Why dont we use 2 phase DC?

[Direct.Dude]

I'm not sure if I invented the word or the form, but why dont we use it already. 2 phase dc is basically something with 1 positive and 2 negative and has 2 phases (of course), 1 phase from negative 1 to positive and another from negative 2 to positive, which it switches quickly, preferrably at 60hz. It can easily be transformed with transformers and changed to true DC by connecting the two negatives together. Also unlike AC it is always in its true potential. If someone already invented it, can I know the name?

Thanks!

-The Direct Dude

[studiot]

1)

I'm not sure if I invented the word or the form, but why dont we use it already. 2 phase dc is basically something with 1 positive and 2 negative and has 2 phases (of course), 1 phase from negative 1 to positive and another from negative 2 to positive, which it switches quickly, preferrably at 60hz.

 

2)

It can easily be transformed with transformers and changed to true DC by connecting the two negatives together. Also unlike AC it is always in its true potential. If someone already invented it, can I know the name?

Thanks!

-The Direct Dude

 

 

 

I have separated your post into two parts.

 

Part (1), The description of your proposal.

 

This is properly called two level or bi level direct current or unidirectional current.

Some might also call it a biased square wave.

It does not have two phases.

 

Part (2) Your support reasons and proposed advantages.

 

 

Such a system is extremely inefficienct for power transfer, but is used for signal purposes (hence the square wave terminology)

Transformers to handle square waves are quite diffeently constructed from those for sine waves.

The radiated interference signal from sine wave power sources is bad enough, but square waves would be sunstantially worse.

[kisai]

Off the top of my head:

 

1) Power losses. It is very inefficient to transfer electricity at low voltages. Edison's original plans for providing DC current for the city of New York would have required generators every mile or so. The further you lived from the generator, the greater your losses. and the less voltage to your house. This originally would have been too terrible a problem, given that the only loads for homes in those days were primarily electric and a few motors, but it would be a difficult problem today with computers, which really don't like unstable sources.

 

2) DC cannot be stepped up and down like AC can using transformers, so you cannot transfer power at high voltages, then transfer it to homes directly without wasting a great deal of it,

Edited January 21, 2016 by kisai

[studiot]

Off the top of my head:

 

1) Power losses. It is very inefficient to transfer electricity at low voltages. Edison's original plans for providing DC current for the city of New York would have required generators every mile or so. The further you lived from the generator, the greater your losses. and the less voltage to your house. This originally would have been too terrible a problem, given that the only loads for homes in those days were primarily electric and a few motors, but it would be a difficult problem today with computers, which really don't like unstable sources.

 

2) DC cannot be stepped up and down like AC can using transformers, so you cannot transfer power at high voltages, then transfer it to homes directly without wasting a great deal of it,

 

Look carefully at the OP proposal.

It will work with a (suitable) transformer.

It will not be subject to greater resistive transmission losses than other systems: That is not its problem.

 

What the OP is describing looks something like this.

 

Edited January 21, 2016 by studiot

[Direct.Dude]

I dont think you understand it, I've searched biased square wave and it isnt quite the same. Also I dont see why it wouldn't have 2 phases. What I mean is that the voltage is constanly switching from 1 phase to another. suppose like this

Phase 1:

--

- |

+|

Phase 2:

-

--|

+|

 

And I forgot to mention it can also be easily converted to AC by using a transformer with 2 primary one in clockwise and other in counterclockwise.

[studiot]

If you mean something different from what I drew, please post a proper diagram to show what you do mean.

 

I cannot make anything new out of your post 5

 

(ask for help achieving this if you need it)

[Externet]

Most consumer and professional electronic equipment already works with dual (+)15V , (-)15V rails, and ground DC supply. The operational amplifiers in circuits mostly are made to use both 'phases'. Even computing equipment uses ±5V, ± 12V.

If that is what you meant.

[John Cuthber]

I'm not sure if I invented the word or the form, but why dont we use it already. 2 phase dc is basically something with 1 positive and 2 negative and has 2 phases (of course), 1 phase from negative 1 to positive and another from negative 2 to positive, which it switches quickly, preferrably at 60hz. It can easily be transformed with transformers and changed to true DC by connecting the two negatives together. Also unlike AC it is always in its true potential. If someone already invented it, can I know the name?

Thanks!

-The Direct Dude

Why bother?

[Direct.Dude]

"Why bother?"

I am a big fan of DC, thats why

"Please draw a proper diagram to show what you mean"

[EdEarl]

"Why bother?"

