Is high frequency alternating current (like 20khz) safer then standered 60hz ac for high voltage electricity?

Question

I heard higher frequency alternating current won't electricute someone if someone were to touch a high voltage live wire because of skin effect. Does this make higher frequency AC safer? If so why wasn't the power-grid used at that frequency instead of the existing lower one? If (ignoring the costs of upgrading power equipment) the powergrid was changed to have a higher frequency would that be more effiecent (not only safer) then today's 50-60hz ac?

Answer 1

Any frequency much higher than 60 Hz and losses get too high when power is sent long distances over wires. Each foot of wire has capacitance to other wires and ground, and has equivalent series inductance. These all cause losses. And the losses are proportional to frequency, so if you double the frequency, the losses double. In fact, the losses may be proportional to a higher power of f, perhaps close to frequency squared, since you have both capacitive and inductive losses occuring.



You might make the argument to use DC for long and medium distances, as high voltage DC to AC and AC to DC conversions are possible (but were not possible 50 years ago). But still very expensive and of low efficiency. But perhaps that will change...



But 20 kHz is too high for even transmission along a street and throughout a house.



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Answer 2

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RE:

Is high frequency alternating current (like 20khz) safer then standered 60hz ac for high voltage electricity?

I heard higher frequency alternating current won't electricute someone if someone were to touch a high voltage live wire because of skin effect. Does this make higher frequency AC safer? If so why wasn't the power-grid used at that frequency instead of the existing lower one? If (ignoring...

Answer 3

High Frequency Alternating Current

Answer 4

I don't believe that higher frequency AC is any "safer" then 50-60 HZ frequency. The problem with 60Hz frequency is that It is very close to the frequency at which your heart beats. That by itself can cause your heart to stop when you are electrocuted. If anything the high frequency is more dangerous because the voltage is going to peak a lot faster at a high frequency then it will at a low. Also your house appliances will only work on 60Hz. If your plugged your hair dryer into a 20khz outlet it would immediately blow up.



Im still learning though so if i am wrong anyone feel free to correct me.

Answer 5

60 times per second the voltage is zero. Many types of control equipment take advantage of this. For example: It allows a heating element to use 20 of the 60 cycles instead of using a rheostat which increases resistance and absorbs voltage .More importantly electric motors and generators that work at a lower Hz are easier to produce.

The power grid is based on economical generators.

Answer 6

I have a problem with your use of the term 'Skin Effect".



Skin effect is the tendency of an alternating electric current (AC) to distribute itself within a conductor so that the current density near the surface of the conductor is greater than that at its core. The skin effect causes the effective resistance of the conductor to increase with the frequency of the current because much of the conductor carries little current.



Regardless of the frequency, the outside of the conductor is at full potential.



Efficiency of the grid is related to frequency, but the lower the better. The generators are also much simpler and operate at acceptable speeds.

Answer 7

I think your confused as to the difference in uses of frequencies. The normal frequency or 50 hz (Europe, etc) and 60 hz (USA) are used because of copper/power. High frequencies are used mostly in communications, lower in power generation.

Answer 8

I think everyone else is right. Nobody is safe on here. Just when you think you might be.... the trolls come in and report you for no reason or the thumbs down police follow you around. Oh well, all you can do is try to ignore them and have fun anyway.

Answer 9

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