3 phase Delta / Star : Line or Phase?

In summary, when studying for an exam and trying to determine the difference between line current/voltage and phase current/voltage, it is important to understand the concept of "phase" and "line." To find phase current, one can divide the voltage by the impedance. This applies to both star and delta configurations, but for delta, phase current is equal to 1/√3 times the line current.
  • #1
Cocoleia
295
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Homework Statement


I am studying for an exam and I never know if I am finding line current / voltage or phase current / voltage. How can I tell? I guess I am confused on what "phase" and "line" represent. For example:
upload_2017-10-29_17-7-2.png

If I do the voltage divided by the impedance, then this gives me phase current, but how do I know?

Does it differ for star and delta configurations? If this example would have been in star would I still have found the phase current by doing that division ?
 

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  • #2
Cocoleia said:
If I do the voltage divided by the impedance, then this gives me phase current,
And for star, it is equal to line current. For delta, phase current is equal to 1/√3 times the line current.
 

1. What is a 3 phase Delta / Star connection?

A 3 phase Delta / Star connection is a type of electrical connection used in three-phase power systems. It consists of three phases (A, B, and C) connected in a triangular shape (Delta connection) and three neutral points connected in a star shape (Star connection).

2. What is the difference between line and phase voltages in a 3 phase Delta / Star connection?

In a 3 phase Delta / Star connection, line voltage refers to the voltage between any two of the three phases (A, B, and C), while phase voltage refers to the voltage between one phase (A, B, or C) and the neutral point.

3. How are line and phase currents related in a 3 phase Delta / Star connection?

In a 3 phase Delta / Star connection, line current is equal to the square root of 3 times the phase current. This means that the line current is higher than the phase current in this type of connection.

4. What are the advantages of using a 3 phase Delta / Star connection?

One advantage of a 3 phase Delta / Star connection is that it allows for higher power transmission compared to single phase connections. It also provides a more balanced load distribution and requires less wiring compared to other three-phase connections.

5. Are there any limitations or drawbacks to using a 3 phase Delta / Star connection?

One limitation of a 3 phase Delta / Star connection is that it requires a neutral wire, which can increase the cost of installation. It also cannot be used for motors that require a high starting torque. Additionally, the phase voltage in a Delta / Star connection is not as stable as in other three-phase connections, which may affect sensitive equipment.

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