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Topic Title: Transformer room design
Topic Summary: Is there a regulation against running gas mains in a transformer
Created On: 01 May 2013 02:41 PM
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 01 May 2013 02:41 PM
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DilwarHussain

Posts: 7
Joined: 31 October 2003

I am working on a project where the contractor has installed a high level cable route and gas main in what is to become a substation. The room will contain an 11kV RMU, HV switchgear and 2 11kV/400V transformers.
Common sense tells me that this is a bad idea and can be very dangerous; however I cannot find any standards/regulations to support this position.
I would be grateful for any help and support you can provide
 03 May 2013 06:32 PM
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ArthurHall

Posts: 741
Joined: 25 July 2008

I don't think you will find any regs on this subject but I agree that it not a good practice.
On the other hand if its a steel gas pipe it will fairly rugged and a room with transformers will have plenty of ventilation so gas leaks will not be a great issue
 03 May 2013 06:48 PM
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OMS

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Joined: 23 March 2004

You could start with The Gas Safety (Installation and Use) Regulations 1998

Reg 18. - (1) No person shall install any installation pipework in any position in which it cannot be used with safety having regard to the position of other pipes, pipe supports, drains, sewers, cables, conduits and electrical apparatus and to any parts of the structure of any premises in which it is installed which might affect its safe use.



It could easily be argued that with regard to electrical apparatus the gas main cannot be used safely - if only from a pespective of putting untrained gas fitters into a HV room.

regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 03 May 2013 08:07 PM
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SKElectrical

Posts: 970
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Originally posted by: SKElectrical

Afraid I can't help with regulations as such. OMS has quoted you something with a slant on 'could be argued'. You're unlikely to find a reg which speaks directly : DO NOT DO XX. Life would be too simple if that's how regs were worded!

I spoke to a friend who designs these rooms and UPS rooms that are either next door or in the same room. He said so long as there was a 'safe distance' - ie outside zone 2 then it was probably okay. He did voice concern over the risk of explosion of hydrogen gases from the UPS batteries (in the event of fault), which in turn would be a disaster if the gas main caught fire?



Can't help you further.
 03 May 2013 10:57 PM
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rogersmith7671

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One of the first things you might find in large industrial boiler rooms are, large industrial boilers. Common sense tells me that this is a bad idea and can be very dangerous, especially if the boiler where to be supplied via a "gas main". However I cannot find any standards or regulations to support this position. Which is presumably why such conditions continue to persist.
It could easily be argued that putting ghastly untrained gas fitters into such situations, might easily upset the sort of highly-strung commentators who seem to resent the achievements of others however humble compared to their own.

Regards
 04 May 2013 07:51 AM
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eclipse

Posts: 163
Joined: 03 November 2006

If there was ever a problem with the gas main then access is indeed going to be a problem if the sub is owned by the local DNO.
DNO's do not like untrained people working in their substations, and this concurs with commments as made by OMS, if it was a privatly owned TX then its a different ball game regarding access, but still an issue with untrained personel.

We have had a similar issue last year and the DNO told us that they would not alow other equipment apart from their own being installed in the sub as they take ownership of the sub and the equipment inside.

Hope this helps.

-------------------------
Thanks

Alan.

Now what was that reg no?
 04 May 2013 10:27 AM
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alancapon

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Assuming that the substation will belong to the DNO, have you asked them? It is conceivable that they will refuse to accept the room with other services running through it, leading to you not having a supply of electricity available. Often, the only thing allowed is lighting / fire alarms from the building supply, and often a socket or two. Substations are usually built to contain a small explosion due to a flashover, or at least direct the blast into a non-occupied area. I don't see a gas main in the room being compatible with this.

Regards,

Alan.
 04 May 2013 11:56 AM
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slittle

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Originally posted by: alancapon

I don't see a gas main in the room being compatible with this.



Regards,



Alan.



Nor do I but on the plus side it would save the repair of a damaged transformer as there may not be a building left around it.

We wouldn't allow gas mains through any intake rooms so I can't see it being appropriate in a sub.

Stu
 04 May 2013 12:09 PM
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rogersmith7671

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Quote, (INFORMATION TO ASSIST THIRD PARTIES IN
THE DESIGN AND INSTALLATION OF NEW
SECONDARY SUBSTATIONS FOR ADOPTION
OR USE BY SSE POWER DISTRIBUTION);

"The developer shall seek formal confirmation of the adequacy of the design of the site regarding security risk assessment from the SSEPD Planning Engineer."

With the exception of the GRP Enclosure and Padmount Transformer, all
other designs shall be forwarded to the SSEPD Civil Engineering Section
for comment prior to construction. This process will ensure that items such
as clearances and ventilation etc. are correct before construction is
started.

It is fit for purpose. Generally this means complying with Energy
Networks Association (ENA) Technical Specifications and usually
passed ENA assessment.

Adequate training is provided

Each proposal is considered on its individual merits for suitability of
connection to the SSEPD Network. This may result in rejection of the
proposal should any of the above not be complied with.


A certificate of commissioning and handing over shall be provided and
accepted by a representative of SSEPD. SSEPD document FO-PS-110
shall be used for this purpose.

I suspect similar requirements exist for a DNO near you.

