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lance4k
27-07-2006, 01:18 PM
Ok i have a standard hot water cylinder at my house, if I used up all the hot water from it,does to hot water cyclinder use MORE power to heat the stone cold water back into hot water? And once and hot water has reached the correct temperature does it go into a kind of standby mode where it uses LESS power then when it's heating cold water to hot water?

godfather
27-07-2006, 01:25 PM
Its just like your electric jug, except it has a thermostat and should be well insulated to reduce most of the heat escaping out the sides..

When the water reaches the desired temperature, the thermostat switches off the power to the element. As the water slowly cools a bit, the thermostat will cut in, allowing the element to heat it up a little bit again so its always at the right temperature.

The power used is dependent on the power needed to raise incoming cold to the set thermostat temperature. Use a little hot water, the overall temperature drops, the element comes on for a while.

Use a lot, the element comes on for a lot longer.

Power use is directly proportional to water running out the hot tap.

Add to this that it may also be dependent on what tariff you are on with your power company, they may stop the element coming on at peak times, the re-heating will be delayed until off-peak.

Graham L
27-07-2006, 01:28 PM
The amount of energy needed to heat water depends on the quantity of water, and the temperature difference required. There is always a bit more needed, because the water isn't held in a lossfree container. You have to heat the cylinder (which is why cylinders always used to be made of copper --- its "specific heat'[ is small), and the insulation.

When the water is up to temperature, the only energy used (as long as there is no draw off) is that needed to replace the losses through the insulation to the outer shell (where it is lost to the air), and any losses through conduction to the pipes.

lance4k
27-07-2006, 01:34 PM
so here a 2 scenarious:

1)i use up all the hot water each day and the water is stone cold.

2)i DON'T use up all the hot water each day(say i only use half of the hot water)


What scenario would use the MOST power each day?

And how much approximate power do hot water cyclinders use per month on scenario 1 and scenario 2?

godfather
27-07-2006, 01:41 PM
1) The amount of power depends on the amount of hot water used (the amount of water running out the hot tap)

2) As above but if its the same cylinder, and you have only used half the heated water it will cost half as much as heating it from cold.

We don't know the cylinder size, so we cannot tell you how many units it would cost to completely heat a stone cold cylinder.

Again I repeat, the cost is directly proportional to the amount of water you use. There is no magic involved.

Terry Porritt
27-07-2006, 01:42 PM
Try taking a cold shower each morning, it has a remarkable curative effect on the brain cells:
http://www.associatedcontent.com/article/43477/cold_water_therapy_cold_showers_arent.html

Graham L
27-07-2006, 01:55 PM
Say you've got a 200 litre water cylinder.

Ignoring the losses:

to heat 200 kg of water from 10 degrees C to 60 degrees will take 50x200 000 calories, which would be 4.184 x 10^7 joules, which comes to 4.184/3.6 x 10, 11.6 kWh. I think that's right. ;)

If you use only half the water each day, you will use half that much electricity to heat it.

Add a bit for the losses. If you use all that water in one long shower, you will lose less heat to the pipes. If the pipes cool down and have to be heated again you lose more. You pay to heat the cold water in the pipes which comes out when you first turn on the hot tap, remember.

Metla
27-07-2006, 01:57 PM
Bugger that, Buy an on-demand water heater.

godfather
27-07-2006, 03:27 PM
11.6 kWh. I think that's right. ;)

11.67 kWh according to me, but I am not the pedant here...



Bugger that, Buy an on-demand water heater.

The on demand (electric) waterheater will use 11.67 kWh as well. Just no ongoing storage losses, but then the tariff is usually higher in c/kWh as its "uncontrolled load".

Cheap answer - don't shower.

SKT174
27-07-2006, 04:07 PM
Those on demand gas water heater are the best ;)

Graham L
27-07-2006, 05:50 PM
11.67 kWh according to me, but I am not the pedant here... My calculator gives 11.62222222. I gave only one decimal digit because, as I did say, you need to " Add a bit for the losses." The losses are significant. Perhaps I should have said "about 11 or 12 kWh". But it might be even more. Do you use inflation adjusted calories?

godfather
27-07-2006, 06:01 PM
I converted from MegaJoules.

