Question { Sterling, 75518 }

What is the rating of your capacitor bank at your company.

Answer

The correct method for PFC is to calculate how much correct you need.
If you know the PF and Pd of a motor being used on average, and want to improve to 90%p.f. then compute then angle of PF before and after from theta=cos^-1(PF) then take difference in tan (theta) * Pd

Good to Know:
Important formulas which is used for Power factor improvement calculation as well as used in the above calculation

Power in Watts
kW = kVA x Cosθ
kW = HP x 0.746 or (HP x 0.746) / Efficiency … (HP = Motor Power)
kW = √ ( kVA2– kVAR2)
kW = P = VI Cosθ … (Single Phase)
kW = P =√3x V x I Cosθ … (Three Phase)

Apparent Power in VA
kVA= √(kW2+ kVAR2)
kVA = kW/ Cosθ

Reactive Power in VA
kVAR= √(kVA2– kW2)
kVAR = C x (2 π f V2)

Power factor (from 0.1 to 1)
Power Factor = Cosθ = P / V I … (Single Phase)
Power Factor = Cosθ = P / (√3x V x I) … (Three Phase)
Power Factor = Cosθ = kW / kVA … (Both Single Phase & Three Phase)
Power Factor = Cosθ = R/Z … (Resistance / Impedance)

XC = 1/ (2 π f C) … (XC = Capacitive reactance)
IC = V/ XC … (I = V / R)

Required Capacity of Capacitor in Farads/Microfarads
C = kVAR / (2 π f V2) in microfarad

Required Capacity of Capacitor in kVAR
kVAR = C x (2 π f V2)