ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Looming Powercrisis in New Zealand

The CRT is not going to be with us for all that much longer anyway. It's increasingly rare to see a CRT computer monitor and plasma and LCD tvs are fast becomming the only option. Give it 10 years and the CRT will be a museum peice.

I think this stuff is a lot of nonsense. There are far more worrying things out there than powerlines. I've yet to see any evidence that linesmen / power workers have a signifigantly higher rate of cancers. Also, there are FAR FAR more serious risks in a home ... just look under the average kitchen sink to find a vast array of scary volitile cleaning agents etc etc etc...

Powerlines are WAY down the list of risk factors.

Dave,
I agree,
Having worked with HV and EHV lines most of my working life, in most parts with them live, I have never turned up a positive cancer test.
In fact the biggest risk here is from the sun and our ever-decreasing Ozone layer.
I had a melanoma cut out of my left arm 3 years ago and continue to have what is known down here as a "Mole-Map" done every 6 months.
Using psuedo-science to effect a result in preventing future expansion, is just not good

The point is....We shouldn't build houses under power pylons & HV lines. NZ is big enough to keep power lines and houses seperate. Isn't it ?

I'd agree, where avoidable they shouldn't run powerlines too close to homes, but purely for the sake of making the place look less industrial.

The problem is that homes consume electricity and unfortunately you need pylons to provide it! It's a bit of a catch 22.

Mike, may I say firstly that this subject may be better with it's own thread?

I take a pragmatic line, trying to listen to all opinions without getting out of my pram, but please don't shoot the messenger!

Let's look at the magnetic field effect first. If the Earth's magnetic field is say 0.035-0.07mT, and bees, magnetic termites and pigeons among others can sense it, what effect does an ehv line, 14,000 times stronger at over 1T, have?

WHO guidelines for electrical workers exposure is 200mT [milli Tesla's] on a regular basis and up to 2T occasionally. 2T will disorient and cause nausea in some human individuals BTW.
Having said that, studies in the US have shown conclusivly, from statistical evidence, that strong magnetic fields appear to have little or no long term effects on health, and do NOT appear to link to Lukaemia or other cancers, although research continues.

Now to the Bristol University [UK] research. The statistical evidence that they present is that there IS a link between the increased incidence in childhood cancer clusters and the presence of these lines. Their hypothesis is that the corona discharges from these lines release ions which react with pollution particles and gasses in the atmosphere to produce charged nano-aerosols. [ I buy that, I have an air purifier here in my office that uses exactly this effect. ] Further, the research team hypothesises that it is these nano-aerosols that are the problem; that when breathed in, they stick in the lungs and depress the body's natural resistance to certain pre-cancerous conditions, and that they may damage sperm, ova and the first cell divisions in a developing embryo- ie they damage the DNA. That, as I said previously, means that they may have far lower effects on adults in the vicinity. The statistical evidence from the case clusters around lines showed effects up to 600 metres from them, well beyond the range of electro-magnetic radiation. Studies 50 years ago, [and later ones by many others], have detected these corona ions up to half a mile downwind of transmission lines, as they are large enough to be carried in air currents. Co-incidence?

The studies are taken seriously by the UK Department of Health, to the extent that recommendations are in process to limit construction of homes within 250 metres of ehv lines and 110 metres of other lower tension lines, even with the pressing need for more domestic construction in the south of England and lack of land. Those recommendations are not, I assure you, based on the aesthtics of having ugly industrial powerlines spoiling the view out of your lounge window!!

Alan

Can we really compare the stats of electrical workers who spend 8 hours a day next to 11 kV lines to that of people living 14 hours a day under 110 kV lines ?

The latest National radio news re the Auckland power upgrade is now to build the new line but operate it at a lower voltage.

220 kV instead of 400 kV although have the capabilty to increase the voltage to 400 kV later on.

It's amazing that all is still talk and no action.
It's quit warm still and haven't had a proper cold snap yet.

In the UK as far as I have read about it in old engineering books, they thought 20 years ahead. The new lines built there, early 60's, were initially livened at 275 kV but were insulated for 400 kV, so olny a transformer upgrade was require to activate the new voltage level.
People see pylons, cables and strings of insulators,
Usually they complain when new lines are built on bigger towers.
Therefore it makes logic to have a new line semie ready for a new future voltage level although the beancounters will disagree here and only think as long their nose is long.

It will be a lot harder in this day and age with public awareness of possible side effects of the latter.

Regards Raymond

Another story from Stuff.co.nz .

Why on earth would you do a thing like that?.
Talk about doing the same job twice.
At the rate that demand is rising these days, it won't be long before the 400kV system will be needed anyway.
These folks really know how to waste other people's money.

That's limpwristed politicians for us Mike.


By the time they step the voltage up to 400 kV the costs of the 400 kV transformers and associated switchgear would have doubled or tripled too,
Hence another clip on your powerbill,

Keep reading this,

Cheers Ray

As Transpower was doing maintenance on the 110 and 220 kV lines today, I was called out to two substations with stuck tapchangers.
Auckland was on a half day brown power dip, lower voltages hence higher than normal tapchanger positions.

Normal routine tap for 33 / 11 kV subs is position 5 or 33000 Volts,

Laingholm sub T 2 was stuck at tap 5, while T1 was at tap 8 with 30 Amps circulating current between the two transformers, the buscoupler was still closed.
One of the TCOL leavers had a bushing missing so I made one up from a shortened 25 mm crimp link, We had intermittand faults here before with T2 tapchanger.

Atkinson sub required the manual crankhandle to operate the tap from tap 5 to tap 6, then it corrected itself to tap 7.
Just dirty contacts.
The master, follower controls did not operate prior to the dirty contacts.