electricity 101

[cadpoint]

hey guys
Assuming a PF of 1 .... is cheating.

As well as we might all think 100%, Go for it daily...

Gar: please don't say statements your don't want to talk about, what the fun in that ? !

I really wanted to argue the DC state of power, as to what makes it intermittent by its usuage, I'll even throw in a PF factor...

 

[K8MHZ]

So now we have a new question: We may accept that in order for something to be called AC, the waveform must have zero crossings. Is that the current waveform, or the voltage waveform, or both?

You do pose an interesting question. But since AC means 'alternating current' my bet would be (are you ready for this?).....the current waveform.

I still feel since the issue of AC vs. pulsating DC initiates squabbles among the learned and informed that pulsating DC should have it's own category.

When you spoke of the effects of capacitors in PC (my very own acronym) vs. AC did you consider the differences between standard and electrolytic capacitors? A rechargeable battery is very similar to an electrolytic capacitor. It *can* be recharged with PC, but *not* with AC.

Just some more food for thought. Thanks for your input, I appreciate it.

 

[quogueelectric]

Actually, an ignition coil is an auto-transformer.

Come to think of it, it's an auto transformer. :grin:

I thought they stopped making them the year of the flood. I think it is individual coil packs one per cylinder from this point. These high energy ignitions will produce as high as 80k volts open circuit. I found this out the hard way as it was blasting through my 5kv insulated linemans through my sneakers and back up the tires to the engine. I didnt know what hit me until I put it on a scope and saw the open ckt voltage trace at about 60-80k.

 

[76nemo]

Thanks for the heads up to the show on the History channel. I will call them soon to see if I can buy a copy. I have read Edison's studies as well as Tesla's and Westinghouse's, but until I saw it on video, they never came across as that eye opening!!!!!!!!!!!!!

Talk about brilliance!!!!!!!!!!!

There has been talk around here about utilizing EMP for Sheriff's and State troopers for stopping cars in high speed chases, it gets shot down every time.

That show just urged my intent for further knowledge 10 fold. Tesla had it all figured out before the 1900's. I am in awe. I wish it came to me THAT easily!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[K8MHZ]

Thanks for the heads up to the show on the History channel. I will call them soon to see if I can buy a copy. I have read Edison's studies as well as Tesla's and Westinghouse's, but until I saw it on video, they never came across as that eye opening!!!!!!!!!!!!!

Talk about brilliance!!!!!!!!!!!

There has been talk around here about utilizing EMP for Sheriff's and State troopers for stopping cars in high speed chases, it gets shot down every time.

That show just urged my intent for further knowledge 10 fold. Tesla had it all figured out before the 1900's. I am in awe. I wish it came to me THAT easily!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The show only scratched the surface of Tesla's genius. If you get a chance, pick up the book 'Tesla, a man out of time'.

 

[gar]

080514-2124 EST

cadpoint:

Look at the thread on single phase vs three phase and hold long it is and going nowhere. I tend to accept a definition AC that is appropriate to the application.

Here are some more comments I started earlier:

080513-1344 EST

K8MHZ:

I believe there are different points of view about the definition of alternating current.

From:
http://dictionary.reference.com/browse/alternating current
One definition says

"An electric current that repeatedly changes its direction or strength, usually at a certain frequency or range of frequencies. The term is also used to describe alternating voltages."

Note the use of "or strength"

From the same web site

"An electric current in which the flow reverses periodically. "

If I have a sine wave of Vp=10 V and add a variable DC component to this, then by your definition this is AC until the DC component is greater than or equal to 10 V. If this input is coupled thru a capacitor to a resistor, then independent of the DC component as I adjust the DC value I have exactly the same AC signal across the resistor.

Really the definition of AC is probably somewhat application dependent.

The DC component of a varying input to a capacitor is of no importance until you encounter breakdown of the capacitor. In the case of a transformer a DC component is important because it drives the core more into saturation in one direction as the DC component is increased in one direction.


On to filament failure. A 757 pilot lamp was originally rated at 50,000 hrs by GE, later reduced to 5000 hrs. This is a thin filament. My own experience with many of these operating on DC vs AC was much shorter life on DC.

Some references:
http://www.wamcoinc.com/Oshino/Oshino_lamps-Overview.htm this one is particularly good

http://www.harison-toshiba.com/lampinfo.htm
http://www.freepatentsonline.com/3759602.html

.

 

[zog]

Thanks for the heads up to the show on the History channel. I will call them soon to see if I can buy a copy. I have read Edison's studies as well as Tesla's and Westinghouse's, but until I saw it on video, they never came across as that eye opening!!!!!!!!!!!!!

Talk about brilliance!!!!!!!!!!!

There has been talk around here about utilizing EMP for Sheriff's and State troopers for stopping cars in high speed chases, it gets shot down every time.

That show just urged my intent for further knowledge 10 fold. Tesla had it all figured out before the 1900's. I am in awe. I wish it came to me THAT easily!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The show just covered a few points, for the whole story I highly recommend reading "Emipres of Light"

 

[K8MHZ]

I believe there are different points of view about the definition of alternating current.

There is no question about that. That is why I am in favor of adding a third type to describe an electrical supply that varies without a change in direction.

I think a further question to ask is 'who (person or entity) is it that decides the exact definition?' As we have demonstrated here, the definition of AC will vary from source to source.