I am a big fan of DC, thats why

"Please draw a proper diagram to show what you mean"

DC is defined as a two wire system with one plus and one minus. Your diagram shows the voltage changing from plus to minus and minus to plus, which means it is an AC system, except a square wave instead of a sine wave. Square waves are very inefficient when put through a transformer, with output no longer being a true square wave and the transformer heat up as a result.

[studiot]

EdEarl

 

DC is defined as a two wire system.

 

Good morning Ed,

Where is DC defined as a two wire system?

See Externet's comments, post#7

Further a supply is only alternating if it changes polarity.

The point is that the OP specified 'switching' between two negative supplies. Each negative supply must have a reference.return wire so that makes 3 or 4 wires.

Since there is no polarity change, it is simply DC pulsed from one level to another.

 

Thank you direct dude, for your diagrams.

They do not indicate polarity or wiring so I am still left guessing.

If you combine the two supplies to form a two wire system then you will end up with zero if the two supplies have the same voltage.

[EdEarl]

Where is DC defined as a two wire system?

See Externet's comments, post#7

Further a supply is only alternating if it changes polarity.

The point is that the OP specified 'switching' between two negative supplies. Each negative supply must have a reference.return wire so that makes 3 or 4 wires.

Since there is no polarity change, it is simply DC pulsed from one level to another.

 

 

Good morning Ed,

Where is DC defined as a two wire system?

 

Thank you direct dude, for your diagrams.

They do not indicate polarity or wiring so I am still left guessing.

If you combine the two supplies to form a two wire system then you will end up with zero if the two supplies have the same voltage.

OK, it is literally defined as a "Direct current (DC) is the unidirectional flow of electric charge." (Wikipedia)

To achieve such a flow one needs an EMF source, such as a battery, with a + and - end, which one can connect with a single wire to each end and cause a short circuit. Otherwise, you must have two wires to connect to a load, such as a light bulb or motor. That different sources, e.g., +15, -15, +6, etc., can share a common ground doesn't change the fact that each source has a + and -; the flow of each one requires two wires to connect to a load.

 

Direct.Dude's diagram showed a square wave, unlabeled, with words that said one phase changes from negative to positive (AC because current direction changes as EMF changes from negative to positive), and second square wave changing from positive to negative (also AC).

 

If the square waves did not change polarity, the Fourier analysis of the wave form would be a DC EMF plus various AC harmonics added to the DC. Thus, while the definition of DC allows varying DC, such signals are a combination of AC harmonics and a constant DC EMF. This analysis is necessary to understand how transformers affect 60Hz square waves, according to the OP, quoted below. IIRC transformers work best for one frequency of sine wave, and less well for other frequencies. Since a square wave contains many frequencies, it is distorted by a transformer, which means energy is lost heating the transformer.

 

I'm not sure if I invented the word or the form, but why dont we use it already. 2 phase dc is basically something with 1 positive and 2 negative and has 2 phases (of course), 1 phase from negative 1 to positive and another from negative 2 to positive, which it switches quickly, preferrably at 60hz. It can easily be transformed with transformers and changed to true DC by connecting the two negatives together. Also unlike AC it is always in its true potential. If someone already invented it, can I know the name?

Thanks!

-The Direct Dude

[studiot]

Thank you for your reply, Ed.

 

I agree with much of what you say, but I think things are a tad more subtle and complicated than that. We can discuss the meaning of DC v AC in another thread after we have determined what the OP actually means. I think that the difference between DC and AC is off topic here.

I am not sure the OP himself is quite clear about his idea since post#1 contains some contradictions and as both you and I have pointed out the subsequent diagram is not complete.

My objective is to get directdude to think further about his idea and try to lead him to make his own discovery about the implications of what he is proposing.

 

I am holding my discussion of transformers until after the proposed circuit details are cleared up.

 

I hope the snow has not reached you neck of the woods.

[EdEarl]

Snow! It hasn't snowed here since IIRC 1985. It's a nice spring day here, except its January. I'll let you work with direct.dude; I'm impatient.

[studiot]

Spring here too, so it's raining.

 

 

Directdude, let's here from you.

[Direct.Dude]

There hasn't been snow in my country for years

Being on topic, it has 3 wires. When that wave (in my diagram) is at its peak, its at the rated voltage which is more than 0. When its at its lowest, its at 0. If you connect positive to a negative and show it on top and positive to the other negative and show it on the bottom, that will be the result. So if it is a 24VDC 2 phase, it will be 24 at its peak and 0 at its lowest. From positive to negative, it will never be less than 0, so it isn't AC.

