8
Operating profile
Annual running time
In other words, this is the total operating time per year (h). Enter the estimated
number of hours that the pump is expected to run during a year’s time. For 24
hour, 365-day operation, enter 8760 hours.
Operating Time at Different Flow Rates (%)
Enter the estimated time as a percentage of the total operating time for
operation at each of the listed flow rates from 100% to 20% of nominal volume
flow. Leave blank or enter zero for flow rates that are not used. The sum of the
entered percentages should be 100%. A figure under the white cells shows if
the sum equals 100. If it does not, a comment “
THIS SUM MUST EQUAL
100!
” shows.
Economic Data
Currency
Specify here the currency to be used in calculations. The default unit is the
Euro (EUR).
Energy price (per kWh)
Enter the price of energy per kilowatt-hour (kWh). The PumpSave program
does not have provisions for calculating demand charges. To estimate energy
cost including demand charges, enter the average cost of energy per kWh
including average demand charges.
Investment cost
Enter the estimated additional cost of purchasing and installing a variable
speed AC drive as compared to the alternative method of flow control used in
the comparison. Use the same currency units as entered for energy cost. This
entry will be used to calculate the direct payback time.
Interest rate (%)
This is the compensation for capital in the net present value calculation.
Service Life (years)
The expected service life of the drive. Also this is required for the net present
value calculation.
Results
The results of the calculations include the estimated annual energy
consumption for the existing control method and for AC drive control, the
difference of these two, which equals the annual energy saving achieved by
using a variable speed AC drive. PumpSave also estimates the reduction in
carbon dioxide (CO
2
) emissions due to the reduced electricity consumption.
CO
2
is the most important of the greenhouse gases, which cause a global
environmental problem called the climate change.
Payback period is calculated for the investment in the drive as compared to the
alternative method of flow control. Net present value is also calculated
provided that the user enters an interest rate and service life.
