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#11
posted to rec.boats.cruising
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Half the amps?
On Sat, 7 May 2011 13:10:22 -0400, "Wilbur Hubbard"
wrote: "Bruce in Bangkok" wrote in message .. . On Fri, 6 May 2011 11:47:56 -0400, "Wilbur Hubbard" wrote: "Stephen Trapani" wrote in message ... On 5/5/2011 12:44 PM, Stephen Trapani wrote: On 5/5/2011 10:43 AM, Wayne B wrote: On Thu, 05 May 2011 10:02:55 -0700, Stephen Trapani wrote: I think Larry once explained why the amps get cut in half, but I forgot. I have an amp meter installed in line between the alternator and the battery switch. Last weekend I had a borrowed Fluke clamp meter. When I put the clamp on the line coming out of the alternator it read exactly half of what the in line amp meter was reading. Why is that? Sounds to me like an inaccuracy in one of the meters. Do I understand correctly that you are clamping the Fluke around the one and only wire delivering power from the alternator? Yes. Do you have the Fluke switched to DC amps, and on the correct scale? Yes. I'll ask the guy who loaned me the Fluke to be sure. I called Fluke. The setting I used was supposed to give me straight DC current. So...mystery NOT solved. Where's that damned Larry when you need him??? Stephen An alternator puts out Alternating Current which runs through a bridge rectifier which rearranges it to pulsed Direct Current. Pulsed DC is not real DC. That meter will only read right on loads from the battery. Try it on a lead from the battery to the load and I bet it then reads correctly. Larry wasn't as smart as me. . . Wilbur Hubbard Ahhh Willie-boy. Do you sit up nights studying or are you naturally this stupid? DC electricity is a form of electricity where the electrons all move in the same direction ( from an area of negative (-) charges to an area of positive (+) charges). AC electricity is a form of electricity in which the polarity reverses and therefore electrons flow one way during half the cycle and the other way during the other half. Pulsed DC is simply a DC current that is switched on and off (pulsed) it IS NOT A NEW FORM OF ELECTRICITY. An alternator produces AC electricity and an automotive type "alternator" produces DC electricity by converting or rectifying the AC current into DC current. It does this by using "diodes" which are a little two legged gizzy that can be thought of as one way electrical valves. Connected one way they conduct only during the positive portion of the AC wave and if connected "backward" they conduct during the negative portion. A bridge rectifier is simply 4 diodes with two connected to conduct during the positive portion of each side of the alternating wave form and two conducting during the negative. This gives the smoothest DC form possible in a simple DC circuit from an auto type alternator. Now, if you connect the positive lead of your meter to the alternator output connection and the negative lead to ground you will read the output voltage of the alternator, not some idiotic and fictitious Pulsed DC that Willie-boy talks about. Why? Because while the DC current is actually fluctuating it is doing so fast that you meter can't react quickly enough and so reports the correct effective voltage. Most DC stuff doesn't care what it gets as long as it all comes from the same direction. When the pulsed (so fast you can't measure it with your meter) DC reaches the battery it charges it just as though it was pure, filtered DC. So. If you are interested in a DC circuit stick your meter on it and read the voltage, don't get all wound up in pulsed DC and all the other weird things that Willy-boy comes up with. Amps and volts: Power is measured in Watts which are the amperage used in the circuit times the voltage in the circuit. If you have a 12 volt light bulb and it draws 2 amp then you have a (121 x 2) 24 watt light. Change the amperage or the voltage and the power (Watts) change. 12 Volts X 4 amps = 48 watts 1 V X 4 A = 4 watts. 1000 V X 0.048 A = 48 watts. and so on. Cheers, Bruce (bruceinbangkokatgmaildotcom) Hey moron! Forget about voltage - we're discussing measuring amperage in this thread. No Willie-boy you were talking about your fictitious Pulsed DC. I was simply demonstrating that once again you don't know what you are talking about. You have proven how dumb you are again, Bruce. Your talk about connecting a volt meter in parallel is correct but an amp meter does not connect to positive and negative leads. You'd burn it out doing that. Amp meters connect in series. The type of amp meter we're discussing here in this thread doesn't connect at all. It consists of a mechanical jaw your run the insulated wire through. It reads the magnetic field and converts it into a current reading. (amps) So, why the heck are you trying to misdirect with your voltage nonsense? My goodness, you are talking about a clamp-on amp meter, just like the ones I've been using for 30 years or more. In a bridge rectified circuit, if you observe it on an oscilloscope, it will have a sine wave that is 'chopped' looking - not smooth. This type of sine wave doesn't produce as strong a magnetic field as a conventional smooth sine wave. A loop type amp meter will come up with an incorrect amp reading because of the rectified circuit that simply turns the alternating current so it all flows in one direction. The