Anyone else doing AC Electrical research?

[Rich Bayer]

I do a lot with generators at work and we also share the “house” with high voltage exterior/Airfield electricians as I work on an airport (Small, not busy Guard/USCG base.) Stuff Id on’t know much about (mechanically) has been a real bug-light to me. So I’ve been looking up AC electrical basics.

I found a couple videos and I’ve got a grasp on the basics, but I’ve hit a bit of a wall now where I can’t find anything more without it jumping to an extreme level. Engineers, Power systems math equations.. etc etc.. I’m horrible with math..

Anyone else have any links they/we would like to share? I’ve had my head in DC-land since the 90’s so this is quite a challenge to grasp AC now.

Again, I have a grasp on the basics, but I need some phase info, Parallel-series stuff, Generator theories other than the basics. Maybe home wiring basics will help? What a “common” wire?

This one is old but really helped!

Topic

[twiggy]

That’s a great video thanks for sharing it. I’m not sure how deep you want to get into it because you can study this forever and still not learn it all. Another fun fact is that any shape of waveform including switching dc voltages can be represented as a sum of several harmonics of sine waves, this is called Fourier Theorem. So ac theory is really the heart of almost everything and is good that you desire to learn it.

[college man]

see if any of this helps.

http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems

[Rich Bayer]

^ Eh.. I’m pretty well versed with automotive DC stuff but thanks for the link. I’ll poke through anyway.

I’m not looking to get into the math end of AC or even the seriously technical electronics end of it. I’ve gone into DC FET transistors and power supply stuff in Oshkosh school. But I’m mostly looking to learn to be comfortable doing stuff around the house, for one. I’ve learned black is “negative” white is hot, green is ground, red and (yellow?) are phase… I get what phases are and why our US 60hz frequency is important. I just seem to have a lot of spotty information from a little beyond basics. I’d like to be more effective at work with the generators as well, but I guess it’ll come with time. I threw my hat in the ring for being the guy that takes care of them since we have so many it’d be a full time job. (20kw to 200kw) I’m already the equipment mechanic, but me just taking all of the generators under my wing would simplify things once this new guy comes in soon.

Come to think of it… I wonder if I could take apart the old 20kw in the corner of the shop. My work leader and I have been wanting to learn more about AC and I’ve got a slight bit of a lead on him as far as this goes.

[Paul]

[quote=”Bayer-Z28″ post=94245]I’ve learned black is “negative” white is hot, green is ground, red and (yellow?) are phase…[/quote]

Kinda. You’re on the right track. Black is hot, and white is neutral – it’s counterintuitive to me also. Neutral is usually at zero Volts and should be tied to ground at somewhere in the circuit . The green ground wire is a backup to earth ground to prevent shock. AC current is a different in the sense that current oscillates back-and-forth in the wire. When the voltage swings negative, the current changes direction, and the current can still perform work. An incandescent lamp doesn’t care which way the current flows through the filament, nor if the current switches direction 60 times per second. It will illuminate as long as current flows through the filament.

With 3 phase power, there are 3 hot wires, one each for each phase, and a single neutral wire. I don’t remember the color codes for the wiring.

The utility connection to your home is 240V single phase (in the US), but they use a trick known as split phase to get 120V. One connection scheme gives 240V single phase, to power an electric dryer for example. A different connection scheme will yield two separate 120V single phase (i.e. hot) lines that are out of phase with each other.

http://upload.wikimedia.org/wikipedia/en/2/29/Split_phase2.png

[quote=”Bayer-Z28″ post=94245]…why our US 60hz frequency is important.[/quote]

I am amazed that we can synchronize all of the elements in our power grid that well. It doesn’t take much for the system go sideways.

I hope that helps.

[Rich Bayer]

This is the basics stuff that I’ve been looking for.. Thanks a ton.. I’ve got a bunch of pieces and I’m starting to put them together. I also looked up AC induction motor stuff last night and starred at a picture of the three phase wiring schematic until I understood it. :blink: :woohoo: Blue black and green is what this guy used.. Home made setup with 48 volts and about 500ma.

I told my work leader at work today that I’m going to take aapart the generator in the corner of the shop. It’s a 1993 model (I think.. or 1998).. was on one of the pickups on one of the leads. Was a single phase 240 200kw generator. I started tearing into it and my electrician buddy told me to run it before I get to far into it so we can see what the problem was and why we pulled it out. Come to find out, they thought there was something up with the frequency (How is that even possibly for it to make 245v and not have a frequency??)… It was making 243 at the breaker coming out of the head, but the Frequency gauge was dead. I got 61.4 at the back of the gauge. Oh well.. The breaker was questionable too.

I had it “bench running.” Running off a gallon of fuel in a jug, and a somewhat dead battery out of a backhoe I serviced a couple weeks ago.

(I also have many camaro videos on that channel too… 😀 )

[Lorrin Barth]

I’m no math major by any means. I’m doing good to balance my check book. And I spent the last twenty years of my life dispatching power at an electrical utility.

Everything seems hard when you are starting out but that really is the fun part. That is where the adventure lives. Enjoy.

[Author]

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