MIL-HDBK-1133
2.6.3
Process for Estimating Electric Transmission Losses.
The following steps define the process for estimating electric
transmission losses using the forms shown in Tables 9 and 10:
a) Identify the time period to be considered such as
month, season, or year. Identify the peak load for that time
period from the utility bill. Calculate the total nameplate
capacity by summing the kVA rating of all transformers.
Calculate the average load by dividing the total kilowatt-hours
consumed by the total hours in the time period. Enter each of
these values in Table 9.
b) From the values entered and derived in Step 1,
calculate the (FDLS), (FLD), and (FELS) factors using Equations
2, 3, and 4 and enter on Table 9.
c) Enter No. of Phases, Voltage, Capacity, and No. of
Units information for each transformer type in Table 10. For
each transformer or group of transformers, find the appropriate
Load Loss and No-Load Loss values in Table D-1 in Appendix D and
enter on Table 10. If the transformer does not appear in the
table, extrapolation can be used, or check with the manufacturer
to determine the losses.
d) Using Equations 5 and 6, calculate the Energy Loss
and Demand Loss for each transformer or group of transformers.
Note: The example in Table 10 uses summer values and number of
hours in one season.
e) Sum all transformer loss values to create total
installation transformer energy and demand loss values.
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