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Posted: Mon Jan 21, 2008 2:27 pm
I will try it tonight

Posted: Fri Jan 25, 2008 3:15 am
i have to disagree about this "two phase" thing for an electric dryer...220 really is a single phase, the sinewave is split in half by the nuetral , and "two phase" only applies when you have a 220 , and a 110 tap. but then it is using a split phase tap which means that the appliances 220 components are running on the full phase, where as the 110 components are running on 1/2 the voltage 1/2 the phase as the 220 components. it's split phase not "two phase"..

-------phase A--------goes to "hot" side of coffee pot-----

GND---------------Goes to ground lead of coffee pot--

-------phase B--------goes to "nuetral" side of cofee pot--

remember that voltage is actually electrical differential .....if you could think of your fusebox like this you have one side that is +110 volts and because it is alternating phase the other at the same time is -110 volts and vice versa.

Posted: Fri Jan 25, 2008 4:58 pm
True 2-phase electricity requires that the neutral be twice as big as either one of the other conductors.
I was always taught that the european wire code used BlUe/PUrple as the neutral wire as it is usually the only other color that has a "U" in it as our ne"U"tral does.

Bear

Posted: Sat Feb 02, 2008 9:52 am
"True 2-phase electricity requires that the neutral be twice as big as either one of the other conductors."

Why would that be? Worst case would be max current on one phase and zero current on other. When currents in both phases are equal, then neutral current is zero.

Posted: Sat Feb 02, 2008 10:19 am
Greetings Bear,
dyarker wrote:"True 2-phase electricity requires that the neutral be twice as big as either one of the other conductors."

Why would that be? Worst case would be max current on one phase and zero current on other. When currents in both phases are equal, then neutral current is zero.
You are correct when the two phases are 180 degrees apart,
which is the case for "split-phase" 120/240V service in North
America.

Perhaps the comment was directed at two phases of a three-phase
supply, where the phases are 120 degrees apart, or an
arcane two-phase systemwith 90 degrees between phases?

Posted: Sun Feb 03, 2008 9:15 am
Peter... Yes I was refering to the arcane(?) system. Thank you for digging up that explanation of "2 phase" electricity. I was wondering how I was going to explain it. Arcane ? maybe. Up until some years ago there was a machine/metal fab shop in Oakland, CA that used motors that spun the shafts with the pulleys on it that fed the belts that powered the machines.
Walking into Jerry's shop was walking back into the late 19th./early 20th. century.

Take care all!!

Dennis

Posted: Sun Feb 03, 2008 8:45 pm
Conversion between 2 phase and 3 phase power can be done with a transformer connection called a "Scott T". I suspect that most power distribution was done with 3 phase power, and that individual users would convert it to 2 phase power if it was needed.

I have seen several reprints of books on lathe operation published around 1940 that still showed lathes using belt drive from overhead shafts. Some of the lathes were powered by individual motors mounted behind the lathe, but still with a belt drive. I would guess that a machine shop established before 1940 would have continued to use the old equipment for several years after because of the scarcity of new equipment in World War II and the money invested in the tools already bought.

Posted: Mon Feb 04, 2008 4:31 pm
Greetings Dennis,
Bear wrote:Up until some years ago there was a machine/metal fab shop in Oakland, CA that used motors that spun the shafts with the pulleys on it that fed the belts that powered the machines.
Walking into Jerry's shop was walking back into the late 19th./early 20th. century.
I didn't realize the Bay Area had anything that old and still
in place. Actually, now I think about it Livermore has the