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Sharp Announces Sales of DC Powered Air Conditioner, Other Products To Follow
AmiMoJo writes: Sharp has announced that sales of DC powered air conditioners will begin by the end of the year. Most appliances use the standard AC electricity supply in homes, but as solar panels become more common switching to DC can save on conversion losses. Solar panels produce DC, which is then typically converted to AC before being fed into the house's wiring, and then converted back to DC again by appliances. Sharp has announced that it intends to produce a range of DC powered appliances for home use.
The main advantage of AC is that you can use higher voltages safely, and higher voltages mean higher wattage with the same wires. And bigger wires are more expensive.
AC versus DC load breaking comparison with a knife switch
That was 220 volts, but 110 volts isn't much better on the DC side. There's a reason why DC-powered telecoms equipment uses 48 volts; much more than that and switches start arcing.
Ohmic loss is an issue when DC power is transmitted over power lines, but not so much when the DC is generated in the same building (solar panels, etc.).
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
Well, here you have 350 kV / 700 MW thyristor converter. It's easy to find, because it's pretty big. ;-)
http://new.abb.com/systems/hvd...
https://en.wikipedia.org/wiki/...
Basically, Sharp is eliminating the rectifier circuit from one of their existing products. Sharp currently sells it as an 'Inverter Air Conditioner".
Unlike most air conditioners, inverter air conditioners are always-on. The inverter varies the -frequency- of alternating current sine wave in order to change the cooling output of the air conditioner. It continuously outputs just enough cooling to maintain a steady temperature in the room.
To do this, the A/C converts the incoming wall power to DC and then back to variable frequency AC. Eliminating the initial AC to DC conversion here makes good sense.
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
High Voltage DC transmission makes sense in some applications. Its best as a single point to point solution over a fairly long distance, as line losses are minimized. High voltage DC switching and DC to AC conversion equipment is very expensive compared to AC, and typically has a shorter lifecycle, so you don't really want to have a lot of DC switchyards.
High AC voltages have induction losses. They don't travel as well as low voltages.
BUT
The goal is to send lots of watts, not lots of amps or volts. Low amperages travel well. High amperages don't travel at all -- they lose most of their energy to heat. Simple transformers (which are basically just coils of wire) can swap amps for volts so that lots of watts can travel a long distance at low amperages.
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
It's called an "inverter" air conditioner. It produces a variable-frequency AC sine wave from the DC voltage. The variable-frequency to the compressor changes the cooling output, so instead of turning the air conditioner on and off as the temperature wanders back and forth across the set point, it varies the frequency to keep the temperature steady.
http://www.acson-international...
https://en.wikipedia.org/wiki/...
It is brilliant.
Sharp already sells these air conditioners. They're just removing the DC rectifier circuit and running directly on DC instead of starting with 50hz or 60hz AC.
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
They use inverters to convert the DC to some square wave and approximate it to A/C using electronic gimmicks. Not a pure sine wave A/C, but close enough to run fans and the lamps. Energy conversion efficiency is not bad, the inverters do hot heat up too much. But they play havoc with the motors. So the Japanese A/C makers have been selling ruggadized air conditioners that can run on the inverter electricity.
The logical next step is to create A/C to run purely on DC. Probably it would use AC to DC converters to use grid electricity. Again this DC would be poor in quality compared to battery DC. So this Aircon also would need to be ruggadized.
All these calculations about when residential solar will become viable compared to coal or natural gas are completely different between G8 and rest of the world. Places like India will pay well over the current grid price for steady electricity supply. Not all of them. But the affluent population of India is about the size of Japan, some 120 million people. They have been making do with truck-battery-inverter contraptions, small gasoline generator sets etc. They would probably form the wave of early adopters who pay for the early fixed costs of solar panel factories.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
DC can be problematic in that you can't always detect certain faults as there is not ground fault current, so there is inherently some greater chance of something like a bad connection overheating and causing damage, but that should not really be a concern if stuff is quality and installed correctly.
There's no connection between ground faults and bad connections that might cause overheating. But to the extent that DC systems might have lower voltage and therefore higher current, bad connections ARE more likely to overheat and cause fires. Also, there's no reason a properly installed DC system can't have Ground Fault Interrupters, although the ones currently used for AC won't work on DC. The ones designed for DC would be somewhat more complex, and probably bigger as well.
Another note: interrupting Direct Current without arcing can be difficult. AC has a zero crossing that extinguishes an arc across switch contacts, whereas the equivalent DC circuit may continue to arc across switch or relay contacts. Such switches and relays typically have heavier contacts and the contacts, when open, tend to have more space between them. The may also have permanent magnets nearby to act as 'blowouts' to extinguish any arc that develops.
'The Economy' is a giant Ponzi scheme whose most pitiable suckers are the youngest among us and the yet-unborn.
Early Southern architecture had passive cooling systems, like double-hung windows, high ceilings, and constructing doorways and windows in such a way as to generate breezes as the air heated up during the day. The Spanish were particularly good at things like this.
Folks also had a different daily routine. They were up before the sun, worked until about lunch, had a big meal and a nap during the hottest part of the day, and then worked until late in the evening. The Spanish siesta is a good example of this, but the Italians have a similar concept. In modern days I see a lot of construction workers doing this too, particularly on road construction. The job site will be empty during the afternoon and work begins in the evening and lasts all night. (Some of this is to keep from interfering with day-to-day traffic patterns too.)
Only two things are infinite, the universe and human stupidity, and I'm not entirely sure about the universe - Einstein