Author Topic: Dirty Electricity  (Read 10276 times)
Ash
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Re: Dirty Electricity « Reply #15 on: September 24, 2016, 04:12:37 PM » Author: Ash
Compared to the power of the devices you have to correct for, the little pesky plug will have no effect anyway. Its capacity is smaller than the steps (i.e. size of one capacitor in the bank) at which the proper PFC system works...
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wattMaster
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Re: Dirty Electricity « Reply #16 on: September 24, 2016, 04:14:05 PM » Author: wattMaster
It's odd that some people will do so much to save a little energy, even if it actually increases power usage.
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Ash
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Re: Dirty Electricity « Reply #17 on: September 24, 2016, 05:00:05 PM » Author: Ash
Green is not limited by sense, is it ? Havent you seen enough proof for it in the lighting field allready ?
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wattMaster
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Re: Dirty Electricity « Reply #18 on: September 24, 2016, 05:01:10 PM » Author: wattMaster
Green is not limited by sense, is it ? Havent you seen enough proof for it in the lighting field allready ?
LED is the best example of this.
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marcopete87
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Re: Dirty Electricity « Reply #19 on: September 28, 2016, 11:08:51 AM » Author: marcopete87
But then why don't people take action against them? ???
like against
- water purifier
- pseudo medicine (Homeopathy is the biggest scam)
- complottism

hey, if someone act against them to protect himself, it is associated with [pick an famous related company name] lobby!
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hannahs lights
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Re: Dirty Electricity « Reply #20 on: September 28, 2016, 01:15:20 PM » Author: hannahs lights
Dont forget that domestic electric meters measure real watts only and not reactive power so if you have a load that draws say 50 real watts but also say 30 reactive watts you only get billed for the 50 watts so trying to add capacitors for power factor correction won't do you any good at all. Another scam that we saw in the UK was a device that reduced your voltage to 220 from the nominal 240/250 we usually get the claim was that it reduced consumption of household appliances complete rubbish of course anything with an SMPSU would draw more amps to try to compensate fore the reduced voltage it was outed as a scam and these devices soon disapeared
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Ash
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Re: Dirty Electricity « Reply #21 on: September 29, 2016, 02:09:26 PM » Author: Ash
PFC does matter, not in homes but in bigger systems like an office or the like, where the meter still does not measure reactive power. For simple reason : How many computers / lights / ... you can connect to one 16A circuit, when they are HPF vs low PF. And therefore how many circuits (so wiring materials, breakers, and size of main electrical service connection) you need for the place. Those things cost and they may cost more than the difference in HPF/LPF Fluorescent gear for example



The 220V thing - Its effect would vary based on the load connected :

For switching power supply devices :
Its what you describe. But such devices are generally small part of the energy used at home, so dont really matter compared to the other stuff

For heaters :
The heater will work at 220^2/240^2 = 0.84x of its full power, so indeed take less power... but most appliances with heater also have a thermostat that clicks it off when the something to be heated reaches the correct temperature

If we disregard thermal losses, the temperature at which the thermostat clicks off depends only on the amount of heat (Energy) put into the substance. So the thermostat will click off after exactly the same energy used, so nothing is changed at all

If we account the losses, as Fourier's law says Q is proportional to the temperature difference between the heated thing and the ambient. The energy lost is proportional to Q * time. For appliance that is switched on to get to the needed temperature once - like kettle, the slower heating means longer time of the temperature ramp up, so more losses. For appliance that is switched on to keep temperature - like space heater, the final temperature (around which the thermostat is clicking on and off) is what matters and not the initial ramp up, the final temperature is independant on the voltage, so the losses are unchanged either

For motors :
Generally they will work "weaker" and use less power. Maybe we will not notice, so there is some energy saved. Maybe it is a compressor, so controlled by thermostat, so all the heater considerations apply. And in additions, motors generally dont like to be undervolted - They lose efficiency and if they were allready marginal or overloaded, they can stall and that means non working appliance and possibly burned up motor



There is the correct way to do things. Assume that the appliances you have are allready designed to work efficiently. If any of them uses too much power, why dont you set the thermostat lower ?

The "magic devices" maybe are doing something (220V) but they dont really solve any problem (energy saving), so are senseless to use. Except in few rare cases, one i can think of is the "button resistor" for GLS lamp installed in some hard to reach place, and that is if you cant get the proper long life lamp which would be a better choice
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Medved
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Re: Dirty Electricity « Reply #22 on: September 30, 2016, 03:09:35 AM » Author: Medved
...where the meter still does not measure reactive power.

