Hoping one or more of the tech heads lurking here can give us an answer on this product
Earthwise power saver - scam or what?
(68 posts) (18 voices)-
franks
MemberIts a scam, comments elsewhere makes interesting points
http://forums.whirlpool.net.au/forum-replies.cfm?t=1631059Posted Wednesday 2 Feb 2011 @ 12:31:54 am from IP # -
swanning_it
MemberThere is another device on the market which apparently "aligns" electrons by "super conductivity theory" (don't ask me how) and saves about 10%, but was quite expensive from memory.
Posted Wednesday 2 Feb 2011 @ 1:37:42 am from IP # -
ghostgum
MemberAnother good one in the past was the specially treated copper that allowed electrons to flow in one direction easier, resulting in less loss in power cords. The copper had to be used in the correct direction with the active and neutral wires. The "how it works" for this product omitted to explain that mains power is AC, and it changes direction every 10ms.
Back in the days of coax 10Mbps Ethernet cabling, someone demonstrated power line communications getting 10Mbps, much better than other power line methods of the day. Unknown to most viewers, the power cords had a coax cable inside, which connected through the power board and then to the other computer.
Posted Wednesday 2 Feb 2011 @ 1:49:31 am from IP # -
I'm a bit worried that none of the comments on the Whirlpool forum come from anyone who knows much about this stuff, hence I'm turning back to the ATA. As an ATA member I'd appreciate an informed view. Is anyone able to comment, or is this the right forum to ask?
The product in question is still advertising in the Wollongong newspapers which is where I came across this. If it is a scam, we probably have an obligation to take this to the ACCC.
I see a similar product is also advertised and these are popping up around the place.
Posted Friday 18 Mar 2011 @ 3:07:18 am from IP # -
ghostgum
MemberAt least one of the Whirlpool comments looks reasonable:
http://forums.whirlpool.net.au/forum-replies.cfm?t=1631059#r19Posted Friday 18 Mar 2011 @ 3:25:04 am from IP # -
Jeffbloggs
MemberDeepfried
I once had a look at this device on another thread. The functionality seems legit as a power factor "control" device, however, in my opinion it will only work on old rotary dial style meters, that generally do not have PF correction electronics. Therefore there use is limited. Also the type of load connected will effect it's performance, inductive/capacitive loads will benefit more than resistive loads etc. Chk out this link for more on how this works:
http://en.wikipedia.org/wiki/Power_factor#Power_factor_correction_in_non-linear_loadsBTW some of the more expensive florescent lights have PF correction built in, this type of load will not be helped by installing another PF correction device.
I hope that satisfies your curiosity. If not feel free to ask any questions here, I will try to respond.Ghostgum
I agree with DanD analysis, but only on the basis that he is referring to a modern PF corrected electronic meter, a analog rotary dial type meter functions as an inductive load on the circuit, and as such is effected by the type of consumer load connected.
http://en.wikipedia.org/wiki/Electricity_meter#Electromechanical_metersPosted Friday 18 Mar 2011 @ 3:33:08 am from IP # -
Jeffbloggs
MemberDeepfried why do you say that after reading my post?
Posted Friday 18 Mar 2011 @ 3:45:06 am from IP # -
ghostgum
MemberEven the rotating disc energy meters spin at a rate proportional to real power. That wikipedia article states "the effect is such that a force is exerted on the disc in proportion to the product of the instantaneous current and voltage."
Posted Friday 18 Mar 2011 @ 4:07:50 am from IP # -
Jeffbloggs
Memberghostgum
Thats why they are not PF corrected. PF is the "phase shift" between current and voltage, if their individual curves are at different points at different times (ie they do not peak at the same time at a PF of 1 the disc will not react accurately, but as stated before this depends on the consumer load behind the meter for any PF correction device to work effectively. (for example: when these curves are offset, how does the the voltage/current lag/advance effect the "proportional" spinning of the disc, if the volts and amps "drive" the disc at different times?) Hence the device will only work with certain loads and with a analog disc type meter. Unless you make it a capacitive or inductive load (so not a resistive load PF 1) the effect of the device will be zero. An electronic meter measures both values of V&A independently from each other, and as such is mostly unaffected in it's calculation of kWh.Posted Friday 18 Mar 2011 @ 4:45:22 am from IP # -
ghostgum
MemberJeffblogs, real power is calculated using the instantaneous product of voltage and current. This gives you the in-phase component of phase shifted voltage and current, but it also works for non-sinusoidal waveforms.
An analogue power meter is like a PMMC meter, but with the magnet replaced by a current coil. The force on the voltage coil (against the spring), is proportional to the instantaneous product of the voltage and current. The rotating disc energy meter uses this same method to measure real energy.
