Food Processing Plant Expansion in Central Ontario

Scenario

A frozen food packaging facility in Guelph, Ontario expanded its production line with six new refrigeration compressors (total connected load: 850 kW). The existing 400 V, 3-phase service operated at 0.68 PF due to legacy induction motors and uncorrected lighting ballasts. Hydro One’s tariff requires minimum 0.90 PF to avoid demand charge penalties. Ambient conditions include winter temperatures down to −25°C and summer peaks up to 35°C indoors; capacitor derating and cold-start reliability were critical. Site harmonic survey revealed low THD (<3%), confirming suitability for standard capacitors.

Given Data

• Real Power: 850 kW
• Initial Power Factor: 0.68
• Target Power Factor: 0.90
• Voltage: 400 V

Calculation

$$ \phi_1 = \cos^{-1}(0.68) \approx 47.16^\circ,\quad \tan(\phi_1) \approx 1.086 \ \phi_2 = \cos^{-1}(0.90) \approx 25.84^\circ,\quad \tan(\phi_2) \approx 0.484 $$

$$ Q_c = 850 \cdot (1.086 - 0.484) = 850 \cdot 0.602 = 511.7 \text{ kVAR} $$

Using the tool with inputs {"real_power": 850, "initial_pf": 0.68, "target_pf": 0.90, "voltage": 400} yields 511.70 kVAR.

Result and Decision

A 520 kVAR fixed + automatic hybrid bank was installed: 300 kVAR fixed (for base-load refrigeration) and 220 kVAR automatic (for variable packaging line loads), all using −40°C rated dry-type polypropylene film capacitors with self-healing metallization. Units were grouped in thermally isolated cabinets with internal heaters (activated below 0°C) and digital temperature monitoring. Post-commissioning verification confirmed sustained 0.91–0.93 PF across all shifts.

Lesson

Capacitor selection must account for extreme ambient temperature ranges: standard units lose >20% capacitance at −25°C and risk dielectric breakdown during cold starts — always specify wide-temperature-grade components and integrate thermal management, not just electrical ratings.