You probably forgot the harmonic content in the mains that does not get measured accurately yet does add to the energy delivered?

Graham L
27-07-2006, 06:13 PM
I used the exact conversion factors from calories to joules to kWh. ;) Perhaps you had binary "megas". :D

I don't think the harmonic component will make any difference. If it adds to the total current, the meter will register it.

But the losses are going to make a bigger difference, and you will certainly pay for that. And pay. And pay.

Pato
27-07-2006, 06:34 PM
As there are people on here with knowledge of the Hot Water cyclinder can you tell me if it is necessary to release the pressure valve on top of the cyclinder?. I was told it had to be done every six months then I was told that that is rubbish. Any comments please?.

Graham L
27-07-2006, 06:41 PM
Oh dear, Pato. There was a long thread on this subject a while ago.

That is a safety device. The manufacturers say you should test it every six months. That's to give some confidence that the valve will actually operate if it is ever needed. That would be if you have a big surge in pressure in the water mains, or if the thermostat failed so the cylinder started to be a steam boiler. A bursting cylender is not a good thing. If it is full of high temperature water which flashes to steam as it escapes, it's a very nasty thing.

I'd be inclined to test it.

Pato
27-07-2006, 06:47 PM
Thanks Graham, I never saw that thread and I apologize for not doing a search. I completely forgot. Well I appreciate your comments and I wondered why it should be done and now I know. Again many thanks.

godfather
27-07-2006, 07:49 PM
I don't think the harmonic component will make any difference. If it adds to the total current, the meter will register it.

But the losses are going to make a bigger difference, and you will certainly pay for that. And pay. And pay.

You assume Ferraris disk meters will measure harmonics? They do not perform at all well in that repect, sad to say.

Most electronic meters will to some extent but the vast majority of metering is still Ferraris.

In a holiday house just purchased this year, I noted the cylinder cupboard was a bit warm. The pipes to/from the wetback fire and the outlet were uninsulated, so I fixed that and the cupboard temperature now barely rises. Must have cost someone thousands in losses over its life to date. And no, It's not also thermosyphoning when the fire is not going...

Stephen111
27-07-2006, 08:44 PM
I assume that in your enquiries the objective is to 'Save Money' on the energy you buy heating your Hot Water.

The smart way to save $$$$ is:

- Buy a Solar Hot Water System (with storage cylinder - and you might be able to use your existing cylinder) for base load heating - designed and based on your demand (most people who supply these services will be able to help you out e.g. cylinder size, collector area size)
- Back your system up with Instant Gas (lpg bottles often more economic due to lack of need to pipe from the street) for peak load demand and / or off peak sun supply (cloudy days, winter etc)
- Get Quality Insulation on Hot Water Cylinder and all pipes
- Get a really good installer
- Most suppliers around the western world will tell you you'll save up to 75% of your energy cost on heating your hot water per year (way better than instant gas that is just cheaper than electricity) = $$$$ back in your pocket, despite the initial investment - many of these last 10 to 20+ years.
- Just search google for a supplier.


Good Luck

S.

SurferJoe46
28-07-2006, 06:46 AM
1) The amount of power depends on the amount of hot water used (the amount of water running out the hot tap)

2) As above but if its the same cylinder, and you have only used half the heated water it will cost half as much as heating it from cold.

We don't know the cylinder size, so we cannot tell you how many units it would cost to completely heat a stone cold cylinder.

Again I repeat, the cost is directly proportional to the amount of water you use. There is no magic involved.

The IS some voodoo involved however, Graham, and it looks like soapbox time........

The heating of water is not a very cost-efficient process, even under max conditions. Raising water to a certain temp from a baseline of say, room temp is always more energy wasting that is imagined.

Keeping the temp at a set value (maintained) is not efficient either. I will say why a little later if you ask.

Electric heating is by far the most costly in all cases; direct fire is the best and the higher the BTU's of the fuel, the better.

