Danfoss VLT FC 102 Programming Manual page 227

Parameter Descriptions
3.21.5 23-8* Payback Counter
The frequency converter includes a feature which can give a rough calculation on payback in cases where the frequency
converter has been installed in an existing plant to ensure energy savings. Reference for the savings is a set value to
represent the average power yielded before the upgrade with variable-speed control.
P
Illustration 3.71 Variable-speed Control
The difference between the reference power at fixed speed and the actual power yielded with speed control represent the
actual saving.
As value for the fixed speed case, the rated motor size (kW) is multiplied with a factor (set in %) representing the power
produced at fixed speed. The difference between this reference power and the actual power is accumulated and stored. The
difference in energy can be read in parameter 23-83 Energy Savings.
The accumulated value for the difference in power consumption is multiplied with the energy cost in local currency and the
investment is subtracted. This calculation for cost savings can also be read in parameter 23-84 Cost Savings.
Cost Savings =
t
∑ Rated Motor Power ∗ Power Reference Factor
t = 0
− Actual Power Consumption × Energy Cost
− Investment Cost
Breakeven (payback) occurs when the value read in the parameter turns from negative to positive.
It is not possible to reset the energy savings counter, but the counter can be stopped any time by setting
parameter 23-80 Power Reference Factor to 0.
Parameter for settings
Rated motor power
Power reference factor in %
Energy cost per kWh
Investment
Table 3.28 Parameter Overview
M0010001
Programming Guide
Rated power for the
motor size used
(P 1-20/21)
Reference power
(at xed speed)
(P 23-80)
Actual power yielded
with variable
speed control
(read P 16-10/11)
Parameter 1-20 Motor Power [kW]
Parameter 23-80 Power Reference
Factor
Parameter 23-81 Energy Cost
Parameter 23-82 Investment
Danfoss A/S © 10/2019 All rights reserved.
Parameters for readout
Energy savings
Actual power
Cost savings
Parameter 23-83 Energy Savings
Parameter 16-10 Power [kW],
parameter 16-11 Power [hp]
Parameter 23-84 Cost Savings
225
3 3