Power Factor Correction

Power Factor Correction is the process of improving the power factor of an electrical system—typically by reducing the phase difference between voltage and current—so that power is used more efficiently. Power factor is the ratio of real power (used to do work, measured in kW) to apparent power (total power supplied, measured in kVA).

PFC is needed when the power factor of a system is significantly less than 1 (typically below 0.95). This often occurs in facilities with lots of inductive loads like motors, pumps, HVAC systems, or fluorescent lighting. Low power factor results in:

• Higher energy costs due to utility penalties.
• Increased electrical losses.
• Overloaded equipment or reduced system capacity.

• Reduces electricity bills (especially demand charges)
• Frees up capacity on the electrical system, particularly in transformers & cables
• Improves efficiency by reducing losses in cables and transformers
• Enhanced equipment lifespan: Less strain on electrical components.
• Improves voltage regulation
• Helps meet utility compliance for power factor thresholds

PFC works by adding capacitors to the electrical system. These capacitors supply reactive power (kVAr) to counteract the inductive effects of certain loads, thus improving the overall power factor.

Understanding the difference between plain and detuned Power Factor Correction is crucial for safe and effective power quality management, especially in environments with harmonic-rich loads.

• Plain PFC involves connecting capacitor banks directly to the power system to supply reactive power and improve power factor.
• Use Case: Suitable for clean power environments with minimal harmonic distortion. Typically used in small-to-medium systems with linear loads (motors, HVAC, etc.).
• Risks: Resonance risk when harmonic-producing loads (like VFDs, UPS) are present. Capacitor damage and potential system instability due to amplification of harmonic currents.
• Detuned PFC includes series reactors (inductors) with the capacitor banks to shift the resonant frequency away from typical harmonic frequencies (e.g., 5th, 7th).
• Use Case: Designed for harmonic-rich environments (plants with VFDs, soft starters, computers, etc.). Prevents the capacitors from becoming a resonant trap for harmonics.
• Benefits: Protects capacitors from harmonic overload. Improves system stability and ensures safe reactive power compensation. Helps maintain compliance with IEEE 519 or similar standards.

Rule of Thumb: If your system includes non-linear loads, always use detuned PFC to avoid costly failures or harmonic amplification. If you have a lot of non-linear loads, then you may need to consider an Active Harmonic Filter.