The Physics of Your Savings
Our calculator uses the Centrifugal Affinity Laws to determine your Return on Investment. Here is the step-by-step logic:
1. Establishing the Power Baseline
First, we calculate the actual power your motor draws from the grid at 100% speed, accounting for Motor Efficiency:
Baseline Power = Motor kW / Motor Efficiency
2. The Cube Law (The VSD "Magic")
Unlike a lightbulb, centrifugal fans and pumps follow a Cubic Relationship. If you reduce the speed, the power required drops by the cube of that change:
Power Required = Baseline Power × (New Speed / Old Speed)³
Example: Running at 80% speed (0.8) requires only 51.2% of full power ($0.8 \times 0.8 \times 0.8 = 0.512$).
3. Accounting for Drive Losses
To ensure a realistic ROI, we apply a VSD Efficiency Factor (typically 97%) to account for the heat and internal cooling of the drive itself:
Total VSD Power = Power Required / Drive Efficiency
*Calculations are based on standard centrifugal load profiles and local utility rates. Actual savings may vary based on system static pressure and motor age.