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.
130BA259.11
P
Actual power yielded
with variable
speed control
(read P 16-10/11)
Reference power
(at xed speed)
(P 23-80)
Rated power for the
motor size used
(P 1-20/21)
Illustration 3.71 Variable-speed Control
The dierence between the reference power at xed speed and the actual power yielded with speed control represent the
actual saving.
As value for the xed speed case, the rated motor size (kW) is multiplied with a factor (set in %) representing the power
produced at xed speed. The dierence between this reference power and the actual power is accumulated and stored. The
dierence in energy can be read in parameter 23-83 Energy Savings.
The accumulated value for the dierence 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.
CostSavings=
∑
t = 0
t
RatedMotorPower ∗ PowerReferenceFactor
− ActualPowerConsumption × EnergyCost
− 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 Parameters for readout
Rated motor power Parameter 1-20 Motor Power [kW] Energy savings Parameter 23-83 Energy Savings
Power reference factor in % Parameter 23-80 Power Reference
Factor
Actual power Parameter 16-10 Power [kW],
parameter 16-11 Power [hp]
Energy cost per kWh Parameter 23-81 Energy Cost Cost savings Parameter 23-84 Cost Savings
Investment Parameter 23-82 Investment
Table 3.28 Parameter Overview
Parameter Descriptions Programming Guide
M0010001 Danfoss A/S © 10/2019 All rights reserved. 225
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