Pikeys and a stolen substation neutral cable = BANG!!!

[Kirchoff]

Hi,
I heard about this on the news. Apparently all the local residents' appliances blew up due to a voltage spike.

I couldn't figure out at first how this happened? Then I started wondering whether, because the secondary winding of the transformer is a 'star' winding and the centre the 'earth/neutral tap it must have caused an inbalance in one of the legs leading to the voltage surge?

I'm not sure if I'm right as I've not worked for many years (ill health).

Any other ideas?

 

[Engineer54]

Quite frankly, i don't believe a word of what's been reported here. The protective relays would have tripped the system out long before any damage could have occurred!! Unless they had been defeated, by trained technicians. Highly unlikely!!!

Many such instances are generally reported by those that haven't got a clue of what their writing about!! lol!!!

 

[Kirchoff]

You may be right, but they interviewed the residents and filmed their broken appliances. But I do agree in that the media put a spin on everything (if not make up) their stories to create shock value, ala Daily Mail.

 

[Silly Sausage]

Unless they had been defeated, by trained technicians. Highly unlikely!!!

Haha!...BEng(Hons) pikeys!

 

[Knobhead]

I’m not one that normally disagrees with you EN54 but look at the normal protection for a “ring” tee switch. HV O/L only! No REF or secondary O/L other than the local fuse pillar.

Knowing where to make the first cut is important to keep you alive, but it’s not rocket science!

Myself and a few of my mates could make some money out of this

 

[mechelec]

if you remove the star neutral to earth link (low voltage as it is a delta star transformer)at a substation you will then have in effect a floating earth as the centre point of the transformer has no reference to earth. If the three LV phases are balanced then all will be well, but on a distribution sub with multiple domestic customers it is a very very unlikely situation. As would normally be the case the load would be imbalaced and therefore you could have anything from 0V - 400V(declared voltages) seen on either of the three phases. This situation will result in up to 400V seen on appliances with no neutral return path. As we know electricity will always follow the path of least resistance and any electronics circuits with filter circuits will be fried.
Eng 54 you may have different protection on the subs where you are but I can assure you the distribution subs around me have BS88 fuses as protection of the LV feeders (and a few ACB's to individual customers) and these will not clear a fault as described above. The ame situation arrose locally some time ago and meant the removal of all cutout fuses to 250 properties (including breaking in to empty properties with police escort) one poor woman arrived home 30 minutes after they had broken into hers poor thing

 

[Engineer54]

I’m not one that normally disagrees with you EN54 but look at the normal protection for a “ring” tee switch. HV O/L only! No REF or secondary O/L other than the local fuse pillar.

Knowing where to make the first cut is important to keep you alive, but it’s not rocket science!

Myself and a few of my mates could make some money out of this

Ah, if your just talking about an isolated local distribution TX controlled purely by a RMU, Yeah!! But maybe i was thinking along more grandeur lines when talking about a ''sub-station''!! ...lol!!! How much of a length of neutral cable would they achieve in one of those sub-stations?? hardly worth getting out of bed i would think, especially when your putting your life at risk in the process!! ...:nuke:lol!!! :uhoh2:

 

[Engineer54]

Thinking further on the subject, it would also depend on what sort of LV protection they had on the main switchboard in this distribution sub-station. I know many used to have EFF on the main TX LV supply cables, not so sure on the much smaller set-ups though!!!

 

[mechelec]

its all small subs around here. The largest 11KV-400V subs are only 1000KVA

 

[Engineer54]

if you remove the star neutral to earth link (low voltage as it is a delta star transformer)at a substation you will then have in effect a floating earth as the centre point of the transformer has no reference to earth. If the three LV phases are balanced then all will be well, but on a distribution sub with multiple domestic customers it is a very very unlikely situation. As would normally be the case the load would be imbalaced and therefore you could have anything from 0V - 400V(declared voltages) seen on either of the three phases. This situation will result in up to 400V seen on appliances with no neutral return path. As we know electricity will always follow the path of least resistance and any electronics circuits with filter circuits will be fried.
Eng 54 you may have different protection on the subs where you are but I can assure you the distribution subs around me have BS88 fuses as protection of the LV feeders (and a few ACB's to individual customers) and these will not clear a fault as described above. The ame situation arrose locally some time ago and meant the removal of all cutout fuses to 250 properties (including breaking in to empty properties with police escort) one poor woman arrived home 30 minutes after they had broken into hers poor thing

I bow to your experience in this matter mechelec. Yes i'm afraid your right , i am use to a far more sophisticated set up than 3 BS 88 fuses in the package sub-stations we install, on both the MV and the LV side..lol!!! But, i have been in a few of the bigger localised sub-stations in the Essex area, and have seen protective relays in use, on both the HV and LV side.

 

[alanl]

It can happen (blowing appliances). I did a course last year, and on it was an EON employee whose sole job was to repair damage that they, and the copper thiefs have caused.
It wasnt common, but does happen infrequently when a length of copper is taken from a substation that a quick jolt of high voltage goes down the existing 230v lines.
Anything plugged into the mains at the time is usually fried.
We then had a talk about surge protection devices, and they would not help, as the belt of HV usually went down the neutral or earth. Apparently the incoming 100A fuse does not blow either. He says a few houses have caught fire because of this.
Alan.

 

[Justin pearson]

i use to work for transco in the office organising repairs and replacements of the big transformers in powerstations around the country.

I lost count as to how many power stations where broken into and the earth rods where cut and stolen (Very large Earth Rods). I am sure that any SAP's in the forum will tell you how dangerous it is walking through a live power station with anything metal in your hands.

I never saw any fried copper thieves though.

 

[jay sean]

Our company sent us to do the CP course, we went to Drakelow grid, just the humming of the tx and the overhead cables gives you the willies, don't know how the pikeys have the guts to do that.

 

[Knobhead]

Many years ago I went to the EMEB training collage, at that time remote 132KV protection was by fault throwers. Basically a high speed switch would cause a dead short to earth on the centre phase, the primary station would then register a fault and open the OCB to that feeder. OK until the Pikeys have nicked the earth return from the fault thrower, it’s f-all use then. One or two got their just deserts, DOA when the engineers got there!

 

[Justin pearson]

and on a foggy wet evening they crackle, and spit i wouldnt want to walk round them with a step ladder on my sholder. I forget exactly what they told us on our training, in nottingham where they have fake power station training centre is, as it was so long ago now but getting within 1.2m of some of the bits will arc across and give one hell of a packet.