Three-Phase Delta Network: Not all Voltage Sources are 120V?

In summary, the conversation discusses the use of the Delta Network from an image provided. It is stated that between Y-X, Y-Z, and X-Z, there should be 120V. However, if values are assigned to make these statements true, inconsistencies arise. This is because the voltages are not DC, but rather sine functions that add up in a manner similar to vectors. By using phasor notation and understanding 3 phase voltage, these inconsistencies can be resolved.
  • #1
yosimba2000
206
9
Using the Delta Netowrk from this image: http://www.belden.com/images/B23_WyevsDelta.jpg

Between Y-X, there should be 120V.
Between Y-Z, there should be 120V.
Between X-Z, there should be 120V.

But wait!

If we assign values to make the above statements true...

Call X = 0V, and Y = 120V, so from Y-X is 120V.
If Y-Z should be 120V, and Y is already 120V, then Z should be 240V. This is so from Y-Z is 120V.
If X-Z should be 120V, and Z is 240V, then X should be 360V.

But that can't be, since we already said X is 0V to make Y-X = 120V. From what I know, if X is held to be 0V and Z is 240V, then from Z-X is 240V!
If X is made to be 360V, then Y-Z is no longer 120V!


What am I doing wrong?
 
Engineering news on Phys.org
  • #2
120V will be the rms value of voltage and not the instantaneous value. Instantaneous values will be different at each instant.
 
  • #3
yosimba2000 said:
What am I doing wrong?

You're treating them as if they were DC voltages.

They are really sine functions, 120√2sin(377t+Φ) where Φ is 0 or ±120 degrees

they add in a manner similar to vectors.

Look up phasor notation 3 phase voltage
http://www.electronics-tutorials.ws/accircuits/phasors.html
http://ece.k-state.edu/~starret/581/3phase.html
 
  • Like
Likes CalcNerd

FAQ: Three-Phase Delta Network: Not all Voltage Sources are 120V?

1. What is a three-phase delta network?

A three-phase delta network is a type of electrical circuit that consists of three voltage sources connected in a triangular formation. It is commonly used in industrial settings to power three-phase motors and other heavy-duty equipment.

2. How does a three-phase delta network differ from a typical single-phase circuit?

In a single-phase circuit, there is only one voltage source and the voltage between the source and neutral is 120V. In a three-phase delta network, there are three voltage sources and the voltage between any two sources is 120V, but the voltage between any one source and neutral is higher (usually 208V or 240V).

3. Why are not all voltage sources in a three-phase delta network 120V?

The voltage between any two voltage sources in a three-phase delta network is 120V, but the voltage between any one source and neutral is higher because the sources are connected in a triangular formation. This allows for more efficient distribution of power and is better suited for industrial applications.

4. How is power distributed in a three-phase delta network?

In a three-phase delta network, power is distributed evenly among the three voltage sources. Each source carries one-third of the total power load, resulting in a more balanced distribution of power compared to a single-phase circuit.

5. Can a three-phase delta network be converted to a single-phase circuit?

Yes, a three-phase delta network can be converted to a single-phase circuit by connecting the three voltage sources in a different configuration. However, this would result in a less efficient distribution of power and is not typically done in industrial settings.

Back
Top