ACM3P 3-Phase AC Ammeters

Winfield Hill <winfieldhill@yahoo.com> wrote in
news:r7s6s501hti@drn.newsguy.com:

DecadentLinuxUserNumeroUno@decadence.org wrote...

We get our 240 VAC from a pole transformer (or ground) off ONE
phase of a three pase HV distribution system. From that ONE
phase, there is a center tapped transformer which is 180 degrees
out of phase with each other, so each could be referred to as a
phase, but only within the US residential feed setting. So we get
the full single phase 240 volt feed from the pole, but we ALSO get
the center tap from that secondary, so that within the house, we
can distribute 120 VAC branches, which are 'safer' from a human
shock death risk potential view. We feed the full 240 V to large
consumption items like electric dryers and our kitchen range.

So what gets 'supplied' is a center tapped supply of a
tranformer
secondary of 240 VAC, which is essentially two 120 VAC feeds into
the home. One of the main features of this system is faulty
return handling, and at the pole, lightning strike management, as
a hit on an ungrounded floating feed could end up sraying
lightning right inside your now ablaze home.

We're supposed to have the center-tap neutral
wire solidly connected to a water-pipe ground
or similar. I've observed that for many older
installations, the two sides of the 240V come
in as two insulated wires, but the center tap
is connected to a steel cable supporting the
pole-to-house wiring. This saves adding a
third electrical wire. But the cable-clamp
connection is a weak spot, that can become
corroded and fail.

Yeah. Ours in 1970 circa cincinnati area was to an 8 ft ground rod
right at the external entry point, and in the inside breaker box, I
guess because PVC plumbing was coming into being at the time. I
think there was a jumber from the breaker box over to the incoming
water pipe though, now that I think about it. So... both.

 

[Lasse Langwadt Christense]

torsdag den 23. april 2020 kl. 14.57.09 UTC+2 skrev John S:

On 4/20/2020 5:29 PM, Ricky C wrote:
On Monday, April 20, 2020 at 3:06:54 PM UTC-4, John S wrote:
On 4/19/2020 9:09 AM, Lasse Langwadt Christensen wrote:
søndag den 19. april 2020 kl. 15.28.11 UTC+2 skrev John S:
On 4/18/2020 7:32 PM, Ricky C wrote:
On Saturday, April 18, 2020 at 8:01:48 PM UTC-4, Lasse Langwadt Christensen wrote:
søndag den 19. april 2020 kl. 00.54.43 UTC+2 skrev Ricky C:
On Saturday, April 18, 2020 at 5:34:19 PM UTC-4, Lasse Langwadt Christensen wrote:
lørdag den 18. april 2020 kl. 23.12.05 UTC+2 skrev Winfield Hill:
Can a Murata / Datel ACM3P 3-Phase AC Ammeter,
complete with three current transformers, for $72,
be used with, e.g., a common single-phase 120-120
/ split 240 Vct household wiring, having both
balanced and unbalanced loads? A push-button
selects the "phase" you want to display. What
do they mean when they say 2-Phase AC current.


maybe they just wrongly call split-phase 2-phase ?
Though in some places each house get two out of three phases,
which from the meters point of view would be the same as three phase
with no load on one of the phases

unless there is some timing that rely on 120degree I don't see why it
wouldn't work on split phase

Win is in the US and we use 120 volts as our commodity power for household appliances. You can't use two taps of the three phase power for that unless using a particular type of delta transformer that center taps a coil. But then it's still 240 volt split phase.

The point is each side of the 240 volt circuit must be 120 volts from neutral/ground because that's what we use for a return. True three phase doesn't need a neutral for power purposes.


you can use two taps of the three phase power, it'll be 120V phase to neutral and 208V from phase to phase

Yep and that's not what we use here. It has to be 240 volts from phase to phase so we can run our ovens an furnaces.

I suppose we could run them from 208 volts, but we don't because we have 240 volt split phase handy. If we did use 208 volts everything would provide 25% less power.

I see that when charging my car on level 2 chargers a lot. They are at commercial sites where they have 3 phase and they just give 208 volts to the connection rather than bother with 240 resulting in slower charge times.


