On Fri, 3 Mar 2017 14:24:22 -0600, Sam E
wrote:

On 03/03/2017 12:14 PM, #1 wrote:
On 03/03/2017 12:44 PM, Sam wrote:
The problem lies with the phases of electricity you are getting.
240v is two alternating phases of 120v. it is possible to wire a 240v
outlet
using 2 120v lines with opposite phases.

You'll need one of those magic transformers that turns a single-phase
input on the primary into a two-phase output on the secondary.


No transformer needed. TWO single-phase lines from the same source
(already 180 degrees out of phase, as needed here).

Now, maybe you can figure out how to get 3 phase.


If it is a dual voltage motor (which most medium sised compressor
motors are) you just need to switch the wires in the motor and change
the plug. HOWEVER the compressor will require twice the amperage at
half the voltage, so unless it is smaller than 2 real horsepower it
will NOT run on a 15 amp circuit, and will quite likely trip a 20 amp
on starting. (which is why I switched MINE from 120 to 240 volts)

There is no "phase issue" at all. There is no such thing as "two
phase" power, at least not in common North American use. All 120 volt
power in north american distribution systems is derived from center
tapped 240 volt single phase transformers except in a 3 phase
distribution system, where you get 120 and 208 (120 across 1 phase,
and 208 across 2 phases of the 3 phase supply).

On 3/3/17 4:28 PM, wrote:

There is no "phase issue" at all. There is no such thing as "two
phase" power, at least not in common North American use. All 120
volt power in north american distribution systems is derived from
center tapped 240 volt single phase transformers except in a 3 phase
distribution system, where you get 120 and 208 (120 across 1 phase,
and 208 across 2 phases of the 3 phase supply).

The REAs in rural Nebraska also supply three phase power to
irrigation well motors. I've seen center tap delta which is basically
double what you referenced. There is the Y configuration, 277 volts
each line to ground. Lastly is the corner ground delta. Two lines read
480 to
ground, the third line reads 0 to ground. All of those read 480 line
to line.
Some grain bin drying systems are wired with the three phase you
mentioned.
That lets the electricians use common 120 volt controls. There is also
enough
power with the three phase to run drying fans.

On Fri, 3 Mar 2017 18:37:52 -0600, Dean Hoffman
wrote:

On 3/3/17 4:28 PM, wrote:

There is no "phase issue" at all. There is no such thing as "two
phase" power, at least not in common North American use. All 120
volt power in north american distribution systems is derived from
center tapped 240 volt single phase transformers except in a 3 phase
distribution system, where you get 120 and 208 (120 across 1 phase,
and 208 across 2 phases of the 3 phase supply).

The REAs in rural Nebraska also supply three phase power to
irrigation well motors. I've seen center tap delta which is basically
double what you referenced. There is the Y configuration, 277 volts
each line to ground. Lastly is the corner ground delta. Two lines read
480 to
ground, the third line reads 0 to ground. All of those read 480 line
to line.
Some grain bin drying systems are wired with the three phase you
mentioned.
That lets the electricians use common 120 volt controls. There is also
enough
power with the three phase to run drying fans.
That is true - there are MANY other "industrial" voltages - and 3
phase Delta or wye .
However, in "residential" systems, except in some larger MURBs, it is
exclusively 120/240. In those MURBs, 120/208 3 phase..

All this "non-standard residential" has NOTHING to do with converting
a 240 volt compressor to 120 volts - because ALL 240 volt systems -
even in europe behave the same (with the exception it may be 50hz
instead of 60) and a motor connected for 220/240 will work on any 60hz
240 volt circuit. By reconfiguring for 120 volts it will require twice
the amperage. If, in the extremely unlikely case, the motor is 240
volts only and can not be reconfigured, the cheapest solution (and
simplest in most cases) is a replacement motor (assuming a belt driven
standard compressor - not too many 240 volt integrated oil-less
compressors on the north american market)
If this is a european market compressor brought to North America, all
bets are off.

On Fri, 3 Mar 2017 18:37:52 -0600, Dean Hoffman
wrote:

On 3/3/17 4:28 PM, wrote:

There is no "phase issue" at all. There is no such thing as "two
phase" power, at least not in common North American use. All 120
volt power in north american distribution systems is derived from
center tapped 240 volt single phase transformers except in a 3 phase
distribution system, where you get 120 and 208 (120 across 1 phase,
and 208 across 2 phases of the 3 phase supply).

The REAs in rural Nebraska also supply three phase power to
irrigation well motors. I've seen center tap delta which is basically
double what you referenced. There is the Y configuration, 277 volts
each line to ground. Lastly is the corner ground delta. Two lines read
480 to
ground, the third line reads 0 to ground. All of those read 480 line
to line.
Some grain bin drying systems are wired with the three phase you
mentioned.
That lets the electricians use common 120 volt controls. There is also
enough
power with the three phase to run drying fans.

