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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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15th Jan 2019, 12:03 am | #61 |
Dekatron
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Re: Switched or Unswitched Sockets for HI-FI
Final ring circuits cause interference to inductive loop hearing aids, I would not be surprised if auditoriums were wired with radial circuits to appease that outdated technology.
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15th Jan 2019, 1:15 am | #62 |
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Re: Switched or Unswitched Sockets for HI-FI?
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15th Jan 2019, 1:23 am | #63 | ||
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Re: Switched or Unswitched Sockets for HI-FI
Quote:
My purging resister can be seen in use soak testing a power supply following a repair. Then there is where the bad electrons ended up taking short cuts. |
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15th Jan 2019, 10:40 am | #64 |
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Re: Switched or Unswitched Sockets for HI-FI?
Any idea whether that pole was caught in a fire or struck by lightning?
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15th Jan 2019, 10:57 am | #65 |
Dekatron
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Re: Switched or Unswitched Sockets for HI-FI?
That is curious! The shroud round the HV cables, and the cables themselves, looks fresh, i.e. no apparent soot or scorching- surely, new cables wouldn't have been installed on a markedly charred pole? Or maybe it was deemed "OK"? Makes me wonder if the burning of the pole was a result of the previous old cable deteriorating and becoming a pyrotechnic device, and the bean-counters said "minimum expenditure".
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15th Jan 2019, 1:02 pm | #66 |
Dekatron
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Re: Switched or Unswitched Sockets for HI-FI?
What actually happened is that all the grumpy electrons gathered in the 100 amp drop cable and eventually there was one of those really hot summer days and the electrons rioted.
The bean counters had been at work however technology advanced fast and got ahead of them and it all went off What you see is the carbon footprint of renewable energy. They did there ohms law before they replaced the cable. |
15th Jan 2019, 1:23 pm | #67 |
Octode
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Re: Switched or Unswitched Sockets for HI-FI?
Although it sounds like Refugee is taking the ****, it would most likely have started with the tar in the wood migrating south to earth, resulting in an electrical path to earth.
Similar happened a few years ago at the back of the garages, they ended up re-wiring the overhead lines with black plastic wiring, 6 core of course. They had enough of all the reports of sparks flying, literally! I'll leave Refugee to mingle with his electrons. Rick. |
15th Jan 2019, 1:52 pm | #68 |
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Re: Switched or Unswitched Sockets for HI-FI?
Do your ohms law on the 7.5 MW at 11,000 volts.
The old cable was 100A and fed a stud farm. They just quoted to plug in and by the time they got the go-ahead for the square footage of panels the only ones in stock were double the output. They just fitted them and then turned them on and billed for their money during a spell of cloudy weather and went away happy. With the overloaded cable on the south side of the pole and a bright sunny day it went bang. |
15th Jan 2019, 2:45 pm | #69 |
Octode
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Re: Switched or Unswitched Sockets for HI-FI?
Yikes, now I can see what happened, it sounds like gross overloading being fed to the power lines.
Is the pole 3 phase? What would the chance be of the panels throwing out the phasing if it is 3 phase? Some houses in our village have roof panels in varying numbers, apparently it has something to do with balancing the load between the phases, from what I've been told, whether that's true I don't know. To be thruthful, I have very little clue how any system works, with the exception of single phase. Rick. |
15th Jan 2019, 3:02 pm | #70 | |
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Re: Switched or Unswitched Sockets for HI-FI?
I thought that Ohms law was just to do with volts, amps and ohms, not power. Never mind, a big oops (a nearly seven times big oops).
Quote:
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15th Jan 2019, 5:31 pm | #71 |
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Re: Switched or Unswitched Sockets for HI-FI?
The solar panels have a 10khz inverter to three phase so they will produce a chopped output that is filtered through a set of chokes to the cable. they will always produce a balanced output. They sound like a giant 405 TV when it is sunny.
All you need to do is divide the 7.6MW by 3 times 11.000 volts and you get enough amps to roast the 100 amp drop cable that was there before it went bang. I doubt of a domestic solar system would produce enough power to put a system off balance. |
15th Jan 2019, 5:53 pm | #72 | |
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Re: Switched or Unswitched Sockets for HI-FI
Quote:
Al. |
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15th Jan 2019, 6:22 pm | #73 |
Octode
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Re: Switched or Unswitched Sockets for HI-FI?
Please tell me if I've worked the figure out, a calculator has shown more than 200 amps.
My maths is useless for most things. Rick. |
15th Jan 2019, 6:24 pm | #74 |
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Re: Switched or Unswitched Sockets for HI-FI?
That's it, I am getting a rotary converter, AC to AC with a long insulated shaft twixt the two, perfect mains. With all that whirring and humming I won't notice any imperfections in the HiFi.
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15th Jan 2019, 6:50 pm | #75 |
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Re: Switched or Unswitched Sockets for HI-FI?
Supposedly, (watching one of bigclive's videos) they had a similar problem on the Isle-Of-Man, with the rather nice summer one of their solar farms generated too much electricity was being generated and they actually had a transformer blow.
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15th Jan 2019, 10:23 pm | #76 | |
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Re: Switched or Unswitched Sockets for HI-FI?
Quote:
Voltage of 11 kV = 11 x 10^3 volts. Current = Power ÷ Voltage (assuming unity power factor). So, Current = (7.5 x 10^6) ÷ (11 x 10^3) = (7.5 x 10^3) ÷ 11 which = 7500 ÷ 11 = 682 amps. (to nearest whole number). And that is a helluva lot of current! - which will require some really serious conductors. I'll illustrate that: Suppose the total resistance is 0.01 Ω. Then the power dissipated in that resistance is 682 x 682 x 0.01 watts. That is approx. 4650 watts! If the R is 0.001 Ω, the dissipated power then becomes 465 watts. Even that is a substantial amount of lost energy - and conductors of 0.001 Ω are going to be really thick - yes, all of them! Al. |
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15th Jan 2019, 10:25 pm | #77 |
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Re: Switched or Unswitched Sockets for HI-FI?
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15th Jan 2019, 10:52 pm | #78 |
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Re: Switched or Unswitched Sockets for HI-FI?
Isn't some adjustment to your figures needed on account of it being a three phase supply?
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15th Jan 2019, 11:13 pm | #79 |
Octode
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Re: Switched or Unswitched Sockets for HI-FI?
Just read that equation and got lost in transtation!
After looking at the last figures, Graham has a good point, it appears it's for single phase. If the figures are divided by 3, it'll be somewhere near 200, if that makes sense. Rick. |
15th Jan 2019, 11:14 pm | #80 |
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Re: Switched or Unswitched Sockets for HI-FI?
Yes indeed Graham. 11kV is the line-line voltage (it's delta, there's no neutral) so the current would be:
7.5M / 11k / sqrt(3) = 394A at unity pf. At the other end of the spectrum, primary batteries were mentioned upthread as a comically unsuitable way to power a HiFi amp. It has been done, in a commercial product. IIRC at least one reviewer found the amp rather lacking in power... |