temperature). The line current is calculated based on the expected real power

requirement and phase angle. The following equations show the calculation of line

current:

Single -Phase Circuits

where,

=

Line current in amperes

=

Real power, in kW

=

Voltage, RMS--in kV to match power units

=

Phase angle between voltage and current

Three-Phase Circuits

3 *V*L cos *θ*

where,

=

Line current in amperes

=

Total three-phase real power, in kW

=

Line voltage, RMS--in kV to match power units

=

Phase angle between voltage and current

B-2.3

If comparing voltage drops across different nominal voltages, reference

voltage drop calculations to a 120 volt base to allow ready comparison of the voltage

drops throughout the system, regardless of the actual voltage level. Use the following

expression to convert a voltage drop at some nominal voltage to a 120 volt base:

B-3

B-3.1

Transformer rated secondary current is calculated by dividing the rated kVA

capacity by the rated secondary voltage. The following examples illustrate the rated

secondary current calculation.

B-4

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