Power factor in three phase system

  In our previous topic, we already know and had knowledge in getting power factor correction. Now in three phase system power factor is also applicable in correcting power consumer that is using this system.

using this example, you can easily get how to solve power factor correction.

Two balanced loads are connected to a 240-kV rms 60-Hz line, as

shown in Figure. Load 1 draws 30 kW at a power factor of 0.6

lagging, while load 2 draws 45 kVAR at a power factor of 0.8 lagging.

Assuming the abc sequence, determine: (a) the complex, real, and reactive

powers absorbed by the combined load, (b) the line currents, and

(c) the kVAR rating of the three capacitors -connected in parallel with

the load that will raise the power factor to 0.9 lagging and the capacitance

of each capacitor.

Power in Balanced system

SUMMARY of WYE and Delta connections formula

DELTA-WYE Connection

example,


A balanced Y-connected load with a phase impedance of is 40 + j 25 ohmssupplied by a balanced, positive sequence -connected source with a linevoltage of 210 V. Calculate the phase currents. Use 
Vab as reference.

Balanced DELTA-DELTA connection

WYE - DELTA connection

WYE-WYE connection

    EXAMPLE:

A Y-connected balanced three-phase generator with an impedance of 0.4+j 0.3 ohms per phase is connected to a Y-connected balanced load with an impedance of 24- + j19 ohms per phase. The line joining the generator and the load has an impedance of 0.6 + j0.7 ohms per phase. Assuming a positive sequence for the source voltages and that Van = 120 ∠ 30 °  V, find : (a) the line voltages, (b) the line currents.

Balanced Three-Phase Voltages