Back in around 1960 the town of Derby had its voltage changed from 210 to
240. I was remeniscing with someone about the project of changing equiment over and recabling some streets.He mentioned that houses then had a fuse on Line and Neutral (which I remember) He also thought that L & N were at 110 v each side of earth. I hadn't come across that before - would it have been the case?
JohnP brought next idea :
I remember both L and N being fused, the only obvious reason for which would be if the supply was 105v to earth - but I am unable to confirm that last point.
+/- probably more likely on early DC supplies
AC had double pole fusing because neither side was reliably connected to earth, and early plugs were two-pin unpolarised.
Owain
Parents' house was built in the 30s. After the change in that part of the world to 240v AC (from previously DC). It had fuses on both line and neutral. Also had two phases incoming - only one used.
I built up some racks for Reuters Moscow, just after glasnost, and I was told that all switches and fuses had to be double pole because the supply was ±115VAC.
Bill
Sort of floating, and the earth not tied to neutral? Seems a strange concept, but I guess it depends on how the sub station was wired up and what the taps on the transformers were. Brian
Back in the days of valve tvs, the autotransformer was used which meant that the chassis was live, So to combat this I got hold of an isolation transformer, and earthed on side of the secondary and used a three pin socket. Problem solved. It occurred to me that this centre earth problem could be cured in a similar fashion. I never did understand, however why Russian tv ran 625 lines but had
6.5mhz video bandwidth. Brian
Isn't that similar to the sort of supply used in the USA? 120V(live) -
0V(neutral) - 120V(live) and out-of-phase.It happens that Jeff Layman formulated :
Yes..
Jeff Layman snipped-for-privacy@invalid.invalid wrote in news:rotect$9fl$ snipped-for-privacy@dont-email.me:
That is what I thought - but I don't believe it was used like that.
The multitude of local electricity suppliers of the early 20th century left a legacy of many different voltages* and frequencies** across the country. Almost anything is possible. The Electricity Board I worked for was still supplying DC in one place into the 1970s.
IIRC:
Yup, 240V line to line, with an earthed centre tapped connection between them for neutral.
Not quite - but it might just be a nomenclature thing. American installs have an earthed neutral, and then two separate lives in antiphase. So L & L either side of E/N. So you get 120V from either line to neutral, and
240V line to line.
Are you sure about that?
To my knowledge Russia used 625 SECAM D/K which had the sound at 6.5MHz and a video bandwidth of 6MHz. The result would be a better picture than the one we had with a video bandwidth of 5MHz.
I have often think it is incongruous that the eye is more sensitive to horizontal detail but in practice many TV systems have lower horizontal resolution than vertical.
Is it correct that fuses on the neutral line were subsequently banned for some safety reason (maybe because people thought removing one fuse was enough)?
Scott snipped-for-privacy@gefion.myzen.co.uk> wrote in news: snipped-for-privacy@4ax.com:
Yes - or if the neutral blew
I had always wondered why volatages where multiples of 55 (or 60) Volts. An old lexicon suggests that an arc light burns well at about 55-60 Volts, therefore these multiples. (I can't quite see how one would run arc lighting in series, but there were number of arc lamps in this book that self-struck, and had magnets and clamps and things to regulate the gap, and feed the carbon rods.)
This book (from 1896 ISTR) also stated that the myth than engineer were more resistant to current than workers had been debunked. The engineers were paid more, and more likely to have better shoes (fewer holes, less hole, possibly rubber soles), hence more resistance to ground, hence fewer accidents.
Thomas Prufer
Edison chose 110V (DC) as best for his lightbulbs. Europe electrified later by when better filaments were available and the Germans chose
220V. (Both voltages have of course migrated up since.)Similarly IIRC Tesla picked 60Hz in the states while AEG picked 50Hz in 'cos of the metric system and it spread from Germany.
But the carbon arc light predates the Edison bulb...
Thomas Prufer
Scott brought next idea :
It was banned, because if only the neutral fuse blew or was pulled, it left the circuit live with 240v to earth.
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