Mercury-arc rectifier station under threat!

[Alex728]

I signed up (but forgot my index number unfortunately).

Originally Posted by AC/HL

I remember being fascinated by one in a telephone exchange, when I first started work in the dim and distant past. It charged a room full of lead acid batteries each the size of a bath! 801.

It was a telecoms group I was on which showed me a similar one (I sent them the petition link too..)

Many younger people are curious about the original principles and how much technology is advanced.

At work I was discussing with a younger colleague about how our Asterisk Server for our single site is more powerful than the entire UAX13 once used in the village. I found a BT training manual and showed him but TBH much is way over my head - but we found (on his modern smartphone) a youtube video of a preserved UAX13 in operation, which he watched in some awe especially all the battery shelves, the test desk, and the noise the selectors make.

My other friends (as mentioned elsewhere) are eager to get their vinyl record deck up and running in spite of having laptops, ipods etc...

there are new generations especially those who are aware of resourcing issues and environmental impact who do have a lot of respect for the old durable stuff and how things were once made more locally..

[julie_m]

I'll admit I was holding out for the round figure, but since it's gone ..... 803.

[gezza123]

Signed No. 804

Gerry

[RF Burn]

Sorry AJS, I got in at 800.

There was an MAR in the electrical engineering department at Stafford Polythechnic when I was there as a student about 40 years ago. I can still remember the class that included the operation of this fascinating device and I think that I still have the notes that were made during that class stored in the attic somewhere. Watching the bright spot were the arc danced around was mesmerising... you don't get that with a silicon diode!

[Outrun_uk]

Signed 805

[kalee20]

Originally Posted by woodchips

At the risk of spoiling the party, why do we, anyone, want to keep this rectifier station?

It is interesting, for about 3 seconds, to the average person...

I agree completely. However for perhaps 2% of the population, there will be a massive interest. Perhaps for 0.5% of the population, youngsters hopefully,, it may even start a lifelong passion as well as kick-starting a career!

Thus with 98% being interested for 3 seconds, 1.5% for perhaps 600 seconds (10 minutes), and 0.5% absorbed for 1,261,440,000 seconds (40 year working life, I make this an average 6,307,211 seconds interest per person.

That's why I signed!

[Nicklyons2]

Originally Posted by woodchips

It is interesting, for about 3 seconds, to the average person,

That's longer than my attention span for Eastenders but it doesn't prevent the BBC from transmitting it! (sadly)

Originally Posted by woodchips

the scrap value must be almost nothing.

Ah, to know the cost of everything and appreciate the value of nothing. But to be brutal, even the above statement is incorrect; the value of mercury is quite high and in the MARectifier installations I've encountered there has been a very large transformer associated - replete with lots of valuable copper.

Anyway I think they are marvellous and kept Cinemas, Tramways and the London Underground running for decades and, if you look up details of the High Voltage DC ditribution systems in use in Russia, you'll see they're not dead yet.

Nick

[Lucien Nunes]

Metallic mercury is not as valuable as it once was, now that many applications for it have been eliminated, lamps have much lower mercury content and some mercury compounds are recovered and recycled. However in the past many rectifiers were broken up, while in good working order, to get the mercury. That would be unlikely now on an industrial site where there would be a strong preference for the bulb to remain sealed, to avoid the risks associated with handling mercury. The cost associated with safe (destructive) disposal is a definite plus for us collectors, since it now represents a worthwhile saving for them to sell a rectifier as a piece of viable plant and have us remove it using a proven safe method, compared to consigning it as hazardous waste and paying a specialised contractor to de-contaminate it. It is a case where re-using is far preferable to recycling.

At Electrokinetica, we plan to use our rectifiers. We have DC equipment that will need power as well as lots of AC/DC stuff that can be run on DC just for fun. Because the larger recs only reach full brightness with very heavy power throughput, I have a sneaky plan to run a rotary converter in parallel returning the DC output to the AC mains. Then we need only supply the loss power, which on our 100A 3-phase supply will make for some very brightly lit bulbs. Just need to find that rotary converter.

[julie_m]

Depending on how much power you plan to shove back into the mains, the kind of grid-synchronous inverter used with solar panel installations might make a suitable -- though much less interesting! -- substitute in the meantime.

[Mikebay]

Hi Lucien,
And another signatory

[woodchips]

I did say rectifier STATION, which no one has made any justification. Yes, the MAR is a reliable and useful artifact from year gone by, but there somewhat more than one, unlike the Cutty Sark or Stonehenge.

I didn't say get rid of all MAR, just that this one might just be one too many. Keeping involves cost, and that no doubt runs into thousands, for what? Who pays? I am afraid I now have a pretty cynical attitude to museums. My rather nice collection of Creed teleprinters apparently came from Norwich museum, given no doubt by someone who thought they were a valuable industrial artifact worth keeping.

Obviously Kalee20 is a statistician, the average may be 6,307,211 seconds but the median is 3.1 seconds.

Metallic mercury isn't valuable.

The point about the scrap value was that you, if you were interested, could buy the whole place for minimal scrap value. Transformers are £1.25/kg, scrap is £100/tonne, etc etc so you will only need to find £2-3k if you wanted to preserve it. If you do actually want to preserve it then you too need to know the cost of everything, you will be competing with the scrap man, what the value is is up to you.

[Lucien Nunes]

I would gladly preserve the whole rectifier plant but much better it stays in context, because it is one of the very last, possibly the last, in the fortunate position to be outside of a factory situation where typically no support or protection can be offered. I have rectifiers already and will doubtless find more, but their context is lost because I have taken them away from their original sites and purposes.

