Solar Roof Panels

[dennis]

Do you really think the link won't fuse before the conductor does?

[The Natural Philosopher]

depends on its cross sectionalarea of course.

[tony sayer]

Ah!, very clever Den, perhaps you have the idea that if the fusible link as you think it is fuzes, then that will shut off the lighting current and thus the building or structure will be protected from the destructive pow'r of Jove's bolt!...

Simples eh;?..

[The Other Mike]

The links I've seen are the same material and the same section as the rest of the conductor.

[Matty F]

te:

One of my more challenging jobs was to design and make audio transformers t hat could withstand 33kV between primary and secondary while passing audio from 17 Hz to over 30,000 Hz. This was to stop telephone operators from get ting earache when a 33kV power line fell on their telephone line, which it did quite often. The telephone line ran 500 miles under the 33kV lines, on the same poles. There were also fusible links and other devices that took a bit too long to react.

[RobertL]

Also the ionization of the air (leading to the conducting path and therefor e the lightening) depends on the local field gradient. That is strongest n ear pointy conductors, where the field lines converge, and that's why light ening conductors often have spikes on top.

Robert

[Bill Wright]

that could withstand 33kV between primary and secondary while passing audio

from 17 Hz to over 30,000 Hz. This was to stop telephone operators from getting

earache when a 33kV power line fell on their telephone line, which it did quite often.

The telephone line ran 500 miles under the 33kV lines, on the same poles. There were

also fusible links and other devices that took a bit too long to react.

Why a transformer? Why not acoustic or optical isolation?

Bill

[Rick Hughes]

On previous house .. mine didn't vapourise instantly, it took a lot of energy, blew the telly and burnt a large slot through the cast iron guttering .... it had been simply run down roof tiles, & over guttering by previous owner.

I slept through it, only found out in morning when a large part of telly was the other side of the room.

[tony sayer]

'Tho Furse do a dished one that seems to contradict that idea...

[tony sayer]

That seems quite a wide bandwidth for phone use, unless they were suing them for Audio Broadcast distribution perhaps?..

And that line .. copper for all of 500 miles no fibre radio link or repeaters?..

[Dave Liquorice]

secondary

I suspect a stray "0" crept in...

Why not? It's not that long ago that the trunks is this country where copper., buried rather than up poles though. I suspect this was open wire telephone pairs as well.

500 miles would require loading coils and repeaters but you don't want 33 kV up the input or output of your repeater amps either...

[Matty F]

I made the transformers in 1968. It took me 12 designs before I made one th at worked. Here's the 11th design, that I still use as a door stop:

The final design was toroidal and again potted in epoxy. It seemed to withs tand 33kV between windings indefinitely, but in practice the high voltage l asted only seconds while all the other links were being cut.

There was no fibre optic in those days. This was a power company whose HT l ines ran the length of the country, and toll calls cost a lot so they ran t heir own phone lines under the power lines. The phones needed ringing frequ ency of 17 Hz, and the engineers asked for 30,000 Hz to be passed, which I achieved with ease. It even passed 100,000 Hz fairly well, using a special technique that I discovered in an old electrical engineers handbook. Maybe they had some horrible multiplex requirement as well. My transformers merel y replaced an old design that was insulated with pitch. How horrible they w ere too. The phones may well have had winding handles on! Does anyone have a requirement for high quality audio transformers these da ys?

[The Natural Philosopher]

once upon a time Tony, it was copper all the way to Australia..

[tony sayer]

Right.. Some time ago and a rather more specialist comms app than general use!. Perhaps the extended bandwidth was indeed MUX'ed for remote control and or monitoring...

Like the design stylee;!. A substation was the inspiration perhaps;?...

High quality transformers are still in some demand.

are still around and have been in existence since 1941 bet they'd like to see your HV design;!.. .

Also Lundahl do high performance transformers..

A smaller manufacturer..

[tony sayer]

That was implying copper all the way in one link. Odd that the transformer had to isolate all sections of the line if indeed that requirement was there. I'd have thought just the local ends would be enough....

Still more has come to light ion this now..

[The Natural Philosopher]

I am not sure at all if there was any amplification in the international circuits. There could be a bit of echo. There must have been transformers everywhere,

Do you remember the days of phoning the multi-lingual 'international operator'; who would phone you back when an 'international trunk line' was available and he/she had actually connected you to the last 5 miles via a chain of human operators with patch panels..?

[Matty F]

A pattern was made out of Perspex, and I cast a silicone rubber mould. The transformer sat inside the mould while epoxy resin was carefully poured, to eliminate bubbles. But there always were some bubbles between the outside of the high voltage winding and the core, and at 33kV the transformers failed. So I used toroidal cores and just wound on lots of insulating tape. I was able to test that to 80,000 volts. I used to wind the Variac up until something went Bang!

[polygonum]

When we started to get direct dial international calls it really didn't seem very important to me. I'm sure most of us had no reason to call abroad, most of the time. At least not at the cost they then were.

[tony sayer]

And amplifiers theres only so far you can take audio sigs down a copper cable of that sort of dimension/s...

Err, well .. I must be as olde as your goodself to remember that which I do;!!...

[The Natural Philosopher]

well, we were in those days already a geographically dispersed family. The high cost was hugely beneficial, as 'el madre' had to resolve the conflict between prying incessantly into our lives and the inevitable cost of so doing.