Voltage Drop Calculation Basis
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Three-Phase % Voltage Drop = Calculated Current in Amps * Effective Z * (Wire Length / 1,000) * 100 / Line-to-Neutral Voltage
Single-Phase % Voltage Drop = Calculated Current in Amps * Effective Z * (Wire Length / 1,000) * 100 * 2 / Line-to-Neutral Voltage
Effective Z = R cos(theta) + X sin (theta) (NEC Table 9 Note 2)
R = Resistance set in the command.
X = Reactance set in the command.
theta = Power factor of the electrical system.
Line-to-Neutral Voltage is used based upon NEC Table 9 Note 2: "Multiplying current by effective impedance gives a good approximation for line-to-neutral voltage drop."
The wire impedance values are based upon NEC Table 9. These values can be modified by the user using the command.
Calculated Current in Amps is the Total Estimated Demand Current on the electrical equipment. This load is calculated by Revit based upon the loads connected to the electrical equipment and the demand factors.
Wire Length is the Feeder Length value for the panel. Set the feeder length using the command.
Branch Circuit Values
Calculated Current in Amps is the the Apparent Current on the circuit. This load is calculated by Revit based upon the devices connected to the circuit.
Wire Length is the Circuit Length value for the circuit. Set the circuit length using the command. The voltage drop calculation assumes the entire circuit load is located this distance from the panel.
Transformer Voltage Drop Basis
The transformer impedance values are for dry-type indoor transformers. These values can be modified by the user using thecommand or command.
The voltage drop through transformers can be included, ignored, or reset to 0. Use the Transformer voltage drop calculation method option in the command to control how the voltage drop is calculated.
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