This is first or second year electrical engineering.
Feel free to correct the remaining errors in your posting
Posted Friday 18 Mar 2011 @ 5:30:36 am from IP # -
Jeffbloggs
MemberGhostgum
Don't get me wrong, I was not stating that the device worked "economically", in fact I was trying to point out that it wouldn't work at all on a electronic type meter, and only to a small degree on a analog meter, especially so if you did not have PF compensated loads.Regardless of that, on the point of analog disc meters, how are they PF corrected? How does it compensate between PF phase shift and voltage and current value fluctuations? The network is never a consistent voltage, even if it does say 240V on the plug
If they are not PF corrected, please explain how they measure (read spin) at actual power consumption rates? For example: If real power is measured at PF of 1 ie voltage of 1V and current at 1A = 1W, then how does the analog meter respond to a 1V at 1A at PF of 0.5? Will it spin faster/slower or at the same speed?BTW PF correction is "paid" for in WA. Please see Power Factor section for WA mandated pricing: http://www.austlii.edu.au/au/legis/wa/repealed_reg/eopcb1996618/sch1.html
Posted Friday 18 Mar 2011 @ 6:20:58 am from IP # -
ghostgum
MemberJeffblogs, I am saying that it won't work on a digital electricity meter and it won't work on an analogue meter, because both measure real power, and so are unaffected by power factor correction. You can make a meter that responds to apparent power, but that isn't the sort installed in residential properties.
Real power is the instantaneous product of current and voltage. Real power meters respond to this product by virtue of the magnetic field generated by the current coil acting against a magnetic field generated by the voltage coil, and the mechanics of an analogue meter filters out the 100Hz waveform to give you the average over a number of cycles. In a real power meter, this instantaneous product of current and voltage produces a force on the needle, which is countered by the spring. Since an ideal spring deflects linearly with force, the needle deflection is proportional to the force and the real power. For a rotating disc energy meter, the force pushes the disc around, which is resisted by a permanent magnet on the other side of the disc, such that the speed is proportional to power. [If you reduce the magnetic field of the permanent magnet, then the disc has less resistance and spins faster - you don't want to do that!]
This measurement of real power works when the voltage and current are DC, it works when they are AC sinusoid, it works when they are square waves, in fact it works on any waveform shape. Just don't expect to measure 1MHz currents on a power meter intended for 50Hz. One thing you should learn in an electrical engineering course is how to measure things, selection of the most suitable meter, and how to avoid measuring the wrong thing.
1V 1A PF0.5 spins at half the speed of 1V 1A PF1, since PF is defined as real power divided apparent power.
PF correction is not usually done on residential properties, I presume because the power factor isn't usually that bad. A factory building with the ceiling covered in fluorescent lights with iron ballasts (and no PF correction capacitors) and induction motors on the factory floor (again with no PF correction) would draw more current than necessary, and hence increase losses in the distribution network, and require larger sized distribution transformers than necessary. This is why the distribution company puts a financial incentive on the power user to fix it.
In my house, the average power factor is about 0.9, based on the difference between the distributor's energy meter and my current clamp meter.
Posted Friday 18 Mar 2011 @ 9:26:08 am from IP # -
ghostgum
MemberI should add that the way you measure power factor is:
1. Measure real power (average of instantaneous product of voltage and current).
2. Measure apparent power (product of RMS average voltage and RMS average current).
3. PF = real power / apparent power.You do not measure power factor by working out the phase shift between the current and voltage, and then taking the cosine. The latter would work for pure sinusoidal waveforms, but gives an inaccurate result if there are any harmonics. I have a suspicion that some cheap plug in power meters unfortunately use this method.
Posted Friday 18 Mar 2011 @ 9:50:13 am from IP # -
Jeffbloggs
MemberGhostgum
I am not trying to be argumentative, but can I ask the following about an inductive dial type meters and how they function? I have no problem with zero benefit when PF correction is used with digital type meters, neither with your PF etc. methodology. Rather I am still not convinced of the non-effect of PF on analog induction meters with a "watt-meter motor".On a single phase inductive meter, if the voltage coil is 90 degrees (BTW at 0 degrees it measures kvar) to the current coil, with drag magnets that retard the disc, will a difference in PF cause a difference in the force applied (normally acting at the same time at unity) to rotate the disc through eddy currents, through the delay between the current or voltage coil "acceleration"? If not why? How do the forces of either current or voltage coils interact with each other if they are "PF out of phase"? Given your PF statement of 0.5 runs at half speed, why does this not apply to the analog meter disc with a phase variance between the potential and current coils?
Posted Friday 18 Mar 2011 @ 12:12:02 pm from IP # -
ghostgum
MemberYes, sun2stream, it's snake oil.