I was always amazed that the cost per gallon of heating water rose with the temp required and the volume. Going from, say, 180F to 205F cost as much as going from 206F to 212F (boiling on the F scale). The costs are non-linear and losses are great at the higher temps if they are not associated with pressure rise. At 1 atmosphere, the losses were greater than at 10 atmospheres.

The trick is to not allow boiling. The rise in energy to get that last degree to the rolling boil is a big spike in energy use. The same with freezing water.. ....that last degree to change from a slurry to actual ice takes a lot of energy to achieve. This was quantified by Nicolas Léonard Sadi Carnot.

The curve is still there at lower temps and pressures, just not as obvious, but wasteful in the long run.

Sometimes the representation of "boiler efficiency" does not truly represent the comparison of energy input and energy output of the equipment.

Remember, the initial cost of a boiler is the lowest portion of your boiler investment. Fuel costs and maintenance costs represent the largest portion of your boiler equipment investment. Not all boilers are created equal. Some basic design differences can reveal variations in expected efficiency performance levels. Evaluating these design differences can provide insight into what efficiency value and resulting operating costs you can expect.


Every boiler operates under the same fundamental thermodynamic principles, therefore, a maximum theoretical efficiency can be calculated for a given boiler design. The maximum value represents the highest available efficiency of the unit.

If you are evaluating a boiler where the stated efficiencies are higher than the theoretical efficiency value, watch out! The efficiency value you are utilizing may not truly represent the fuel usage of the unit.

This is why steam generation for institutional heating and power is done with boilers that run at 200lbs/pressure, and 300F degrees. The losses at lower temps and pressures are too great.

Needless to say, keeping the water heater at a lower temp will reduce the energy used and lower the overall cost too. It's not a linear extrapolation no matter if the container capacity is large or small.

The following values are the peak of efficiency for a given boiler design, and by laws of thermodynamics are the highest achievable:


Pounds Per Square Inch Degrees Absolute (psia) to temp Fahrenheit (°F)


11 - 198
14.7 - 212
110 - 335
340 - 429
630 - 567
1200 - 596
2000 - 636
3000 - 695
3206.2 - 705.40


The energy advocates here in the US recommend setting the temp at 145F instead of 160F for a more than 20% energy savings with just a 15F degree difference.

Use of electricity to heat water is frowned upon because of the multiple energy conversions and transmissions that are required to make it ultimately heat water. Each conversion involves losses that are wastefull to say the least.

OK...I'll pop in the reason to NOT keep the water at a set temperature:

I know that most people feel that keeping the heater at the same temp is efficient. It is not.

During the night when electricity usage is minimal after midnight or so, the cost of power generation goes down. Your homes and most factories shut down to minimum usage of energy, and the result is that you don't have the high spike fee values.

It works like this:

Energy use is computed on the peak current used by a building/home..etc.

If you turn on every appliance at the same time, you get an energy use calculation that is based upon that consumption for (in the US) the next 8 hours. This is why major users of heavy equiptment are warned to turn on the high-amp units first. This will peak the meter at a lower rate that if they turn on all the peripheral devices and then the high user. Electric motors and heaters going from cold will always draw deeply (peak demand) from the source and then they will settle down to a lower consumption.

You would be wise to allow the heater to run a little hotter at night when the total amps draw for the building is lower and therefor, a lower meter rate.

You'd also be banking hotter water against conversion from a lower temp later on in the morning when showers and hot water usage is higher, using less of the hotter water to acheive human requirements for a hot shower. Allowing the thermostat on the boiler to be lower during the day will help lessen the total amps used for a lower bill.

See?

godfather
28-07-2006, 12:52 PM
Joe

Only about 20% of domestic houses in NZ have a time-of-use tariff, residential customers do not have a "spike" (demand) fee anywhere in NZ at present.

Thermostats in most NZ houses are set to less than 75°C, as a norm (depending if the owner has had a fiddle with it). Newer cylinders are "Grade A" that have a very high intrinsic level of insulation with minimal losses, our one here has no warmth at all detectable on the outer skin. The output is tempered by a mixer in newer houses to premix with cold to deliver a lower temperature (using less of the hot water stored) for safety at the tap.

