Positive SSL
1 某工廠有一臺220V、60Hz、5馬力之單相感應電動機,其滿載功率因數為0.8滯後,並聯153.4μF電力電容器改善功率因數,改善後功率因數為多少? 100 統測
A 0.94
B 0.96
C 0.98
D 1

改善前:

cosθ1=0.8

tanθ1=0.75

Qc = 2πfCV2 = P (tanθ1-tanθ2)

Qc = 2π×60×153.4μ×2202=2797.5VAR

2797.5 = 5× 746 × (0.75- tanθ2)

tanθ2 = 0

改善後:

cosθ2=1