Jeffblogs, I can't find a good description of the coil arrangement in the electromechanical induction watt-hour meter, at least not one good enough to visualise the fields and currents acting on the aluminium disc. Yes, a difference in PF does cause a difference in the force applied. It's got something to do with one of the coils causing an eddy current in the disc, which acts against the field produced by the other coil. This depends on the phase relationship between the two fields.
Posted Friday 18 Mar 2011 @ 10:15:46 pm from IP # -
Jeffbloggs
MemberGhostgum
So in conclusion would it be safe to say that for digital type meters the effect of a PF correction device is like snake oil, it has none whatsoever, however, physically the analog watt-meter motor disc type meter is affected by a PF correction device, but economically it is unlikely to make the claimed +25% reduction difference in household load or in a metered kWh reduction.
In either case, it is unlikely to actually reduce actual consumption of power, but rather it can affect "how" the power is metered in analog watt-meter motor meter. It will only have this type of "positive" effect depending on the household load type.
In fact for it to be economically beneficial for the householder, ie make the meter run slower, it would need to purposely distort the PF from unity, which in turn would/could reduce the efficiency of the network, therefore actually creating a possible energy loss in the network. Any claim of it "saving" actual energy would be unlikely, however, it might effect the individual performance of a load, by "optimizing" it to a watt-meter motor metering device.
Some PF correction devices claim to also include power conditioning, to filter out power fluctuations and distortions, and sometimes also serve as a "protection" device. This functionality would have to be investigated on its own merit.
S2S
Why voluntarily read the posts and then criticize their content without contributing to the discussion? Snake oil? I thought I was the "resident metaphysical scientist". I was really getting used to that role too, after you proposed it!! lolIf you know how it does/doesn't work then please explain it to us uneducated souls so that we too can put it to bed. The whole purpose of this forum is to gain perspective and exchange information, it was not my question, but I did at least try to respond to the best of my knowledge, and by doing so it would seem that my original statements were vindicated. That is at least so far...
Posted Saturday 19 Mar 2011 @ 2:55:24 am from IP # -
Andy Chee
MemberEfficiencies gained on the utility side of the meter, will not be reflected by a change in meter readings on the household side of the meter. This applies to all meters.
Basically if you have very low PF, the utility will have to generate say 1.4kW to get you 1kW. Your meter will read 1kW and they'll bill you for 1kW. They WILL NOT bill you for 1.4kW.
Posted Saturday 19 Mar 2011 @ 3:24:23 am from IP # -
Jeffbloggs
MemberAndy
I agree, but that doesn't exclude a PF "correction" device from manipulating an analog meter kWh reading. The PF device should really be called a PF "distortion" device, to make the most use of your statement.Posted Saturday 19 Mar 2011 @ 3:52:00 am from IP # -
Andy Chee
MemberA solar grid connect inverter generating excess electricity will turn an analog meter backwards.
Might have to try this, but I think a solar grid connect inverter generating excess electricity will stop an ordinary smart meter (ie. NOT co-gen) from counting forwards, but it will not count backwards like the analog meter.
As for a "device" to manipulate analog meters (with the exception of the GCI example above), I highly doubt it. But I can easily test it if you know of a device.
Posted Saturday 19 Mar 2011 @ 4:22:35 am from IP # -
Jeffbloggs
MemberAndy
Possibly a bit off topic, but I was thinking that maybe, if you wanted to be very cheeky, a 3-phase analog meter could possibly be modulated by manipulating the flow of input over one phase to feed into the output of another phase. You would need a phase shift device I suppose, to bring the two in sync, and vary both PFs in the process so that you could extract a difference. I'm not quite sure if it would work on a differential 2phase type 3phase meter, or if at all. I know these type of phase converters are available and sold for converting single phase power into 3phase power for rural properties with only one line connections. But don't come whining to me if you blow yourself up or get caught doing it! This is not a safe procedure and it comes with no recommendation from myself, I am only interested in the theoretical possibility of this working, nothing more.BTW do you work in a lab or something?
Posted Saturday 19 Mar 2011 @ 5:20:50 am from IP # -
ghostgum
MemberJeffblogs, you wrote "So in conclusion would it be safe to say that for digital type meters the effect of a PF correction device is like snake oil, it has none whatsoever, however, physically the analog watt-meter motor disc type meter is affected by a PF correction device,"
No, that is not the conclusion. The analogue watt-hour meter is unaffected by PF correction device [assuming that we aren't talking about a 0.1PF load!]
