VFD Energy Saving - Cube-Law Pump

Energy saved when a centrifugal pump or fan is speed-controlled instead of throttled. Affinity P ∝ N³ makes small speed reductions huge energy wins.

MotorsVFDAffinity

Shaft power at 100 % speedkWOperating speed share%Operating hours / yearhElectricity priceUSD/kWh

Shaft power at current speed: 76.80kW

Energy saved / year: 439,200kWh

USD saved / year: 79,056USD

Changing the inputs requires JavaScript. The calculator above shows its default inputs and result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

P(N) = P_\text{full} \cdot \left(\frac{N}{N_\text{full}}\right)^3

Symbol	Meaning	Unit
$P_\text{full}$	Shaft power at rated speed	kW
$N$	Operating speed	% of full
$h$	Operating hours	h/yr

Source: IMO MEPC.282(70) - SEEMP energy-efficiency measures

In short

Energy saved when a centrifugal pump or fan is speed-controlled instead of throttled.

Learn the theory Marine Electrical Generation and Distribution