The electric storage waterheaters here usually fall into two main camps, those heated on a controlled rate where the power company shed the load at their system peak times, and those that operate only on off peak (night) rates. Ripple control is used.

180, 270 and 300 litre capacites are the common sizes.

Higher temperatures do result in higher losses if a poorly designed cylinder is used, but its less of a factor with a correctly designed one.

Electricity as an energy source cannot be "destroyed", it can only be converted to heat, light or motive power. Losses are heat, but just not useful heat. Boiling produces steam which is vented and heats the atmosphere and agreed must be avoided in a domestic cylinder.

Hot water heating accounts for 40% of all domestic load on average, where the water is heated by electricity.

Graham L
28-07-2006, 04:30 PM
So to reduce electricity costs, you need a means of causing harmonics. Harmonics will drive resistive heating elements, so if they won't register on the meter ... :D

Joe: our domestic water heaters boil only if there's a serious (thermostat) failure, or if a "wetback" (a heating coil in a fireplace) adds too much heat to the water. My only mention of steam boilers was in reference what can happen in the fault case. That questioner was asking about the pressure relief valve on a "mains-pressure" cylinder ... which could be a seriously dangerous device. It's at 100 psi or so normally, so the boiling point is high. If no taps are on, a thermostat failure could produce a dangerous pressure increase. So there's a pressure relief valve. Older cylinders are fed from a header tank, and have a vent pipe open to atmosphere The maximum possible pressure is about 10-20 ft water gauge ... say 5-10 psi. So you can get boiling water washing your roof, rather than an explosion.

SurferJoe46
28-07-2006, 06:05 PM
For pressure and temp over-runs, we use a T&P Valve...temp and pressure to protect the home and occupants. Nothing like having a crater where it once existed.

Actual water temps here on domestic water heaters is topped out at about 165 F. So far there are no requirements for mixers to limit the water temp to 140 or so at the taps, although I see that coming soon on new builds and repair/replacements of heaters.

Losses of economy that I mentioned for using electricity have to do with the generation from oil-fired boilers or nuclear generating stations or hydro-electric generation, the delivery to the ultimate homestead and..... .

..........all the aformentioned are scorned upon by the tree huggers...what do they think? Is the good fairy gonna drop off a bucketfull of electrons every night at their homes?

Most in the US are natural gas fired, others are propane and a smaller percentage are electric. Solar pre-heaters have not worked out well in the US...they are expensive and a service nightmare for homeowners. Maybe if they get a lot more therms captured and they get some more reliability for other than heating swimming pools with a thermal siphon.

Your harmonics trick reminds me of a guy who had placed large loops of wire in coils under a transmission line to pick up the induced electricity from eddy currents on the wires. He got away with it for years via the FCC ruling that any emissions into the ether would be fair game to anyone who could receive them.

The law changed, or he died or had his knees broken and he went away with a snivel. It is now illegal to harvest or gleen electricity via induction.

Others have placed induction coils around the meters to slow the wheel from turning the gears in normal speed. This works pretty good for people on remote radio-linked readers where the electric company doesn't have to physically read the meters but get the numbers from a transmitter when they are in range...about 30 yards or so.

personthingy
29-07-2006, 12:14 PM
I don't know why people freak out so much about the token losses of heat from a HWC. Mines installed in my bedroom, so any losses warm my room. Given most people heat thier rooms, why is it so bad that a little heat got into their lives?

Terry Porritt
29-07-2006, 12:29 PM
I don't know why people freak out so much about the token losses of heat from a HWC. Mines installed in my bedroom, so any losses warm my room. Given most people heat thier rooms, why is it so bad that a little heat got into their lives?

Fazackerly !

I had to fit a small heated towel rail in the airing cupboard after an insulating blanket was wrapped around the hot water tank :D

Now we have an even better insulated new tank, and there would be no warmth in the airing cupboard at all if it wasn't for the small heater.

On the other hand, the cupboard heater can be switched on and off as required, so all in all, a well lagged tank +extra heater is better than a poorly lagged tank.