For reactive power measuremet you always need a separate meter. So then you have one meter for the real power only and then the second, separated one for the reactive power.
Of course, both features may be combined into one meter box, these values are always displayed and billed separately.
So if there is just one meter with a single value (per tariff, if that is switched over the day), it is always only the real power.
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Ash
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Re: Dirty Electricity « Reply #23 on: September 30, 2016, 09:17:59 AM » Author: Ash
I would expect that digital (so the "smart" types) do the metering like :

Current samples I[n]

Voltage samples V[n]



And from the same sets of samples find out everything else :

Real energy = sum ( I[n]V[n] , n = SINCE EVER .. NOW )

Real power = sum ( I[n]V[n] , n = NOW-M .. NOW ) / M

Apparent power = sum ( I[n] , n = NOW-M .. NOW ) * sum ( V[n] , n = NOW-M .. NOW ) / M

Reactive power = calculate from Apparent and Real power

where M is some number of samples, like the number of samples over 20 msec or the like
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Medved
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Re: Dirty Electricity « Reply #24 on: September 30, 2016, 03:53:48 PM » Author: Medved
I would expect that digital (so the "smart" types) do the metering like :
Current samples I[n]
Voltage samples V[n]
And from the same sets of samples find out everything else :
Real energy = sum ( I[n]V[n] , n = SINCE EVER .. NOW )
Real power = sum ( I[n]V[n] , n = NOW-M .. NOW ) / M
Apparent power = sum ( I[n] , n = NOW-M .. NOW ) * sum ( V[n] , n = NOW-M .. NOW ) / M
Reactive power = calculate from Apparent and Real power
where M is some number of samples, like the number of samples over 20 msec or the like

They can do, but usually the calculation is hard coded into the basic metering chip (the summing is part of the decimation filter required to get the required dynamic range) and they are reporting just the energy and I^2 and V^2 integrals since the last readout. This allows calculation of the overall real energy consumption, but only raw indication of the apparent power and so power factor. The thing is, except the overall real energy integration, the result accuracy is very rough, so using that for calculations like reactive power or so will yield completely misleading figures, so it is unusable for that.
Many times, to save power (the internal supply uses to be extremely inefficient, mainly because the reliability and robustness against tampering are the main things driving the design), the readout periods are designed as quite long (minimize the microcontroller activity, as that consumes about 10x more power than the metering chip itself).
Of course, there are other front end chips (or their operation modes), usually feeding rather raw measurement data to the microcontroller, where any custom calculation could be made. The main problem is, that way requires way higher computing power on the microcontroller (usually some ARM or so) and that means its way higher power demand. Therefore it is used only for the industrial meters, where the extra processing is required.
The domestic meters use just the simple, slow clocked low power 8-bit cores, which are barely able to just read out, correct for callibration and then sum up just a single value (so the real power), serve the display and if really "hard loaded", feature two energy registers for two tariffs and serve the communication. So for that they have to rely on just what signal processing is implemented in the HW of the metering chip, they can not do anything else with the measured data.
So even when "smart", the meters are usually not able to do more than just the overall energy readout. Even the "actual power" display is frequently out of the computing power limits...
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Ash
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Re: Dirty Electricity « Reply #25 on: September 30, 2016, 04:03:15 PM » Author: Ash
What sort of robustness against tampering consideration affects the design of the power supply ?
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Medved
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Re: Dirty Electricity « Reply #26 on: September 30, 2016, 04:40:34 PM » Author: Medved
What sort of robustness against tampering consideration affects the design of the power supply ?

A permanent magnet, saturating the transformer core, causing the power supply to collapse, so the meter stops measuring and so recording the consumption.
So the power supply can not use any magnetic material.
Because the meter is very exposed to the overvoltage spikes (practically no overvoltage suppression from the distribution feed), the capacitive dropper is out of the game.
So what remains is a resistive dropper and maximum an "air core" coil/transformer for the power supply. Both mean very low efficiency.
And because of the reliability and simplicity, the resistor is preferred, when the related dissipation remains below about 1W or so. That means no more than 2..4mA for the complete meter circuit (as it has to work even in adverse voltage conditions). And that really does not allow anything more than just the front end chip and low frequency clocked microcontroller, the radio transmissions (20..100mA bursts) are then handled from a storage capacitor charge, so require quite some idle time for recharge.
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wattMaster
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Re: Dirty Electricity « Reply #27 on: September 30, 2016, 05:00:23 PM » Author: wattMaster
I have been thinking of high PF ballasts for bucket lights for lighting up a big dirt road. With 2 amp ballasts, I could fit 10 of them on a 20 amp circuit.
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Ash
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Re: Dirty Electricity « Reply #28 on: September 30, 2016, 05:06:00 PM » Author: Ash
Why not transofrmer (whether 50Hz or in switching PS) with some massive shielding to conduct any Magnetic fields around it and out of the way ?

Won't a permanent magnet saturate the core of the current transformer so prevent making the measurement anyway ? (or will it appear as high current, so cause the meter to record it as max power consumption ?)



You can fit 10 of them on 20A circuit, but that is bad practice. Load circuits to about 3/4's .. 4/5's of their capacity, so 7..8 buckets max. As you said, this would concern more a utility company with 10's of lanterns on the same line, not the home user. But for an office with lots of Fluorescents, this may well interest them
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Re: Dirty Electricity « Reply #29 on: September 30, 2016, 05:10:51 PM » Author: wattMaster
You can fit 10 of them on 20A circuit, but that is bad practice. Load circuits to about 3/4's .. 4/5's of their capacity, so 7..8 buckets max.
Another option is to use 2 circuits, so you could fit 16 bucket lights.
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