Why PFI Plants Are Mandatory in Bangladesh
In AC electrical distribution systems, inductive equipment such as electric motors, transformers, welding sets, and air conditioning compressors draw lagging reactive current. This circulating reactive power converts electrical energy into parasitic heat, drops line voltage, and increases loading on cables, switchgears, and power transformers.
In Bangladesh, power distribution utilities (BPDB, BREB, DPDC, DESCO, WZPDCL, NESCO) penalize consumers whose power factor falls below 0.95 (lagging). Installing an engineered SETB Automatic PFI Plant restores power factor to 0.98 – 0.99, permanently wiping out penalty charges, releasing substation capacity, and reducing electricity bills.
Anatomy of SETB PFI Panels
Built with genuine European and Japanese components for prolonged operational life under harsh tropical conditions:
Dry Cylindrical Capacitors
Heavy-duty self-healing metalized polypropylene capacitors filled with eco-friendly gas/resin. Overpressure tear-off disconnectors prevent catastrophic case rupture during end-of-life breakdown.
Microprocessor PFC Relays
Digital 6-step to 16-step automatic regulators (Mikro, EPCOS, Schneider) measuring current from CTs, monitoring THD, and rotating step operations evenly to prolong capacitor life.
Damped Capacitor Contactors
Special contactors with pre-insertion early-make contacts and damping resistor wires to absorb high-frequency inrush currents up to 200x rated current during switching.
Detuned Harmonic Reactors
Optional 7% or 14% detuned copper filter reactors installed in series with capacitors in plants with Variable Frequency Drives (VFD) to prevent parallel resonance disasters.
Typical PFI Plant Sizing Guidelines Based on Transformer Capacity
| Transformer Rating (kVA) | Recommended PFI Bank (kVAR) | Step Switching Configuration | Target Resulting Power Factor |
|---|---|---|---|
| 100 kVA | 40 – 60 kVAR | 5 + 10 + 15 + 20 kVAR (4 Steps) | 0.98 Lagging |
| 250 kVA | 100 – 150 kVAR | 10 + 15 + 25 + 50 kVAR (6 Steps) | 0.985 Lagging |
| 500 kVA | 200 – 300 kVAR | 15 + 25 + 50 + 50 + 50 kVAR (8 Steps) | 0.99 Lagging |
| 630 kVA | 250 – 350 kVAR | 25 + 25 + 50 + 50 + 50 + 50 kVAR (8 Steps) | 0.99 Lagging |
| 1000 kVA | 400 – 600 kVAR | 25 + 50 + 50 + 100 + 100 + 100 kVAR (10 Steps) | 0.99 Lagging |
| 1500 kVA | 600 – 900 kVAR | 50 + 50 + 100 + 100 + 100 + 100 + 100 kVAR (12 Steps) | 0.99 Lagging |
| 2000 kVA | 800 – 1200 kVAR | 50 + 100 + 100 + 100 + 100 + 100 + 100 + 100 kVAR (14 Steps) | 0.99 Lagging |