Documents

8 24 2017 Per Unit Calculation(Student Version)

Description
lecture distribution
Categories
Published
of 17
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Transcript
  Per Unit Quantity ã The per unit quantity of voltage, current, power and impedance is found from dividing the actual quantity by a base value of that quantity.  −  =     ã Per unit value is denoted by ‘ p.u .’. ã The base value quantity typically follows transformer rating. ã The per unit values are the same irrespective of the sides of the transformer.  Base Value Selection (Single-phase circuit) ã Base values are real numbers , denote by subscript ‘ B ’. ã Voltage base values follow transformer voltage ratings. (   ) ã Only single base complex power in the system. ã Thus, the base values of real power, reactive power, and complex power are all the same real number.  1 =  1 =  1 ã Current base values are calculated from the base power and base voltage.    = 1   ã Impedance base values (same value for impedance, resistance, or reactance) are calculated from voltage and current.    =    =   1  Example ã A single-phase 20kVA, 480/120 V, 60 Hz transformer has an equivalent leakage impedance referred to 120-volt winding of    = 0.0525∠20 Ω. Using the transformer rating as base values, find per-unit leakage impedance.
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks