Power in Parallel R-C-L Circuits:
Example: An100 ? XL, 800 ? resistance, and an 80 ? XC are in parallel along with a 120V, 60Hz source, as display in Figure.
Find:
1. IT
2. pf
3. P
4. Q
5. S
Figure: Parallel R-C-L Circuit
Solution:
1.
2. pf = cosθ θ = arctan(IC - IL/ IR)
=cos(arctan(IC - IL/ IR)
= cos(arctan(1.5 - 1.2/ 0.15)
= cos(arctan(2))
= cos(63.4º)
pf =0.45
3. P = EIcosθ
= (120)(0.34)(0.45)
P = 18.36 watts
4. Q = EIsin θ
= (120)(0.34)(0.89)
Q = 36.4 VAR
5. S= EI
= (120)(0.34)
S = 40.8 VA