only problem with that is the short periods when the A/C turns around it stops completely for a finite period of time. The finite period of time is not eliminated by the rectifier. So you have a period of direct current then you have a short period of no current then a period of direct current and then no current. The magnetic field is not constant but rises and falls. The loop amp meter fails to read it because it's not calibrated to correctly measure this type of current that is not steady. You have just to learn to keep your mouth closed. When you observe the output from an internally rectified alternator the output is not a sine wave. A sine wave is described as "mathematical function that describes a smooth repetitive oscillation" and in electricity is used to describe an AC circuit. Since, as you have previously described, the AC generated in the alternator is converted to DC by rectification there is no sine wave as you describe. If you had ever looked at a oscilloscope connected to the output of an alternator you would have seen that the output is all pure DC. No sine wave at all. Obviously you have read about the output of a rectified alternator and didn't understand what you were reading. I can see no other reason, short of sheer stupidity, that would lead you to discuss sine waves in terms of a rectified circuit. Your final statement rather makes one lean to the latter however as a DC clamp on amp meter reads the output of an auto alternator perfectly well and while not perhaps giving laboratory accuracy certainly is used for the purpose by literally millions of electricians for exactly this purpose. In short Willie you discussed "Pulsed DC" as a third form of electrical current - 'taint true Then you state that a normal clamp on amp meter won't read the output of a rectified alternator - false again. Want to try for a third strike? Don't you ever get tired of me proving you don't know anything? Wilbur Hubbard I might if you ever did prove anyone wrong, however all you do is spread it deeper and further but the aroma remains the same. Cheers, Bruce (bruceinbangkokatgmaildotcom) |
#12
posted to rec.boats.cruising
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Half the amps?
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#13
posted to rec.boats.cruising
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Half the amps?
208 lines of repeat?
or was it only 199? #### ## ## #### ###### ## ## ## ### ## ## ## ## #### ### #### ## ## ## ## #### ### ## #### ## ##### ## ### ## ### ## ## ## ## ## ## ## ## ## #### ## ## #### #### ## ##### ## ## ## #### ###### ## ## ## #### ### ### ## # ## # #### ## ## ## ## ####### ## ## #### ## ## ## ## ####### ## ## ## ## ## ###### ## # ## ## ## ## ## ## ## ## ## ## ## ## ##### ## ## ## ## #### #### ## |
#14
posted to rec.boats.cruising
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Half the amps?
CaveLamb wrote:
208 lines of repeat? or was it only 199? #### ## ## #### ###### ## ## ## ### ## ## ## ## #### ### #### ## ## ## ## #### ### ## #### ## ##### ## ### ## ### ## ## ## ## ## ## ## ## ## #### ## ## #### #### ## ##### ## ## ## #### ###### ## ## ## #### ### ### ## # ## # #### ## ## ## ## ####### ## ## #### ## ## ## ## ####### ## ## ## ## ## ###### ## # ## ## ## ## ## ## ## ## ## ## ## ## ##### ## ## ## ## #### #### ## Well, at least you could spell Damn correctly. :) |
#15
posted to rec.boats.cruising
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Half the amps?
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#16
posted to rec.boats.cruising
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Half the amps?
Mark Borgerson wrote:
In article , says... 208 lines of repeat? or was it only 199? /compression on SNIP DAMIT /compression off Sorry---I forgot that some people have limited internet and new reading bandwidth. ;-) I'm so used to scrolling past the history on some other groups that I forgot that this group is usually a bit more concise. Mark Borgerson Golly, Mark, thanks for being so nice. THAT'S not normally part of this group. -- Richard Lamb http://www.home.earthlink.net/~cavelamb http://www.home.earthlink.net/~sv_temptress |
#17
posted to rec.boats.cruising
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Half the amps?
On 5/5/2011 12:02 PM, Stephen Trapani wrote:
I think Larry once explained why the amps get cut in half, but I forgot. I have an amp meter installed in line between the alternator and the battery switch. Last weekend I had a borrowed Fluke clamp meter. When I put the clamp on the line coming out of the alternator it read exactly half of what the in line amp meter was reading. Why is that? Stephen There are two kinds of clamp on ammeters - the ones good for AC only, and the ones that work for AC and DC. The AC only kind are cheaper, but they expect to find single phase alternating current. As several folks already mentioned, the usual Auto alternater uses an internal three phase full wave rectifier stack, which uses six rectifiers typically. Because adjacent phases overlap, the AC current component is rather less than half the peak current amplitude.Cheap AC clamp on meters read low in this situation. This story is all well and good, but you mentioned Fluke specifically, and I don't think they actually make the cheaper AC only clampons - but I could be wrong. Brian W |
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