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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