Graham L
29-07-2006, 01:25 PM
The losses aren't token with an old cylinder "insulated" with a bit of underfelt. Since most old cylinders are too small by modern standards, the themostats are turned up, and the losses increase considerably.

The "airing cupboard" made some use of a bad situation. Better insulation is much cheaper.

Mains pressure cylinders, which allow smaller pipes, so less hot water cools in the pipes when the taps are turned off, and copper pipes which are easier to heat up than traditional cast iron water pipes, both help. (Uranium pipes would be even better than copper. :D It's got a specific heat of about 0.12 against 0.38 for copper. I suppose George W would object to that. :( )

Billy T
29-07-2006, 02:49 PM
Your harmonics trick reminds me of a guy who had placed large loops of wire in coils under a transmission line to pick up the induced electricity from eddy currents on the wires.

I think that story might just be an urban myth Joe. Firstly it is nothing to do with eddy currents, and secondly, the coupling distance would not be closer than about 5-7 metres and air-cored tranformers are very inefficient at 50/60Hz. You would certainly generate some power off the loop, but I doubt that you could get useful levels, though GF may astound us all with some calculations if/when he spots this.

With a big enough coil with plenty of turns you might get sufficient power to light a couple of small bulbs or to run your cowshed radio, but that's about it. As for getting away with it, I'm pretty sure that any substantial coupling would put a bump in the line impedance characteristics and be traceable back to within a few hundred metres or less of the perpetrator's location.

Cheers

Billy 8-{)

Edit:

Busted: Stealing power via a coil under power lines.

For this myth the MythBusters created a large coil of wire, and wrapped it around a PVC pipe box. They then hoisted it underneath powerlines in order to "catch" some electricity. They were able to obtain about eight millivolts of electricity. They determined that siphoning a practically useful amount of electricity in such a manner would require thousands of pounds of wire, and would be extremely impractical and dangerous, as well as being illegal.

tweak'e
29-07-2006, 06:12 PM
err billy...... do you remeber the farmer who the electricty company was trying to take to court some years ago because he rigged up some big coils on his cow shed roof and ran his cow shed of it. he was directly under 66kv lines afaik. not sure what was the outcome.

Billy T
29-07-2006, 07:29 PM
err billy...... do you remeber the farmer who the electricty company was trying to take to court some years ago because he rigged up some big coils on his cow shed roof and ran his cow shed of it. he was directly under 66kv lines afaik. not sure what was the outcome.
I don't recall that tweak'e, and it may be just another local urban myth as well, or he may have attempted unsuccessfully and been caught.

You are a tech so you will know about induction & magnetic coupling. A power line passing overhead represents less than a single turn, and the magnetic field strength is not high at the distance that the coupling coil must be located away from the line. In addition, a typical 66kV line does not operate at a very high current, and a multi-turn coil should operate as a step-up transformer, not a stepdown.

Personally I can't see it working, but I'm open to serious calculations that show it could.

Cheers

Billy 8-{)

tweak'e
29-07-2006, 09:09 PM
dunno on the math, i havn't done that for a looong time. i remember the story ran on the news years ago.

Terry Porritt
29-07-2006, 09:35 PM
There used to be an "urban legend" circulating back in the 50s, I think I heard it at the Slade Radio Society in Birmingham, that someone who lived fairly close to the 400KW, 200Khz, long wave BBC transmitter at Droitwich in the UK was able to draw off a sizeable amount of power from the magnetic field component by means of a large frame aerial.

The culprit was apparently detected by the station engineers noticing unusual variations in power output, or something.

That sounds much more plausible than a coil under high voltage transmission lines.

But I don't know how true it was.

SurferJoe46
30-07-2006, 03:58 AM
I was much younger and infinately more impressionable when I heard about the induced power via the coils of wire under the transmission lines....so it might've been like the lady, the wet poodle and the microwave story.....somewhat plausable, totally junk.

Damn...now you've busted the memory I had of the one and only time my father told me anything in confidence.... :xmouth: .

