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.

Comments

Re:DC power?

[AmiMoJo]

That's it exactly. Back then things like frequency conversion and DC level switching had to be done mechanically. To change frequency you ran a motor that drove a gear that drove a generator at the new frequency, and did something similar for switching DC voltage levels.

Nowadays high voltage DC is used widely for transmission. Everything is solid state and highly efficient.

Re:What Voltage?

[jenningsthecat]

Voltage doesn't kill; current kills and power burns. Higher voltage means lower current, and the same power.

Higher voltage only means lower MAXIMUM current, and then only if you assume constant power. However, it doesn't take much current to kill a person, and most real-world power sources can deliver enough current to kill under the right circumstances. (A mostly-dead flashlight battery can stop your heart if you bury electrodes deep enough in the right part of the body Also, think of Tasers - basically, low battery voltage raised to the point where it can stun or kill). Higher voltage usually makes death more likely, given the (approximately) constant resistance of a given current path through a body; I=E/R, so if E, (voltage) goes up, so does current. (Unless you're talking about static electricity from your clothing, or some other source which has high internal resistance/impedance and/or a small quantity of charge). And at still-higher prolonged voltages, the body's resistance can drop dramatically as parts of it start to boil and carbonize).

Your heart will fibrillate at 50mA AC or DC...

No. AC at a low enough frequency, (and at a surprisingly small current) will make the heart fibrillate; DC simply locks the heart muscle into a prolonged contraction. That's why defibrillators use DC - they temporarily 'freeze' the motion of the heart and give it chance to stop fibrillating and start beating normally.