I've seen as small as 5kVA, I don't know what those are used for and at least as large as 75kVA. The only transformer of this type I've personally messed with is a 25kVA unit we used to step up 240V to 4800V to power a series streetlighting regulator, it was the smallest 4800V transformer we could find at the scrapyard. Anyway suffice to say whatever we have here is clearly adequate, I've never seen my line voltage lower than 119V or higher than 123V at this house and it's extremely rare for a transformer to burn up outside of damage from a lightning strike. |
| Navigation |
| Message Index |
| Next page |
| Previous page |