Trane TR200 - Page 244

23-8* Payback Counter
The adjustable frequency drive includes a feature which can give a rough calculation on payback in cases where
the adjustable frequency drive has been installed in an existing plant to ensure energy savings by changing
from fixed to variable speed control. Reference for the savings is a set value to represent the average power
yielded before the upgrade with variable speed control.
The difference between the Reference Power at fixed speed and the Actual Power yielded with speed control
represent the actual savings.
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 accu-
mulated and stored. The difference in energy can be read in par.23-83
Energy Savings.
The accumulated value for the difference in power consumption is multiplied with the energy cost in local cur-
rency and the investment is subtracted. This calculation for cost savings can also be read in par.23-84
Cost
Savings.
Cost Savings =
{

t =0
t
(
Rated Motor Power Ӓ Power Reference Factor
)
ì Actual Power Consumption × Energy Cost
}
ì Investment Cost
Break even (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 par.
23-80
Power Reference Factor to 0.
Parameter overview:
Parameter for settings
Parameters for readout
Rated Motor Power par.1-20 Motor Power
[kW]
Energy Savings par.23-83 Energy Savings
Power Reference Factor in
%
par.23-80 Power Refer-
ence Factor
Actual Power par.16-10 Power [kW],
par.16-11
Power [hp]
Energy Cost per kWh par.23-81 Energy Cost Cost Savings par.23-84 Cost Savings
Investment par.23-82 Investment
Parameter Description
TR200 Programming Guide 4-207