Power distribution - Per unit question problem

In summary, per unit is a method of normalizing values in power distribution to a common base, allowing for easier comparison and analysis of different systems. It is calculated by dividing actual values by base values and is used due to its advantages of simplifying calculations, allowing for easy identification of errors, and convenient representation of quantities.
  • #1
JJ91
41
0
Hi,

exam question:
23vl0tg.jpg


My doubts start where it comes up with: S=75(0.8-j0.6) and Vr = 0.97 p.u.

Its easy to determine that 75 comes from 60/0.8, but where is the part in the brackets coming from ?

Also how was the 0.97 determined ?

Thanks in advance.
 
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  • #2
does not PF of 0.8 dictate a 3::4::5 triangle? (0.6::0.8::1.0) ? that's the bracketed part.

and 32/33 = .97?

remember it's per unit - everything a fraction of nominal.
 
  • #3
This must be way he did it, Thanks.
 

FAQ: Power distribution - Per unit question problem

1. What is the concept of per unit in power distribution?

The concept of per unit in power distribution is a method of normalizing values and quantities in a power system to a common base. This allows for easier comparison and analysis of different power systems regardless of their size or voltage levels.

2. How is per unit calculated in power distribution?

Per unit is calculated by dividing the actual value of a quantity by its corresponding base value. The base values are typically chosen as the rated values of the system, such as the rated voltage or power.

3. Why is per unit used in power distribution instead of absolute values?

Per unit is used in power distribution because it allows for easier analysis and comparison of different systems. Absolute values can vary greatly between systems, making it difficult to make meaningful comparisons. Per unit values, on the other hand, are normalized and therefore can be compared directly regardless of the system size or voltage levels.

4. How is per unit used in power system calculations?

Per unit is used in power system calculations by converting all values to their per unit values and performing the calculations. This allows for the simplification of equations and makes it easier to identify and correct any errors in the calculations.

5. What are the advantages of using per unit in power distribution?

The advantages of using per unit in power distribution include simplified calculations, easier comparison and analysis of different systems, and the ability to identify errors in calculations. It also allows for the convenient representation of quantities in a system, making it easier to understand and troubleshoot any issues that may arise.

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