I have three-phase like everyone else here, it would be rather inconvenient with out a neutral, having to run everything on 400V

I'm talking about here where we use three phase as three phase, not as a distribution that you can pick lines off of for low voltage in the home. We have three phase on the power distribution, it's not very often brought down the street and hardly ever brought to a home. Pretty much commercial only.


What is split phase? Is that simply a single phase primary and
center-tapped secondary?

yes, https://en.wikipedia.org/wiki/Split-phase_electric_power


The term split phase is not familiar to me. Thank you.

It's not familiar to most people in the US either. They want to call it two phase.


Too bad. AFAIK, there is no two phase power commercially supplied in the US.

it would be a poor use of copper/aluminium. to distribute two-phase you need three wires with balanced load the current in the neutral is bigger than the phases

to distribute three-phase you need also three(four) wires, with a balanced load there is no current in the neutral

 

[Lasse Langwadt Christense]

torsdag den 23. april 2020 kl. 15.10.49 UTC+2 skrev DecadentLinux...@decadence.org:

John S <Sophi.2@invalid.org> wrote in
news:r7s3b0$ukd$6@dont-email.me:

On 4/20/2020 5:29 PM, Ricky C wrote:
On Monday, April 20, 2020 at 3:06:54 PM UTC-4, John S wrote:
On 4/19/2020 9:09 AM, Lasse Langwadt Christensen wrote:
søndag den 19. april 2020 kl. 15.28.11 UTC+2 skrev John S:
On 4/18/2020 7:32 PM, Ricky C wrote:
On Saturday, April 18, 2020 at 8:01:48 PM UTC-4, Lasse
Langwadt Christensen wrote:
søndag den 19. april 2020 kl. 00.54.43 UTC+2 skrev Ricky C:
On Saturday, April 18, 2020 at 5:34:19 PM UTC-4, Lasse
Langwadt Christensen wrote:
lørdag den 18. april 2020 kl. 23.12.05 UTC+2 skrev
Winfield Hill:
Can a Murata / Datel ACM3P 3-Phase AC Ammeter,
complete with three current transformers, for $72,
be used with, e.g., a common single-phase 120-120
/ split 240 Vct household wiring, having both
balanced and unbalanced loads? A push-button
selects the "phase" you want to display. What
do they mean when they say 2-Phase AC current.


maybe they just wrongly call split-phase 2-phase ?
Though in some places each house get two out of three
phases, which from the meters point of view would be the
same as three phase with no load on one of the phases

unless there is some timing that rely on 120degree I don't
see why it wouldn't work on split phase

Win is in the US and we use 120 volts as our commodity
power for household appliances. You can't use two taps of
the three phase power for that unless using a particular
type of delta transformer that center taps a coil. But
then it's still 240 volt split phase.

The point is each side of the 240 volt circuit must be 120
volts from neutral/ground because that's what we use for a
return. True three phase doesn't need a neutral for power
purposes.


you can use two taps of the three phase power, it'll be 120V
phase to neutral and 208V from phase to phase

Yep and that's not what we use here. It has to be 240 volts
from phase to phase so we can run our ovens an furnaces.

I suppose we could run them from 208 volts, but we don't
because we have 240 volt split phase handy. If we did use
208 volts everything would provide 25% less power.

I see that when charging my car on level 2 chargers a lot.
They are at commercial sites where they have 3 phase and they
just give 208 volts to the connection rather than bother with
240 resulting in slower charge times.


I have three-phase like everyone else here, it would be
rather inconvenient with out a neutral, having to run
everything on 400V

I'm talking about here where we use three phase as three
phase, not as a distribution that you can pick lines off of
for low voltage in the home. We have three phase on the
power distribution, it's not very often brought down the
street and hardly ever brought to a home. Pretty much
commercial only.


What is split phase? Is that simply a single phase primary and
center-tapped secondary?

yes, https://en.wikipedia.org/wiki/Split-phase_electric_power


The term split phase is not familiar to me. Thank you.

It's not familiar to most people in the US either. They want to
call it two phase.


Too bad. AFAIK, there is no two phase power commercially supplied
in the US.