We are not talking about a major burden or undertaking to conserve this sub. Compared to some other industrial archaeology projects, it's a breeze. For example, at St. Pancras a grade 2 listed water-tower by George Gilbert Scott was moved 700 yards at a cost running to 7 figures, remaining all the while in the shadow of his monumental Midland Grand Hotel. Is the water tower really that precious as an artefact, despite the number of water towers in conservation? Money was found for it regardless, so why should it not be for a rectifier station?

If there were dozens of similar examples you could claim 'we don't need this one' with a clear conscience and perfect logical justification. We could scrap a few prewar TVs without losing anything but needless duplicates. In the field of heavy electrical conservation, things are not this cozy. Many types of 20th century equipment are apparently completely extinct - I cannot trace, even with the help of widely travelled and well-connected engineers, any surviving examples whatsoever. This is a much more extreme situation than obtains even with scarce radios and TVs, thus the consequences of destroying one example are amplified accordingly. Such sleepers as exist, if not already ruined by copper thieves as usual, rarely come to anyone's attention until it is too late to save them from the construction firms who are contractually obliged to destroy them when sites are re-developed.

Hence, when an opportunity arises to conserve a piece of relatively unusual equipment that is known to be in an advantageous situation with local relevance, support and publicity, you take it, because it has above-average probability of giving some return on the investment.

[Hybrid tellies]

Petition signed and posted on FB

[broadgage]

Re post #48, another way of putting a reasonable load on the arc rectifier might be to connect some modern loads to it, taking care that they are suited for DC of course.

Electric heating or water heating might be a possibility, or possibly modern lighting on multi voltage electronic ballasts.

[Lucien Nunes]

Sure, we have some DC-compatible and even some DC-only loads that could be run from the MARs. For example, 1920s Otis lift motors that require 75A at 210V DC, which one or more of the 250V rec plants could supply. OTOH, that is only a very modest load for the larger rectifiers.

My idea with the rotary converter is somewhat hypothetical, but nonetheless if we want to see and hear the rectifiers at full chat, there's no alternative to recirculating the power. The big ECC unit produces 1400A (yes, 1.4kA) at 250V DC - we certainly don't have anything that consumes 350kW nor a 750A 3-phase mains supply to feed it.

The alternative is to rig up a high-current, low voltage supply for the bulbs, leaving the original 400kVA transformer out of circuit, but that is not as much fun!

[brunel]

The Department of Community, Culture and Leisure is pleased to confirm that following a further meeting, arranged by Hon Graham Cregeen MHK, with The Hon Steve Rodan SHK and a newly formed railway heritage group of enthusiasts , including Manx Heritage Foundation, an alternative site has been identified to permanently house the Mercury Arc Rectifiers and associated equipment from the old Laxey Sub Station.

Hon Graham Cregeen MHK, Minister for Community, Culture and Leisure said: ‘I am pleased that as a result of these discussions, a solution has been found that allows the Department to continue vital refurbishment works at Laxey Station, whilst retaining historically important items such as the Mercury Arc Rectifiers.’

Along with other items of historical interest, the Department has agreed with the group that the Rectifiers and associated switch gear will be relocated to what is currently known as the Goods Shed at Laxey Station. The group will also be taking control of a number of artefacts currently housed in the Goods Shed and plans for displaying these will be confirmed at a later date.

Hon Steve Rodan SHK, Member for Garff said: ‘I am very happy to have chaired a meeting with such a positive outcome for the people of Laxey. The Mercury Arc Rectifiers are a popular attraction and I’m delighted that we’ve found a way to keep them on display.’

The group’s spokesman Richard Henthorn, and Pete Geddes MBE, (who will be heading up the technical and engineering side of the project) said: ‘On behalf of the other members of the project group, we are delighted that we have been able to find a solution to save a fantastic piece of railway heritage, along with securing other items of historical importance. This marks the beginning of what will be a very positive relationship with the Department of Community, Culture and Leisure. We are looking forward to working with them on future projects.’

'If anyone thinks that they could be of help to the project, either physically or financially, please contact either myself at henthorns@manx.net or Pete at pete.geddes@manx.net'

'We would like to get started on the project this winter, and have something in place for the public to visit by next season'.

We hope to include an interactive science section, where visitors and groups can learn about electricity, but this will depend on raising funds, and we would be grateful to any sponsors, especially with an engineering or electrical background’.


http://www.iomtoday.co.im/news/isle-...buzz-1-5953579

[Lucien Nunes]

I was just going to post the very same. Thanks to all those who supported the project, the recs might not be in their original building but at least they are on site at the station where they can be shown in context with the electric railway. The extra space in the Goods Shed for other exhibits might turn out to be a considerable advantage. I have been discussing the move with Pete Geddes and they are already getting organised with this. An excellent outcome.
Thanks again
Lucien

[Valvepower]

Hi,

Another one for the petition – number 828.

I have a soft spot for these sorts of devices after building as magnetizer using an ignitron to switch the capacitor bank into the magnetizing head coil.

It was a fearsome gadget with lots of volts and massive amount of energy in the capacitor bank, but it worked rather well – the ignitron gave off a nice blue flash when fired!

Terry.

[MALC SCOTT]

Signed, 829

[Brigham]

I didn't even know that these were scarce. So what do major continuous-current machines derive their power from? Have we gone back to rotaries?