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Fix the voltage campaign (Australia)
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tom66:

--- Quote from: james_s on December 28, 2020, 06:45:19 pm ---
--- Quote from: nctnico on December 28, 2020, 05:21:42 pm ---Unless you use incandescent light bulbs the voltage doesn't matter at all nowadays. A switch mode PSU (which is also inside CFL and LED lamps) is a constant energy pump. OTOH higher voltages reduce current and thus losses in the power distribution grid.

--- End quote ---

One of the effects I noticed when I went to CFL many years ago and later LED lighting is that I no longer noticed momentary dips in the power except if I had the bathroom vent fan on I would hear the speed sag momentarily and now I have several UPS's that kick in. Used to be every time the fridge or air compressor started or a tree branch landed on a power line somewhere the lights would dim or flicker. Modern lighting rides it out without so much as a flicker. I've even had a few incidents during wind storms when the voltage dipped to maybe 80V (from 120 nominal) for a full second or two accompanied by the loud buzz of an arc off in the distance and the LED lights didn't even dim. I only noticed it happening because it was around the holidays and I had some old incandescent Christmas lights around the window and those very noticeably dimmed and flickered.

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We had a proper brownout here for a few seconds and my computer SMPS didn't even blink.  The LED lights stayed on without dimming but both monitors, my GW Instek PSU and my scope rebooted (both are universal voltage 100-265V),  but the PC rode through without a blip.

Modern SMPS power supplies are quite comfortable accepting inputs well outside their nominal rating for some time, provided they aren't heavily loaded.  It's one reason I'm not convinced tap-changing UPSes are worth the money any more.
james_s:

--- Quote from: tom66 on December 28, 2020, 05:59:01 pm ---I can't see how voltage reduction would help with the majority of appliances.

Devices like dishwashers, washing machines, etc. all draw heating current to meet a temperature set point, so lower voltage will simply extend their heating cycles.  I^2 losses in feed cabling will reduce,  but this may well be counterbalanced by the losses of the machine being greater as the respective cycles operate for longer, losing more energy over that time.

The same applies for the cooling cycles of refrigerators, although perhaps the start-up current would be mildly reduced, I can't see this being considerable.

Anything with an SMPS will generally be more efficient at higher input voltages, although the difference between 230V and 245V is likely to be negligible.

In fact the only thing I could see an improvement on would be devices using fixed AC to accomplish a task with no feedback - fans, incandescent lights (do people really use these any more?) and maybe certain inexpensive LED lamps.  Almost everything else will be about the same, or better, on higher input voltages.

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Doesn't the current draw of an induction motor increase as voltage is reduced? Assuming that's the case then I^R losses in the motor windings and supply wiring will be increased. I was under the impression that the reason for the voltage increasing over the years from the original 110/220V to 115/230, 117/234 and the current 120/240V was to squeeze more capacity out of the existing grid and reduce transmission losses.
james_s:

--- Quote from: tom66 on December 28, 2020, 06:50:40 pm ---Modern SMPS power supplies are quite comfortable accepting inputs well outside their nominal rating for some time, provided they aren't heavily loaded.  It's one reason I'm not convinced tap-changing UPSes are worth the money any more.

--- End quote ---

I was discussing those with an engineer friend a few months ago after we each happened to acquire a pile of older UPS's. I'm not convinced the "automatic voltage regulation" models as they're called were ever worth it. They don't work like a constant voltage transformer, they don't even have very many steps, just a couple of buck and a couple of boost taps in most cases. The quiescent draw is significantly higher than a similar UPS without that feature since the transformer is active all the time and brings with it the associated losses. It's only a few watts but it can add up to megawatt hours over the life of the unit(s). Perhaps some areas have real brownouts that last many minutes, I don't know, but my power has only ever dipped out of spec for a stretch of a few seconds at most, or gone out completely. If the voltage goes out of spec I just want the UPS to kick in and switch to battery until things settle down. It's pointless for it to try to boost the voltage up. On top of that, if everyone had auto voltage boost regulators they would only exacerbate a brownout caused by overload since they have to draw more current from the grid in order to boost the voltage. The advertise the feature as beneficial for "sensitive electronic devices" but what electronics made in the last 30-40 years are "sensitive"? My family's first PC in 1984 had a switchmode power supply, it had a 115/230 selector switch on the back so it was not the modern type but I bet it would still operate reliably from say 90-140V. 
Zero999:

--- Quote from: SilverSolder on December 28, 2020, 06:13:49 pm ---My house is still full of incandescent lamps - they are all on dimmers and last, and last, and last...   and provide the warm glowing orange light I like when dimmed!  They are dimmed 99% of the time and not cost effective to replace.

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The efficiency of incandescent lamps drastically degrades when dimmed, so if you could get LED lamps with the same colour, as your dimmed incandescent lamps, you could get the same light for well under a tenth of the power.
schmitt trigger:
The only instance where a voltage reduction would be beneficial, is on home appliances which utilize permanent-split-capacitor induction motors.
More so if they were running at light mechanical loads.


But most modern appliances have moved or will move towards BLDC motors. Since their controllers are at heart a SMPS, the efficiency gain by a slight voltage decrease most likely will be minuscule.
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