Graham L
30-07-2006, 03:09 PM
I don't think I'd bother with a "coil" of wire. You want an aerial which will collect radiated power in the near field. It's volt/metre which counts; a bigger (longer) aerial will pick up more energy. I would use a long wire parallel with the power line. Earth one end, and you'll certainly see some volts at the other end. But there'll never be any great current.

I don't think Billy's idea that the power loss would be detectable by impedance discontinuities would worry me. With a wavelength of 5-6000 km , and sometimes hundreds of kV on the lines, TDR test equipment isn't often used. (My rough guess at the characteristic impedance of the big lines is about 600-800 ohms, BTW, what is the diameter of those conductors -- I guessed 3"?). The impedance detection used on these lines detects arcover, (shorts) by comparing the current and voltage in each section. It's so that the protection switches can be operated. The amount of power you could couple out wouldn't even be noticed. The whole idea of the power distribution system is that current will flow to loads.

But the inspection crew in their helicopter might notice something.

RF can do funny things. Wireless World occasionally had a story about fires near naval bases in England. The big transmitters had enough output to produce sparks from metal objects. When the objects were gas stoves ...

I think the best way to get power from a 200 kHz transmitter would be with stakes driven into the ground. The earth (image) current would give quite a good voltage gradient for quite a distance past the earth mat.

I've measured 2v pk-pk (common mode) on long open wire transmission lines a few miles from Gebbies Pass. 3YA has (had?) 150 kW, I think, but that was out of the near field. I've had 50 V pk-pk on 75 ohm receiver inputs with horizontally polarized arrays, a few hundred metres from a 100 kW pulse transmitter.

godfather
30-07-2006, 06:31 PM
The capture of some "useable power" from induction under transmission lines is real. But not practical.

Not sure if it's still in use (photovoltaic may have rendered it obsolete) but north of Hanmer Springs there was a remote radio repeater (belonging to the old NZED) that was powered by a lengthy aerial conductor under the ISL-KIK (Islington to Kikawa) 220 kV line. As they also owned the line it was legal.

But the problem was regulation of the small induced power level, as it was totally dependent on the ISL-KIK circuit load current. You would only get a few watts, getting close enough to get anything useful is a tad difficult at 220kV. Really only useful for a battery charger or similar.

But there would be no way to detect it, as it would simply show up as inductive losses. They would be incalculable as a proportion and I doubt that the "differential protection" circuits would even know they were there.

Billy T
30-07-2006, 11:08 PM
I don't think I'd bother with a "coil" of wire. You want an aerial which will collect radiated power in the near field. It's volt/metre which counts; a bigger (longer) aerial will pick up more energy.
I agree with the antenna theory for voltage capture, but that is of no practical value for gathering usable energy levels at 50Hz. You need close inductive coupling for that, in order to transfer enough energy to produce actual power.

I do think that any system capable of drawing usable power would be potentially detectable via line tests, I have seen some amazing technology in recent years that can locate impedance variations over long distances, and they would not be doing their search at low frequency. It possibly might not work on power lines, but I see no insurmountable technical barriers.


I've measured 2v pk-pk (common mode) on long open wire transmission lines a few miles from Gebbies Pass. 3YA has (had?) 150 kW, I think, but that was out of the near field. I've had 50 V pk-pk on 75 ohm receiver inputs with horizontally polarized arrays, a few hundred metres from a 100 kW pulse transmitter.
Hmmm....That's about 30 watts of RF energy, or nearly 700mA in the receiver input. I'd expect smoke at those levels unless the pulses were of very short duration, in which case the mean energy level would be pretty much useless.

I still don't think that any useful power is likely to be realised. Bear in mind I'm not saying that it is impossible to couple energy from a high tension powerline, I am simply saying that the amount of energy obtained is not worth the effort.

Under the right conditions you can get free fluorescent lighting though, that is quite easy to achieve from both powerlines and high power RF sources. I used to use a 4 ft fluorescent to check for power radiation from 25 watt marine transmitters running on a base loaded whip in my workshop.

