The bus in Example 16.5 supplies a 200-kVA, 480-V power electronics load that has the harmonic spectrum shown in Table E5.1 below, which also shows the harmonic impedances behind the bus. Determine 

(1) The rss and THD of the source current without the 600-kVAR capacitor bank and 

(2) The rss and THD of the bus voltage with a 600-kVAR capacitor connected to the bus.

Data from example 16.5'

A 480-V bus in an industrial plant supplying power to several feeders has a Thevenin source impedance behind the bus equal to 0.003 + j0.015 Ω/phase. A power factor correction capacitor rated 600 kVAR_3ph is connected to the bus as shown in the figure below. Determine the parallel resonance frequency and identify the precaution needed for connecting a power electronics load to this bus.

Table E5.1

Transcribed Image Text:

Bus Impedances and Voltage Drops at Bus due to Harmonic Currents Line current In (A) Harmonic Frequency Order (Hz) 5 7 11 13 300 420 660 780 50 30 15 7 Volt Drop/ Rh (2/ph) X₁ (22/ph) Z₁ (22/ph) ph V₁= ln Zh 0.003 0.003 0.003 0.003 0.075 0.105 0.165 0.195 0.0751 0.105 0.165 0.195 3.76 3.15 2.48 1.37