Variable Frequency Drive Energy Savings Calculator

The most common applications of using variable frequency drives are pumps and fans, suppose a 24/7 operate constant pressure water supply system's pump controlled by VFD may save as high as 30% electricity cost bills.

% Speed	% Hour
100%		Hours / Day Days / Week Hours / Week 168 Hours / Year 8,760
90%
80%
70%
60%
50%
40%
30%
20%
10%
	100 %

Motor size (HP):		Efficiency (%):
Input voltage (V):		Frequency (Hz):
Full load current (A):		Speed (RPM):

Full load input power (kW): 20.1 kW

VFD Cost ($):
Electricity rate ($/kWh):

Estimate annual operation cost without VFD: 15,860 $
Estimate annual operation cost with VFD: 7,988 $

Your Annual savings: 7,871 $
Payback time: 7.62 Months.

The "exact energy saving" is not possible to be calculated, due to many things going on when the variable frequency drive application is working, load change, material characteristics, efficiency, mechanical coupling, cycle of the process. Many VFD manufacturers have their own software and formula that can give you good value about energy savings estimation. But if you want to make good thing you've got to make the mechanical scheme, with efficiency of each and calculate for dedicated load the current used and see how much you have. This online cost saving calculator data is based on VFD for pumps and fans, the calculate result may differ from your actual applications.

For a retrofit replacing throttle control, it is well known proven fact that VFD reduces energy consumption in a large proportion and this variable speed drive technology has been in vogue since last 15 years in China. To site few successful examples - the ID/ FD fans for boilers and Fan pumps for pumping pulp in to Head box of a paper machine. If the application is having centrifugal load characteristics, variable frequency drive can be employed very gainfully with justifiable cost savings. Total replacement of a pump system also yields justifiable direct and intangible power savings. Each project to be evaluated individually and critically if need to be justified / quantified.