Cheers

Billy 8-{)

Graham L
31-07-2006, 05:04 PM
I read somewhere (in Scientific American?) about a method of getting power from the extrahigh voltage distribution lines. Electrostatic motors. :D

Billy, I wish you would read what I write. :(

I mentioned "voltage", not current or "usable power". A coil as described would be useless for anything, hardly even for detection, as was said. . I didn't suggest running a water cylinder from the long wire. As far as I know, the only impedance test on the grid is the continuous monitoring for protection, and that's just looking for high current/low voltage. The amount of corona on a long line would exceed the amount of energy pulled by anyone with a long parallel line. Wet weather would make a big difference., too.

It was a pulse transmitter, as I said; 20 microsecond pulses, at quite low PRF. Not useful energy, but it was enough to take out the front ends , until I put some diodes across them. Curiously FET inputs could take it; it was the transistors in an IC which were fragile.

Running a fluorescent tube from a 25W transmitter isn't "free" energy. You'd find it cheaper to plug it into the 3 pin socket.

Some of the NZ stories on this theme mention dairy sheds lit by the captured energy. I suppose electric fences is the obvious application. :D

Billy T
31-07-2006, 06:34 PM
Billy, I wish you would read what I write. :(
Yeah, I did read what you wrote Graham, but the point at issue was "usable power levels" not merely detectable voltages, so while I liked your technical experiences, they didn't add a whole lot to the discussion, hence my comments on relevance.


Running a fluorescent tube from a 25W transmitter isn't "free" energy. You'd find it cheaper to plug it into the 3 pin socket.
Gee, I wish you would read what I write Graham. :p

I didn't use the fluorescent for illumination, and I don't recall claiming it to be free energy either, I used it to verify that radiated power existed. We lacked a suitable 25W dummy load or power meter you see, so a short press of the mic key lit up the fluorescent and gave a quick indication of RF out.

Cheers

Billy 8-{) :D

Terry Porritt
31-07-2006, 07:01 PM
OK, all that notwithstanding, here are some real figures :)

I dug out an old frame aerial that I used to use for medium wave DXing before all the available 'broadcast' wavelengths were sold off for Maori radio and other junk local radio etc.

Octagonal shape, 650mm nominal 'diameter', Q~200.

At 26Km from the Titahi Bay 567Khz medium wave transmitter, with the aerial tuned to resonance, I can get 175mv into a 10Mohm, 22pf probe connected to an HP 400E voltmeter.

It is left as an exercise for anyone to work out what sort of power could be obtained within say 500 metres of the masts. :)

Graham L
01-08-2006, 03:19 PM
... Under the right conditions you can get free fluorescent lighting though, that is quite easy to achieve from both powerlines and high power RF sources.

"free fluorescent lighting" does not mean free or illumination?

But you didn't give us the benefit of your experiences getting it from the powerlines. I believe they frown on bypassing the meter. :D

In case you have never noticed, this section of the forum is not always relevant to anything Billy.

[quote=Billy T] ... I do think that any system capable of drawing usable power would be potentially detectable via line tests, I have seen some amazing technology in recent years that can locate impedance variations over long distances, and they would not be doing their search at low frequency. It possibly might not work on power lines, but I see no insurmountable technical barriers.[/b]

Any system capable of drawing usable power is usually detectable by a visual inspection. The distribution system isn't ever going to be shut down to look for such things. I can assure you that impedance measurements on the high voltage distribution lines would be fairly meaningless. They are so long that there would be rain at some part, and the capacitance (and thus impedance) change that causes is quite severe. That would also seriously affect any TDR measurements. (That's quite apart from the fact that you wouldn't get me doing those measurements on lines at a few hundred kV.)

Anyway, the power system doesn't use the maximum power theorem, and matched lines, so I have strong doubts that the impedance is ever measured, except by the ratio of volts and amps, which is a "system" rather than "line" thing, because it depends on the load. A flashover fault will cause a sudden change in it, which will normally cause urgent switching operations to isolate the fault, rather than searches for freeloaders. The source impedance of the generation end is as close to zero as they can get it. The real part of the transmission system impedance is as low as they can economically get it, and there is a fair amount of money spent on capacitors and inductances to correct the imaginary part.

