On Sat, 3 Jan 2004 10:34:35 -0500, "BFoelsch"
wrote:


My absolute favorite was the 6 phase double delta. Picture a straight 220
(YES, 220, not 240) delta connection. Now, center tap all the transformers,
and these midpoints give you another delta at 110 for the lighting load. Of
course, the whole thing is ungrounded. Yes, all the light switches in the
building were 2 pole. Yes, the small motors were 110 volt 3 phase. This
system gives you 2 three-phase voltages out of one set of transformers, The
power factor transforms at unity, unlike many connections. Only thing is, it
is very had to protect the transformers unless you use 6 primary fuses.


Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that? Might it have been wired wye with one central
common/neutral? That seems more logical, but then maybe it wasn't very
logical.

Years ago, maintenance electricians had to be aware of a lot of varied
systems. Today, life is a whole lot simpler.

The thing that always amazes me is that buildings are wired in the
most bizarre ways, and no documentation is left behind. If you call in
an electrician, they figure it out somehow, kluge it some more, and
leave.

John

"John Larkin" wrote in
message ...
Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that?

Nope. Draw a picture of a Delta, center-tap each winding, and the three
center taps form another delta at half the voltage. Used a perfectly
standard (for 1922) 3 phase, 3 wire, 110v, 25Hz motor.

The 110 volt service made no connection to the corners of the 220 delta. The
110 delta was fed only from the center taps.

On Sat, 3 Jan 2004 14:10:54 -0500, "BFoelsch"
wrote:


"John Larkin" wrote in
message ...
Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that?

Nope. Draw a picture of a Delta, center-tap each winding, and the three
center taps form another delta at half the voltage. Used a perfectly
standard (for 1922) 3 phase, 3 wire, 110v, 25Hz motor.


Oh, yeah, OK. New Orleans is mostly below sea level, and the
Mississippi runs along most of it and peaks way above in the spring.
Up to fairly recently, New Orleans was drained by ancient pumps with
ancient switchgear, running on 25 Hz, and all the generators that made
the 25 Hz were (of course) in the city, below sea level too.

John

Clever, clever, delta, New Orleans.........................

And who said there's no wit here!

Yeah, 25 Hz has kind of pooped out recently. It is still generated on the
Canadian side of Niagara Falls, but it is all converted to 60.

Across the river in Buffalo, the utility still provides 25 Hz to about 50
customers, but they have announced its termination as of 2007. There are a
few isolated paper mills that make their own, I believe that Con Edison
makes a little, and there is one isolated pocket in Iowa, but that's all I
know of that's left.

I remember when 60, 50 and 25 cycle motors were all stocked items!

Thanks in advance.

"John Larkin" wrote in
message ...
On Sat, 3 Jan 2004 14:10:54 -0500, "BFoelsch"
wrote:


"John Larkin" wrote in
message ...
Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that?

Nope. Draw a picture of a Delta, center-tap each winding, and the three
center taps form another delta at half the voltage. Used a perfectly
standard (for 1922) 3 phase, 3 wire, 110v, 25Hz motor.


Oh, yeah, OK. New Orleans is mostly below sea level, and the
Mississippi runs along most of it and peaks way above in the spring.
Up to fairly recently, New Orleans was drained by ancient pumps with
ancient switchgear, running on 25 Hz, and all the generators that made
the 25 Hz were (of course) in the city, below sea level too.

John

I read in sci.electronics.design that John Larkin jjlarkin@highlandSNIP
techTHISnologyPLEASE.com wrote (in ke7evvo4mvalsj6km5ja2u4di666ge0g49@
4ax.com) about 'why 3-phase power?', on Sat, 3 Jan 2004:

Up to fairly recently, New Orleans was drained by ancient pumps with
ancient switchgear, running on 25 Hz, and all the generators that made
the 25 Hz were (of course) in the city, below sea level too.

Naturally: 25 Hz is an unusually LOW frequency.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

Clever, clever, delta, New Orleans.........................

And who said there's no wit here!

Yeah, 25 Hz has kind of pooped out recently. It is still generated on the
Canadian side of Niagara Falls, but it is all converted to 60.

Across the river in Buffalo, the utility still provides 25 Hz to about 50
customers, but they have announced its termination as of 2007. There are a
few isolated paper mills that make their own, I believe that Con Edison
makes a little, and there is one isolated pocket in Iowa, but that's all I
know of that's left.

I remember when 60, 50 and 25 cycle motors were all stocked items!

Thanks in advance.

"John Larkin" wrote in
message ...
On Sat, 3 Jan 2004 14:10:54 -0500, "BFoelsch"
wrote:


"John Larkin" wrote in
message ...
Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that?

Nope. Draw a picture of a Delta, center-tap each winding, and the three
center taps form another delta at half the voltage. Used a perfectly
standard (for 1922) 3 phase, 3 wire, 110v, 25Hz motor.


Oh, yeah, OK. New Orleans is mostly below sea level, and the
Mississippi runs along most of it and peaks way above in the spring.
Up to fairly recently, New Orleans was drained by ancient pumps with
ancient switchgear, running on 25 Hz, and all the generators that made
the 25 Hz were (of course) in the city, below sea level too.

John

I read in sci.electronics.design that John Larkin jjlarkin@highlandSNIP
techTHISnologyPLEASE.com wrote (in ke7evvo4mvalsj6km5ja2u4di666ge0g49@
4ax.com) about 'why 3-phase power?', on Sat, 3 Jan 2004:

Up to fairly recently, New Orleans was drained by ancient pumps with
ancient switchgear, running on 25 Hz, and all the generators that made
the 25 Hz were (of course) in the city, below sea level too.

Naturally: 25 Hz is an unusually LOW frequency.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

On Sat, 3 Jan 2004 14:10:54 -0500, "BFoelsch"
wrote:


"John Larkin" wrote in
message ...
Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that?

Nope. Draw a picture of a Delta, center-tap each winding, and the three
center taps form another delta at half the voltage. Used a perfectly
standard (for 1922) 3 phase, 3 wire, 110v, 25Hz motor.


Oh, yeah, OK. New Orleans is mostly below sea level, and the
Mississippi runs along most of it and peaks way above in the spring.
Up to fairly recently, New Orleans was drained by ancient pumps with
ancient switchgear, running on 25 Hz, and all the generators that made
the 25 Hz were (of course) in the city, below sea level too.

John

"John Larkin" wrote in
message ...
Wow. If it was delta, then 110 3-phase would require 6 wires (or five
if you cheat and share one corner) so the 110 3-phase motor would need
three isolated windings and most likely a 6-pole on/off switch. Was it
really like that?

Nope. Draw a picture of a Delta, center-tap each winding, and the three
center taps form another delta at half the voltage. Used a perfectly
standard (for 1922) 3 phase, 3 wire, 110v, 25Hz motor.

The 110 volt service made no connection to the corners of the 220 delta. The
110 delta was fed only from the center taps.