3 Phase Systems in a Wye Configuration

In summary: Therefore, it is important to have a balanced load for a balanced wye configuration. In summary, a balanced wye configuration will have a neutral potential of zero, and the line to line voltages will be sinusoidal. The currents may have different phases, but their sum will always be zero, unless the load is unbalanced. If a line is disconnected, there will be no neutral current, but the load may not function correctly. Thus, a balanced load is important for a balanced wye configuration.
  • #1
jendrix
122
4
Hello,

I have been going over the above topic and have a question about the neutral point of a balanced wye configuration. Would the line to line voltage remain constant? I am trying to picture two sine waves 120° apart and it's making me think the Va would be reducing as Vb was increasing at certain points? So would Vline still be alternating sinosoidally?

The reason I ask is I did an experiment in class where we had to set the line voltage to 10V and confirm it with a multimeter. Is it possible the multimeter was showing the peak value?

On another note, am I correct in thinking the voltage potential at the neutral point would be zero provided the system was balanced?

Thanks
 
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  • #2
You are correct in your thinking that, if the system is balanced, the neutral potential would be zero.

You are also correct in your thinking that, as one of the phase to neutral voltages changes, the other two will also change such that Va + Vb + Vc = 0. The line to line voltages would also be sinusoidal.
 
  • #3
magoo said:
You are correct in your thinking that, if the system is balanced, the neutral potential would be zero.

You are also correct in your thinking that, as one of the phase to neutral voltages changes, the other two will also change such that Va + Vb + Vc = 0. The line to line voltages would also be sinusoidal.

So that would mean the current Ia, Ib and Ic have a phase different with each other but at all times the sum of current at the neutral node would be 0?

Therefore in order for a system to be unbalanced the input voltage at A,B,C would either have to have a different peak or not be 120 degrees apart? Or have different loads?Thanks
 
  • #4
jendrix said:
So would Vline still be alternating sinosoidally?

Yes. The differential voltage between two phases is sinusoidal.

The line voltages will be symmetrical and separated by 120° about the neutral.

The current will be balanced if the load is balanced. The phase of the current will be determined by the impedance of the load.

If the load is not connected to the neutral then the neutral currents will cancel at the centre of the 'Y' and the neutral conductor will carry zero current.

See attached picture. It shows 3 phases, each 230Vpeak, NOT RMS.
It also shows one of the three, two phase differential line voltages, red – yellow.
3PH.png
 
  • #5
Baluncore said:
Yes. The differential voltage between two phases is sinusoidal.The current will be balanced if the load is balanced. The phase of the current will be determined by the impedance of the load.

If the load is not connected to the neutral then the neutral currents will cancel at the centre of the 'Y' and the neutral conductor will carry zero current.

View attachment 203303

If the load at for example A wasn't connected then wouldn't that cause the system to become unbalanced as the the impedance at A would be infinite as it would be an open circuit?
 
  • #6
jendrix said:
If the load at for example A wasn't connected then wouldn't that cause the system to become unbalanced as the the impedance at A would be infinite as it would be an open circuit?
Baluncore said:
The current will be balanced if the load is balanced.
If the load is unbalanced then the currents in the lines will be unbalanced.
If one line is disconnected, the total current flowing in the three lines will still sum to zero. There can be no neutral current.
The load may not function correctly if one phase is not connected.
 

1. What is a 3 phase system in a wye configuration?

A 3 phase system in a wye configuration is a type of electrical power distribution system that consists of three voltage sources connected in a triangular shape, with one end of each voltage source connected to a common point known as the neutral or "wye" point. This type of system is commonly used in industrial and commercial applications.

2. What are the advantages of using a 3 phase wye system?

One of the main advantages of a 3 phase wye system is that it allows for a more efficient distribution of power compared to a single phase system. The three voltage sources in a wye configuration can be connected in either a delta or a wye arrangement, which provides flexibility in power distribution and can help balance the load between phases. Additionally, a 3 phase wye system can handle higher power loads and is more reliable than a single phase system.

3. How is a 3 phase wye system different from a delta system?

In a delta system, the three voltage sources are connected in a triangular arrangement, with each voltage source connected to two others. This creates a closed loop, and there is no neutral point. In contrast, a 3 phase wye system has a neutral point and the voltage sources are connected in a Y-shaped arrangement. This allows for a more balanced distribution of power and provides a neutral connection point for single phase loads.

4. Can a 3 phase wye system be used in a residential setting?

While a 3 phase wye system is commonly used in industrial and commercial settings, it is not typically used in residential settings. This is because most residential homes do not require the high power demands that a 3 phase system can provide. Additionally, the cost of installing and maintaining a 3 phase system may not be practical for residential use.

5. How is power measured in a 3 phase wye system?

In a 3 phase wye system, power is measured in kilowatts (kW) and is calculated by multiplying the voltage by the current by the power factor. The power factor is a measure of how efficiently the system is using the power and is typically a decimal between 0 and 1. The total power in a 3 phase wye system is the sum of the power in each individual phase.

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