Re: Why 60 Hz

["Dodge, Merrill SLC" <MDodge -at- SLCPO2 -dot- SLC -dot- UNISYS -dot- COM>]

>I can't remember all the reasons, but 60 Hz was arrived at after careful
>deliberations based on the factors of the era. (Probably has to do with
>synchronizing of a network of power stations.)

The AC standard was chosen for efficiency's sake.

Remember P=IxE; Watts=Amperes X Volts

In order for lines to carry the amount of DC power at the voltages required
by a community, the transmission lines would need to be FEET thick and
MEGATONS in weight. They would be too heavy for standard utility poles. But,
by using AC and step-up/step down transformers the voltage could be cranked
up to 100's of 1000's of volts and the current would stay low to deliver an
equal amount of Power.There would be lower line losses because less current
is transmitted. And we save Trillions in materials.

Sixty-cycle (Hz) is convenient for the ability to synchronize to standard
time. A simple AC motor, like in your wall clock, running on 60Hz household
current rotates 60 times a second because it's internal fields change
polarity at the rate of the input current. This is geared down to one
revolution per minute...geared down again to one revolution per hour (See
mickey's hands for an example).

You can speed up or slow down these kinds of clocks by changing the
frequency. Do this at night in and industrial site and you can make the
adjustment for Daylight Savings Time without touching a clock.

Televisions use the 60hz line frequency for vertical synchronization.

All in all, AC was a pretty good idea.

Merrill Dodge
gmd -at- unislc -dot- slc -dot- unisys -dot- com