When I was working on a job with high voltage (12500 volts), we came across a feature of electricity that has a lot to do with how we use electricity today.
Electricity is produced in two forms. We use the terms describing these two forms almost every day without realizing how they effect the electric power we receive.
DC power is direct current. AC power is alternating current. Generally when we use DC power a battery is involved. Alternating current means that the current travels back and forth at a certain rate of speed. One of the more common rates of speed is 60 times a second.
On the job with the high voltage (12500 volts), when we turned on the power to the 12500 volt 60 cycle (60 cycles per second) circuit it blew the fuse. There was no power load on the circuit when we powered it up. Upon investigating the cause, we were informed that the fuse had blown because of harmonics.
I was completely buffaloed! How would harmonics trip a fuse when there was no load. In fact, for that matter, what was harmonics? Today I still do not completely understand it. Since that time I have learned that as the electricity cycled back and forth 60 times a second, a small amount of electricity would lag behind. The lag was what was referred to as harmonics.
Instead of the power being at a regulated 240 volts some of the lag (harmonics) would be at 2 volts and some even less than that. It seemed to be in thirds. – a third harmonic, a sixth harmonic, a ninth harmonic (this is where I get lost).
Lately people that know this stuff very well have used the measurable harmonics for control wiring. Thus we have arrived at the age of electronics, computers, etc.
Some electrical experst understand this stuff and can explain it more thoroughly and correctly.
Perhaps this is the reason I have such a difficulty in using a computer, e-mail, face page, twizzler, etc. etc. etc.