Link;

http://www.ssepd.co.uk/uploade...condarySubstations.pdf

Edited: 04 May 2013 at 12:21 PM by rogersmith7671
 05 May 2013 11:51 AM
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DilwarHussain

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The substation is to be owned and maintained by Netwrok Rail, the DNO has provided HV supplies in and RMUs in separate rooms which they have accepted into use.

Thanks for all your help guys, I have sent this back to the contractors asking them to demonstrate future maintenance and or replacement can be done safely and to seek NRs buy into the installation


Regards,
 26 January 2016 02:29 PM
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emmanuel

Posts: 10
Joined: 18 January 2003

Sorry to revive an old thread, but it seems along the same lines...

I am looking for a standard or guidance note covering the need for trenches or bund walls to mitigate against oil spilage and fire risk?

The local authority here only have approved designs for substations that are externally facing, in this case I have a client owned substation which is internal to the building, and I am worried about a tank rupture and subsequent spread of oil to other parts of the building and the associated fire risk?

The local authority do not seem concerned and have said it is not required, but I think it is. So looking for some guidance or typical details?

Thanks
 26 January 2016 02:39 PM
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emmanuel

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Sorry, also wondering if (aside from good practice) there is any actual requirement for separation of rooms for LV switch/ TX / MV switch - or combination thereof
 26 January 2016 02:57 PM
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perspicacious

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The local authority here only have approved designs for substations that are externally facing, in this case I have a client owned substation which is internal to the building, and I am worried about a tank rupture and subsequent spread of oil to other parts of the building and the associated fire risk?
The local authority do not seem concerned and have said it is not required, but I think it is. So looking for some guidance or typical details?


I would imagine your client's insurers would have an interest in this, as would your local fire authority emmanuel..

However, if you were to contact them and they impose costly works onto the client, you won't be very popular.

I'd write to the client with my concerns and get him to ask his insurers/local fire authority for their requirements.

Regards

BOD
 27 January 2016 10:28 AM
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emmanuel

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Thanks perspicacious - in terms of how to tackle it, you are right, what I am trying to establish is what is prescribed - I recall NEC require pits etc, in terms of BS EN I am not sure?

So when installing on an existing slab, what are the guidelines? bund wall? or dig it up and create a pit? or?

Thanks
 27 January 2016 02:01 PM
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AJJewsbury

Posts: 13736
Joined: 13 August 2003

The local authority here only have approved designs for substations that are externally facing, in this case I have a client owned substation which is internal to the building

What to see what Alan C or OMS have to say - I'm slightly worried as I understand that conventional substations are designed with roofs that can blow off as under certain fault conditions the transformer (or HV control gear or something) can expolode in a quite spectacular fashion - so the roof is sacrificed to allow the blast to dissipate. Sticking such a thing within a building without any blast route to the outside sounds a little worrying to me. (That might even explain why the standard designs don't cover such a setup).

As for the bunding problem - are oil-less transformers available these days?

- Andy.
 27 January 2016 03:55 PM
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alancapon

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I wouldn't see too much of an issue with the oil (depending on quantity) as we are usually talking about a small amount. You could easily construct a small bund if you are worried. Of more concern is the effect of a flashover which will pressurise the room - this can lead to structural failure if the room is not large enough, leading to lost doors / walls / roofs. Obviously with a substation in a building you need to ensure that it vents into an unoccupied space and does not cause structural issues for the rest of the building.

Regards,

Alan.
 27 January 2016 09:09 PM
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mapj1

Posts: 6582
Joined: 22 July 2004

By way of an example, the tranny room at my place of work is on an outside corner ground floor of a 2 story building, and the pillars that hold the rooms above are enormous, and the external facing 'curtain wall' between them is very thin - it looks like a very deliberate 'tear here' design compared to the rest of the building around it.. Its less than a megawatt, but it is the best of 1972 or thereabouts so who knows if the designer was listening to Mungo Jerry at the time..

-------------------------
regards Mike
 27 January 2016 09:36 PM
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alancapon

Posts: 6276
Joined: 27 December 2005

The size of the transformer is not relevant in the calculation. It is the available fault current and clearance times that determine the expansion of the air inside the substation with a flashover.

Regards,

Alan.
 27 January 2016 09:45 PM
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OMS

Posts: 20906
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Fire and blast would be my primary concerns followed by environmental damage

Transformer size (rating) will determine the oil quantity - you might be able to mitigate with a hermetically sealed transformer and Midel fluid. Obviously a cast resin dry type would be a better choice

Blast is not associated with size - it's a function of fault energy levels - even a low rated 800kVA transformer might well have 350MVA fault level available on the primary side - and that could easily be on 1 second (or 3 second) disconnection

If you are sure that you have really robust construction and a suitable low resistance blast route (or a mahoosive transformer room) then that may be acceptable

Basically though, it's the design thinking that manage fire and blast that will determine the solution

Personally, I wouldn't put a fluid filled transformer in a building (unless it was a dedicated stand alone substation building built for purpose

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 27 January 2016 09:50 PM
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mapj1

Posts: 6582
Joined: 22 July 2004

Fair enough, but the available LV fault energy is likely to be more on a big supply of many MVA than say one hundred kVA, just due to transformer regulation. Or do you mean would the available HV fault dominate in any case ?
Actually thinking back to my time at the University of York we had a transformer fire there indoors in the electronic dept building, fire brigade called and everything, must have been about 1995 or so - no bang, but very impressive smoke ..

-------------------------
regards Mike
IET » Wiring and the regulations » Transformer room design

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