Terry, you wouldn't get within 500 metres of the tower. That's why they have the big fences. I remember being told years ago that you have to walk with care near the base of the tower. The voltage gradient across the ground can cause quite interesting effects if you take long paces. Two stakes in the ground and a big diode would give you some useful power. :D

Graham L
01-08-2006, 03:42 PM
P.S. Terry:
Again, I think a long wire would be better for extracting energy at 567 kHz than a loop. Field strength is measured in volts/metre, so if you want more volts, you need more metres. A tuned circuit can only use what it's got; if the tuning improves the volts, you are raising the impedance which is supplying those increased volts (or millivolts). You used that frame's directionality to improve your signal to noise+signal ratio, when more signal+noise can actually be a handicap.

Billy T
01-08-2006, 05:12 PM
"free fluorescent lighting" does not mean free or illumination? But you didn't give us the benefit of your experiences getting it from the powerlines. I believe they frown on bypassing the meter. :D
Sorry Graham, I should have explained.

Firstly, in that context "free" simply meant it wasn't a source that you should really be paying for.

Secondly, the light output was not adequate for what one might usually call "lighting-grade illumination" but it was bright enough to show the presence of RF under daylight conditions

As for getting free lighting from powerlines, the voltage field below a 110kV or 220kV line is often sufficient to strike a flourescent tube and produce a reasonable amount of light output. Holding one end of the tube in your hand and waving it about will usually provide a pretty fair Star Wars light-sabre imitation at night.

For more light, put a short metallic extension 20-30cm onto the free end (connecting to the filament pins), and wire the end you hold so that you make an electrical connection between your hand and those filament pins as well. Bare feet completes the "illumination enhancement" program.

It is quite harmless and reasonably painless unless you are particularly sensitive to very weak electric shocks. I can think of several ways to get similar (weak) illumination inside a building situated below the lines.

The voltage field below HV lines ranges from 2 kV/m up to 5 kV/m, and may be significantly higher if you are on rising ground under the mid-point of the lines between pylons (maximum droop) and getting within 3-4 metres of the minimum safe distance. You need about 2.5kV/m to get the tube to illuminate, though some may work at lower voltages.

Cheers

Billy 8-{)

Graham L
04-08-2006, 04:40 PM
Billy: I knew all that. I thought you might have found some better way.

Terry:

There's a lot of grunt close up. But you need quite a lot to catch it.

The CCIR graph says that a 1kW transmitter will have a field of 110 dBu at 1 km. That's approximately 300 mV/m. 2YA has 54dBW -- 250 kW, giving 4.74 V/m at 1 km. (The CCIR figure is for a "short monopole 1/8 wavelength, whereas the Titahi Bay tower is 220 m, closer to half a wavelength, so the numbers should be bigger).

A half wave dipole in that field would produce close to 800 volts at the centre. If you match the load, you'll get about 2.2 kW in it. But the halfwave dipole needs to be vertical. And it would pay to raise the bottem end well above the earth. Someone might notice this thing. The wavelength is 529 m.

The energy density is about 0.6 W/m^2 . A 10 m high whip might collect 60 watts.

At 26 km, over salt water, the fields should be about 30 dB lower. That's still a strong signal.

Terry Porritt
04-08-2006, 05:10 PM
Perhaps some enterprising soul could construct a boat to cross Cook Straight from Titahi Bay, powered by 2YA? :rolleyes:

Graham L
04-08-2006, 05:20 PM
There is another 250 kW RNZ transmitter (on 657) kHz , plus a 48dBW one on 783 at Titahi Bay, so you should be able to get nearly three times the power. But it's inverse square ... before long you would be rowing. (Or swimming anyway, the wind would topple you)

Kelem
04-08-2006, 05:22 PM
Lance,
HWC's are expensive to run period. Short showers, maybe share baths? if you are using a whole heap more power for some reason, maybe the TS is US (easy to check)
If you aren't confident get a sparky, also loose connections can be a problem.
If you really want to save money solar will pay for its self, depending on usage rather quickly. Or on demand gas system is pretty good and may be able to hook up the hob for more savings if you haven't already - they use a bit of power as well.

Cheers Kelem