I found one diagram of the coil arrangement of the electro-mechanical watt-hour meter:
http://books.google.com.au/books?id=W2MqvVZ6JFQC&lpg=PA1404&ots=c8uYfWSXlw&dq=electromechanical%20watt-hour%20meter%20coil%2090%20degree&pg=PA1405#v=onepage&q&f=false
If that link doesn't work, then do a search for "How It Works: Science and Technology
By Marshall Cavendish Corporation"The diagram shows that the voltage coil produces a magnetic field parallel to the disc, and the current coil produce a field perpendicular to the disc. The voltage coil thus produces an eddy current at 90 degrees to the field of the current coil, producing a force to turn the disc. The force is proportional to the instantaneous value of the magnetic field, which is proportional to the current in the coil, and so the result is a force proportional to the real power.
In summary, any "power saver" device based on power factor correction isn't going to work on either analogue or digital domestic watt-hour meters.
Posted Saturday 19 Mar 2011 @ 11:39:43 am from IP # -
ghostgum
MemberAndy Chee wote "Might have to try this, but I think a solar grid connect inverter generating excess electricity will stop an ordinary smart meter (ie. NOT co-gen) from counting forwards, but it will not count backwards like the analog meter."
There are a variety of meters, and some do undesirable things when you export power.
The old electro-mechanical meters will spin backwards. This can be interesting if you make it spin past zero, and then get a very large energy bill. Hopefull some sanity checking of numbers at the distributor will avoid this.
Some digital meters will simply not count when you export power. I had one of these. It advanced overnight, then the reading was stationary during daylight hours as the solar system exported.
Some digital meters will count forwards when you export. That is, your exports are recorded as energy consumption. You don't want to turn on your grid solar system if you have one of these.
Some digital meters are true 4 quadrant meters. These can measure imports separately from exports, and can also measure power factor. AMI smart meters are in this category.
Posted Saturday 19 Mar 2011 @ 11:46:31 am from IP # -
Jeffbloggs
Memberghostgum
You confuse me!
Why did you say: "Yes, a difference in PF does cause a difference in the force applied. It's got something to do with one of the coils causing an eddy current in the disc, which acts against the field produced by the other coil. This depends on the phase relationship between the two fields." and now you renounce that claim? Or what was your intention with that statement?Are you claiming it does not effect a watt-meter motor meter (WMMM) at all, or just not substantially, ie 25% or more reduction?
Is it true that at zero voltage the potential coil will not exert a force on the disc (ie it will not spin), likewise at zero current the current coil will not exert a force on the disc. Why then doesn't PF play a role in the amount of force exerted on the disc at any point in time when these two are offset? ie the speed at which the disc records kWh, because the voltage force and the current force are out of sync? If one happens after the other the disc will not spin, at what PF difference does this effect smooth out to provide a continuous force to drive the disc? For example a simple fish tank pump can have a PF around the 0.25. How will this type of load affect the kWh reading of the WMMM, if not why?
In that link you posted it says:
"The turning force, or torque, acting on the rotor disc is proportional to the product of the voltage and the current and the power factor of the load being metered". So when you change the PF isn't the rotor disc force and resulting disc speed affected, and therefore the measurement of kWh?
What am I not getting here, could you please explain how you think it works, as the principles seem to be as clear as mud...
BTW thanks for enduring the discussion so far.
Posted Saturday 19 Mar 2011 @ 4:11:45 pm from IP # -
swanning_it
MemberNot sure if this has been said, but going right back to school, we were always taught a wattmeter is just that. It measures true power only (W). It measures neither apparent power (VA) nor reactive power (VAr), so power factor correction has no effect on a wattmeter.
Posted Saturday 19 Mar 2011 @ 9:09:33 pm from IP # -
swanning_it
MemberIn thinking about my last comment above, I think I may wish to retract it with my thoughts being that even though a wattmeter doesn't read VAs or VArs, by altering the power factor of a load (to closer to unity) without varying the load, then W and VA become closer which means W has to increase (which is why supply authorities want PF correction). So in effect this device (if based on just PF correction) may change a household power bill, but it would make it higher if they are altering to a higher PF.
It would lower if altering the PF to a lower value, which I'm sort of guessing would be almost regarded as power theft.
Posted Saturday 19 Mar 2011 @ 9:28:14 pm from IP # -
ghostgum
Memberswanning_it, altering the power factor without altering the load (which determines the real power), causes the VA to become close to W. It doesn't cause the real power (W) to change. What it does do is reduce the supply current, and hence it reduces distribution losses, the size of needed substation or pole transformers, and the requirement for PF correction in the network.
The power consumed from the network doesn't vary when the customer adds PF correction.
It's this sort of confusion that allows theses scammers to market this "power saver" devices.
Posted Saturday 19 Mar 2011 @ 9:51:18 pm from IP #
