log said:
Supposed our alternating current jumps from 60 Hz to
1 khz or 1 Mhz. What would happen?
First, our power grid would not work so well. The inductance of the lines
is already bad at 60Hz, and would be 16 times worse at 1 khz.
Probably nothing will work at 1 Mhz, except maybe heaters, and even this
depends on the reactive component - 1 MHz is just too far from the normal range.
What appliances would be damaged? Or would the fast
fluctuations average to a DC such that the electric
fan would no longer run? Suppose you increase the
frequency of the AC to just say 200 Hz. Will the
electric fan still run? Or will it run so much faster?
How about light bulbs and flourescents?
If you can get it to your house, some stuff will work at 1 khz and some
not. Incandescent lights and heaters should work fine. Stuff with simple
switching supplies (laptops and other things with power warts) may work.
There is no problem in theory (they do AC->DC->AC->DC) but the input filters
might be tuned to 50/60 Hz. Stuff with transformers may well work depending
on the exact construction. (At HP, back when most instruments had transformers
we tested almost all our products at 400 Hz, and they worked well in general.)
Flourescents might come on but will be dim since their ballasts are
inductive. Most motors will not work at all for two reasons; they depend on
the frequency to set their speed and cannot run 16 times as fast, and the
inductive winding will let less current through. Basically you would need to
look at each piece of equipment to see if it would work, or be damaged.
Finally, the audible noise will be horrible. The ear is much more sensitive
to 1 khz than to 60 Hz, especially at low volumes.
Just want to understand the significance of frequency in power lines. Thanks.
It's a tradeoff; higher frequencies can use smaller and lighter power equipment
such as transformers, filters, and capacitors, but low frequencies are easier
to ship long distances, and more convenient for rotating machinery such as
motors and generators. So airplance, were weight is important and wires are
short, use 400 Hz. Spacecraft, where weight is really important, use 2.4 khz.
