In the world of industrial automation, a robust electrical cabinet is the beating heart of any operation. But what happens when that heart overheats? For every 10°C rise above the maximum operating temperature, the life expectancy of critical electronic components like PLCs, VFDs, and power supplies is typically cut in half.
Why Proper Thermal Management is Non-Negotiable
Heat is the number one enemy of electronics. Proper cooling ensures:
- Extended Component Lifespan: Prevents premature aging.
- Reliable Operation: Avoids intermittent faults and shutdowns.
- Reduced Maintenance: Fewer emergency repairs and replacements.
Step 1: Gather Your Critical Data
Before doing the math, collect these four values:
- Total Heat Loss (Pv): Total Watts generated by components inside.
- Surface Area (A): Total external surface area of the cabinet in m².
- Internal Temperature (Ti): Your target temperature inside (e.g., 35°C).
- Ambient Temperature (Te): The hottest it gets outside the cabinet.
Step 2: Calculate Natural Heat Dissipation
Your cabinet walls naturally release some heat. Use the formula below based on your material:
Pdissipated = k × A × (Ti - Te)
*k = 5.5 for Sheet Steel | k = 3.5 for Plastic/Polyester
Step 3: Determine the Net Heat (Pnet)
Subtract the natural dissipation from your total component heat:
Pnet = Pv - Pdissipated
Step 4: Calculate Required Airflow (V)
If you are using Leipole Fan Filters, use this formula to find the required airflow in m³/h:
V = (3.1 × Pnet) / ΔT
(Where ΔT = Ti - Te)
Quick Reference: Typical Heat Loss Values
| Component | Approx. Heat Loss (W) |
|---|---|
| Small PLC | 5 - 20 W |
| VFD / Inverter | 2% - 5% of rated power |
| Power Supply | 10% - 15% of output power |
Summary & Pro-Tips
- Safety Margin: Always add 10-20% to your calculated airflow to account for filter dust buildup.
- Check Te: If the outside temperature is higher than your target inside temperature, a fan won't work—you will need a Leipole Cabinet Air Conditioner.