We get our 240 VAC from a pole transformer (or ground) off ONE
phase of a three pase HV distribution system. From that ONE phase,
there is a center tapped transformer which is 180 degrees out of
phase with each other, so each could be referred to as a phase, but
only within the US residential feed setting.

but since it isn't different and larger than -180deg or smaller than +180deg
it is not really a more than one phase, you cannot add/subtract them to get additional phases

 

Lasse Langwadt Christensen <langwadt@fonz.dk> wrote in
news:450cd0ed-a0aa-42b3-bb08-bc474c577b18@googlegroups.com:

torsdag den 23. april 2020 kl. 15.10.49 UTC+2 skrev
DecadentLinux...@decadence.org:
John S <Sophi.2@invalid.org> wrote in
news:r7s3b0$ukd$6@dont-email.me:

On 4/20/2020 5:29 PM, Ricky C wrote:
On Monday, April 20, 2020 at 3:06:54 PM UTC-4, John S wrote:
On 4/19/2020 9:09 AM, Lasse Langwadt Christensen wrote:
søndag den 19. april 2020 kl. 15.28.11 UTC+2 skrev John S:
On 4/18/2020 7:32 PM, Ricky C wrote:
On Saturday, April 18, 2020 at 8:01:48 PM UTC-4, Lasse
Langwadt Christensen wrote:
søndag den 19. april 2020 kl. 00.54.43 UTC+2 skrev Ricky
C:
On Saturday, April 18, 2020 at 5:34:19 PM UTC-4, Lasse
Langwadt Christensen wrote:
lørdag den 18. april 2020 kl. 23.12.05 UTC+2 skrev
Winfield Hill:
Can a Murata / Datel ACM3P 3-Phase AC Ammeter,
complete with three current transformers, for $72,
be used with, e.g., a common single-phase 120-120
/ split 240 Vct household wiring, having both
balanced and unbalanced loads? A push-button
selects the "phase" you want to display. What
do they mean when they say 2-Phase AC current.


maybe they just wrongly call split-phase 2-phase ?
Though in some places each house get two out of three
phases, which from the meters point of view would be
the same as three phase with no load on one of the
phases

unless there is some timing that rely on 120degree I
don't see why it wouldn't work on split phase

Win is in the US and we use 120 volts as our commodity
power for household appliances. You can't use two taps
of the three phase power for that unless using a
particular type of delta transformer that center taps a
coil. But then it's still 240 volt split phase.

The point is each side of the 240 volt circuit must be
120 volts from neutral/ground because that's what we use
for a return. True three phase doesn't need a neutral
for power purposes.


you can use two taps of the three phase power, it'll be
120V phase to neutral and 208V from phase to phase

Yep and that's not what we use here. It has to be 240
volts from phase to phase so we can run our ovens an
furnaces.

I suppose we could run them from 208 volts, but we don't
because we have 240 volt split phase handy. If we did use
208 volts everything would provide 25% less power.

I see that when charging my car on level 2 chargers a lot.
They are at commercial sites where they have 3 phase and
they just give 208 volts to the connection rather than
bother with 240 resulting in slower charge times.


I have three-phase like everyone else here, it would be
rather inconvenient with out a neutral, having to run
everything on 400V

I'm talking about here where we use three phase as three
phase, not as a distribution that you can pick lines off
of for low voltage in the home. We have three phase on
the power distribution, it's not very often brought down
the street and hardly ever brought to a home. Pretty much
commercial only.


What is split phase? Is that simply a single phase primary
and center-tapped secondary?

yes,
https://en.wikipedia.org/wiki/Split-phase_electric_power


The term split phase is not familiar to me. Thank you.

It's not familiar to most people in the US either. They want
to call it two phase.


Too bad. AFAIK, there is no two phase power commercially
supplied in the US.

We get our 240 VAC from a pole transformer (or ground) off ONE
phase of a three pase HV distribution system. From that ONE
phase, there is a center tapped transformer which is 180 degrees
out of phase with each other, so each could be referred to as a
phase, but only within the US residential feed setting.

but since it isn't different and larger than -180deg or smaller
than +180deg it is not really a more than one phase, you cannot
add/subtract them to get additional phases


Correct.