I have also seen 240v 3p corner delta, usually feeding sewer lift
pumps. It is pretty strange the first time you see it because it is 3
phase with only 2 ungrounded conductors so it looks like single phase.
(2 black wires and a white on a 2 pole breaker)

On Sat, 04 Mar 2017 00:02:06 -0500, wrote:

On Fri, 3 Mar 2017 18:37:52 -0600, Dean Hoffman
wrote:

On 3/3/17 4:28 PM, wrote:

There is no "phase issue" at all. There is no such thing as "two
phase" power, at least not in common North American use. All 120
volt power in north american distribution systems is derived from
center tapped 240 volt single phase transformers except in a 3 phase
distribution system, where you get 120 and 208 (120 across 1 phase,
and 208 across 2 phases of the 3 phase supply).

The REAs in rural Nebraska also supply three phase power to
irrigation well motors. I've seen center tap delta which is basically
double what you referenced. There is the Y configuration, 277 volts
each line to ground. Lastly is the corner ground delta. Two lines read
480 to
ground, the third line reads 0 to ground. All of those read 480 line
to line.
Some grain bin drying systems are wired with the three phase you
mentioned.
That lets the electricians use common 120 volt controls. There is also
enough
power with the three phase to run drying fans.

I have also seen 240v 3p corner delta, usually feeding sewer lift
pumps. It is pretty strange the first time you see it because it is 3
phase with only 2 ungrounded conductors so it looks like single phase.
(2 black wires and a white on a 2 pole breaker)
With 3 phase motors? Requires 4 wires for a 3 phase motor on corner
delta. Sounds more like single phase 208. - because theree are
generally only 2 ungrounded wires in a corner delta (which is no
longer allowed, to the best of my knowlege, in Ontario) - and with
corner delta 3 phase you have no 120 without a transformer - and
generally no center-tapped transformer is used (which is generally why
grounded delta was used - to avoid the requirement for a more
expensive center tapped transformer) Means you can't use a 240 device
that has 120 volt controls without installing a "control transformer"
on each device.to supply the required 120 volts.

On Sat, 04 Mar 2017 01:18:19 -0500, wrote:

On Sat, 04 Mar 2017 00:02:06 -0500, wrote:

On Fri, 3 Mar 2017 18:37:52 -0600, Dean Hoffman
wrote:

On 3/3/17 4:28 PM, wrote:

There is no "phase issue" at all. There is no such thing as "two
phase" power, at least not in common North American use. All 120
volt power in north american distribution systems is derived from
center tapped 240 volt single phase transformers except in a 3 phase
distribution system, where you get 120 and 208 (120 across 1 phase,
and 208 across 2 phases of the 3 phase supply).

The REAs in rural Nebraska also supply three phase power to
irrigation well motors. I've seen center tap delta which is basically
double what you referenced. There is the Y configuration, 277 volts
each line to ground. Lastly is the corner ground delta. Two lines read
480 to
ground, the third line reads 0 to ground. All of those read 480 line
to line.
Some grain bin drying systems are wired with the three phase you
mentioned.
That lets the electricians use common 120 volt controls. There is also
enough
power with the three phase to run drying fans.

I have also seen 240v 3p corner delta, usually feeding sewer lift
pumps. It is pretty strange the first time you see it because it is 3
phase with only 2 ungrounded conductors so it looks like single phase.
(2 black wires and a white on a 2 pole breaker)

With 3 phase motors? Requires 4 wires for a 3 phase motor on corner
delta. Sounds more like single phase 208. - because theree are
generally only 2 ungrounded wires in a corner delta (which is no
longer allowed, to the best of my knowlege, in Ontario) - and with
corner delta 3 phase you have no 120 without a transformer - and
generally no center-tapped transformer is used (which is generally why
grounded delta was used - to avoid the requirement for a more
expensive center tapped transformer) Means you can't use a 240 device
that has 120 volt controls without installing a "control transformer"
on each device.to supply the required 120 volts.

They used corner delta because the only load is the motor and a 240v
MCC. There is no 120 available and it is not needed. The 4 wires are 2
hots, one neutral (another phase) and the grounding conductor. It
looks visually exactly like 120/240 single phase except that the
"neutral" is actually tied to the 3d phase, not the center tap of a
transformer. In fact they did it with just 2 transformers similar to
the way they do center tapped delta vee. (red leg delta)
The advantage of corner delta to the installer is they can use cheaper
2 pole switch gear. The only added requirement is everything needs to
be 240v rated (delta rated breakers)