Edited January 26, 2016 by Direct.Dude

[Strange]

So why not use two wires with one at 0 and one at 24V?

 

What is the benefit of the extra wire and extra circuitry to switch voltages on the wires? It will also generate more interference than normal AC. It will require extra circuitry at the other end to either convert it to a single 24V DC level or to AC.

 

I am not seeing any advantages to this.

[Direct.Dude]

Wrong, it is ​easier ​to convert it into good old DC/AC, like I said above, having a transformer with a primary that has negatives connected at the ends and positive at the middle will convert it to AC and connecting the 2 negatives will convert it to single phase DC

This is just one of the advantage.

The other advantage is as it is DC, it cannot go through the human body by exploiting capacitance, making it much safer - plus even that dc voltage will be applied half the time unless you hold both negatives together.

2 wires with one at 0 and other at 24 is just plain dc, you cant convert it to ac without complicated circuitry or mechanical inverters and you cant run it directly through a transformer.

[studiot]

OK dude, I now understand your system and I agree it could physically work.

 

One immediate disadvantage I can see is that it requires three wires to distribute it, rather than the traditional two.

 

A second disadvantage would be the increased complexity of the wiring of appliances to operate on such a supply.

 

Please explain the distribution of such a system ie where it would be generated, at what voltage and how it would arrive at the consumer?

Would the system be distributed from the power station as DC or would it be AC and converted somewhere down the line?

 

Finally I think this proposition is a fine candidate for proper use of the speculations forum.

It is, after all, a speculation, though based one real physics rather than guesswork which is why I say proper use.

[Direct.Dude]

OK dude, I now understand your system and I agree it could physically work.

 

One immediate disadvantage I can see is that it requires three wires to distribute it, rather than the traditional two.

 

A second disadvantage would be the increased complexity of the wiring of appliances to operate on such a supply.

 

Please explain the distribution of such a system ie where it would be generated, at what voltage and how it would arrive at the consumer?

Would the system be distributed from the power station as DC or would it be AC and converted somewhere down the line?

 

Finally I think this proposition is a fine candidate for proper use of the speculations forum.

It is, after all, a speculation, though based one real physics rather than guesswork which is why I say proper use.

 

It sure does, although how many overhead power lines do you see with 2 wires?

I don't think that really is a disadvantage as the appliances can run off DC and you can connect the negatives together after a diode. It can easily be generated by using one magnet with only one pole at a side (the other pole exists but is "invisible" to the wires) with one coil at the top and one at the bottom, their positives connected together.

It can come at any voltage but I think it would be better if it arrives at either 24 volts so normal DC appliances can work easily or at 120, 170, 240 or 370 volts, the current AC volts in use and their corresponding peaks.

Thanks for replying

Edited January 28, 2016 by Direct.Dude

[Phi for All]

Finally I think this proposition is a fine candidate for proper use of the speculations forum.

It is, after all, a speculation, though based one real physics rather than guesswork which is why I say proper use.

 

!

Moderator Note

Let's do this.

 

Moved to Speculations, please read the special rules for that section. Assertive claims should be backed up by evidence. Enjoy!

[Direct.Dude]

I forgot one thing for converting it to DC!

If you just connect the negatives together it will connect them at all instances, so you either need to generate a new instance using a 1:1 transformer or use diodes on the negatives to prevent interference with devices that need 2 phase instead of 1 phase.

[studiot]

 

It can come at any voltage but I think it would be better if it arrives at either 24 volts so normal DC appliances can work easily or at 120, 170, 240 or 370 volts, the current AC volts in use and their corresponding peaks.

 

 

This statement needs amplification.

 

Further I cannot agree with you about safety.

 

One characteristic of DC is that a victim who has grasped a live conductor cannot let go.

 

This is not true at AC.

[Mordred]

 

 

This statement needs amplification.

 

Further I cannot agree with you about safety.

 

One characteristic of DC is that a victim who has grasped a live conductor cannot let go.

 

This is not true at AC.

I definitely agree with this statement. I find 24 Vdc far more dangerous than 120 ac.

[Direct.Dude]

Yes, I am aware of that. However, that is only if the DC passes through him. AC can pass easily due to the capacitance of the human body but DC can't. 340 volts DC hurts much less than 120 volts AC. If you take a bug zapper and touch the inner net and the outer net, you will find out how much 170VDC hurts. And don't even think about doing that with 120VAC.

Edited January 29, 2016 by Direct.Dude