Buried SWA cable fault finding

[marconi]

Is this a "continuation" of your suggestion in post #25 in that you require this pulsating system.?

Yes

 

[pirate]

I truly don't understand this at all, but I'd love @marconi to wire my Christmas lights!
Seriously, I love to try and follow the logic, but the theory is way beyond me. However I also love to see the ideas out there! Thanks,!

 

[marconi]

#62 reminds me of our Glaswegian lecturer in electrical engineering science, who if you interrupted him during a lecture and asked him a question had the stock answer - 'd'ya knaw listna tu ma lecktures?' - and then he carried on with the lecture.

(With apologies to all Glaswegians for any failure to represent in italics how he said it).

 

[Lucien Nunes]

I'd probably cheat and use AC, having checked what error the cable inductance is likely to cause (top of head it's very small.) Wrap a couple of turns of 16mm through any hollow-centre toroidal transformer to make a secondary and wind it up on a variac, or ballast the primary with a suitable lamp. Any decent pot to make a bridge, use multimeter to find the null then read off the pot resistance ratio out of circuit.

Of course it would be better to fetch the bridge test set but that's far away in deep storage.

 

[timhoward]

@Lucien Nunes in my vast pile of junk I'm sure I have a post-office test box. I acquired it as a curious item that looked nice and never twigged it's purpose, but this thread suddenly resulted in a light-bulb moment and I realised that all along I had a bridge in a box without realising it.
In theory, assuming I find it, would a DC multimeter work instead of a proper galvanometer?
It's a bit like this one (from memory)

 

[marconi]

Work in progress.

 

[marconi]

Power on trial without electronics. Electronic control finished and to be connected to board next.

 

[telectrix]

in my cave i have a bridge megger. could this help . it's finer functions are beyond my old brain these days.

 

[littlespark]

I’ve got a couple of bits of bent fence wire… does the trick…

Sorry, that’s for water

 

[timhoward]

in my cave i have a bridge megger. could this help . it's finer functions are beyond my old brain these days.

Noting @pc1966 's comments earlier in this thread about the Varley test's shortcomings, yes, I recently discovered the Megger Bridge series were designed to conduct Varley and sometimes Murray tests. Is it either of these: