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Topic Title: Moving a Large Transformer to North Wales.
Topic Summary: A historical film.
Created On: 19 May 2017 10:55 AM
Status: Read Only
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 19 May 2017 10:55 AM
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Zoomup

Posts: 3212
Joined: 20 February 2014

I came upon this very interesting film on YouTube. Look out for no PPE safety gear http://www.youtube.com/watch?v=afvGStYT9xI&safe=active

Z.
 19 May 2017 11:32 AM
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mapj1

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Well, they are not barefoot, unlike some pics I have of folk soldering early undersea cables on a wooden deck with a pot of solder and a brazier of coal.
I reckon the boots will protect against stubbed toes, and the flat cap and cotton overalls protect both against arc, flames and sunburn.

Also you can use a flat cap like an oven glove to pull out a fuse while hot, without your skin sticking to it. I've been told...

-------------------------
regards Mike
 19 May 2017 11:54 PM
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sparkingchip

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Lol.

Road haulage engineers. There's few people who would object to the use of engineers in that title!

Andy B
 20 May 2017 09:09 AM
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Jaymack

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Joined: 07 April 2004

Originally posted by: mapj1
Also you can use a flat cap like an oven glove to pull out a fuse while hot, without your skin sticking to it. I've been told...

I was an electrician in the Scottish steel tube industry, during my early career. When there was trouble at t'mill and the DC breaker for the Pilger mill wouldn't close because of interlocks; one chargehand would bypass these by pushing in the breaker by hand, using his bonnet. He was doubly insulated, since there was a rubber mat along the front of the long, open slate board. The breaker was about 8000 Amp rating!, impressive rising arc when it tripped. The cap was in lieu of the standard wooden stick! Nostalgia indeed.

Regards
 20 May 2017 09:27 AM
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mapj1

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Ha - would that be flying earth earthed DC by any chance, with 2 warning lights centre earthed, so at half brightness when all is well, and one goes out to say you have an earth fault, but you can keep things moving to a safe state ?
Health and safety seems to vary a lot by date and by region. My father, long now retired, started his electrical life a "sparks" (wireless operator) in the Merchant Navy, and has stories of weird things with shore power and ship yard electrics that sound similar. And a tale once of being in the bunk while ashore and the paint on the steel bulkhead beside him suddenly blistering and catching fire. (probably about the year that transformer was on the move) On further investigation a shore team were doing a quick weld repair to a hand rail or something on the other side. Not sure how an incident like that would be viewed nowadays.

-------------------------
regards Mike
 20 May 2017 09:29 AM
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Jaymack

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Originally posted by: Zoomup
I came upon this very interesting film on YouTube.

A similar size to to the transformers at aluminium smelters. One failed after an end blew off, at a porcelain post connector inside the transformer. This 275 kV transformer was one of 4; looking back on the records for the rail movement from Stafford to Invergordon, a chart recorder for acceleration, showed that it had been involved in a shunting accident, the core had shifted.

Regards
 20 May 2017 09:54 AM
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Jaymack

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Originally posted by: mapj1
Ha - would that be flying earth earthed DC by any chance, with 2 warning lights centre earthed, so at half brightness when all is well, and one goes out to say you have an earth fault, but you can keep things moving to a safe state ?

There was a hybrid system, "the newer A.C. system" and D.C. distribution for parts of the plant. The warning lamps were mounted on the wall in the workshop, at one steel melting plant. As an apprentice who rotated through plants, I well remember the shift electrician with a test lamp round his neck, and his labourer (they always had a helper, I think it was a union thing); they would go out in all weathers to chase the fault on outdoor cranes in scrapyards etc.

Regards
 20 May 2017 02:48 PM
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John Peckham

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I wonder what response you would get if you had a time machine and traveled back and turned up on that job with your standard 5 pieces of PPE and asked to see their RAMS?

I like the women walking past the transformer whilst being winched with their handbags over their arms and the kids with their ring side seats. I would think a modern HSE inspector would need to lie down in a darkened room and have counselling for the trauma!

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 20 May 2017 08:02 PM
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sparkingchip

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At the other end of the cables from North Wales is the Feckenham sub station originally built around the same time in the 1960's.

My dad took me and my brothers to see Pickfords bringing the kit in on a towable hovercraft used to stop the road bridges collapsing.

Regards the engineer comment above, at a guess most of the Road Engineers would have been fighting in the 2nd world war rather than going to university or completing recognised apprenticeships, but I bet they knew how to work as a team to throw a Bailey bridge across river or recover a tank or whatever else life threw at them, with manpower being the prime mover.

Andy B
 20 May 2017 08:12 PM
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sparkingchip

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Feckenham 1961 Graces Guide

Andy B
 20 May 2017 08:23 PM
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sparkingchip

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 23 May 2017 01:39 PM
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ArthurHall

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Brilliant film.
I have worked on that very transformer. About 10 years ago the 11kV switchgear was changed and I had to do a 415 shot to prove the transformer differential protection. I had to climb up on the transformer to connect onto the 275kV bushings. I wore a bit more PPE than the guys in the film though.
 23 May 2017 03:17 PM
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mapj1

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Sorry - can I ask, for the benefit of one not quite with the meta-language of the HV team, - were you over-volting it then to check the surge behaviour ? What process does that entail, apart from a trip to Wales? I'm always keen to hoover up information on other folks' bits of the system,

-------------------------
regards Mike
 23 May 2017 05:11 PM
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ArthurHall

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Sorry for the jargon. A primary injection shot injects high current at very low AC voltage along a conductor (cable,circuit breaker, busbar, whatever). Current transformers measure the current and feed it to protection relays and other items where it can be monitored. This proves the ratio and polarity of the CT's and proves the path of the CT secondary current. Google primary injection testing for a better description. However you cant do this with a transformer as the impedance of the winding limits the current, so what we do is a 415 shot, this involves connecting a 415V supply to the high voltage terminals of the transformer and putting a dead short across the LV terminals of the transformer. The current is limited only by the transformer impedance. Some sums allow the currents to be predicted, I think on that job I had about 400A at 415V from a 500KvA generator.
 23 May 2017 06:11 PM
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mapj1

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Thank you - yes I can see this allows you to exercise the windings and calibrate the current monitoring without a full voltage test. And I guess warm the windings up a bit as well.
If it was all simple and resistive then I might expect that at 5% of the primary voltage then a short would give the same currents as a full voltage load that would give a drop of 5%. However I can see how the mix of magnetising and resistive losses conspire to not make that be quite right.

-------------------------
regards Mike
 23 May 2017 07:40 PM
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sparkingchip

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So what's the maintenance regime for a fifty year old transformer? Oil change and tap the welds with a hammer?

Andy B
 23 May 2017 08:25 PM
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ArthurHall

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Pretty much, but you need a special HV hammer. The gaskets get hard and start to leak, bushings get dirty and chipped, ancillaries start to fail, fans, pumps etc. We changed a pair of 275/33kV transformers a year ago just cause they dated from the late 50's I can guarantee the Spanish built replacements wont last 60 years.
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