Working with single phase, three-phase and DC (direct current circuits) and you quickly need to reference formulas for voltage drops and power calculations for a given conductor? The table below provides a quick reference for these calculations.
Voltage Drop and Power Calculation Formulas For Single Phase Circuits
| Electrical Parameters | Formulas |
| Voltage Drop | $∆V = 2*I*L*(rCosՓ + xSinՓ)$ |
| % Voltage Drop | % $∆V = \frac{∆V}{V_r}*100$ |
| Active Power | $P = V*I*CosՓ$ |
| Reactive Power | $Q = V*I*SinՓ$ |
| Apparent Power | $S = V*I = \sqrt{{P^2} +{Q^2}}$ |
| Power Factor | $CosՓ = \frac{P}{S}$ |
| Power Loss | $P_L = 2*L*r*I^2$ |
| Electrical Parameters | Formulas |
| Voltage Drop | $∆V = \sqrt{3}*I*L*(rCosՓ + xSinՓ)$ |
| % Voltage Drop | % $∆V = \frac{∆V}{V_r}*100$ |
| Active Power | $P = \sqrt{3}*V*I*CosՓ$ |
| Reactive Power | $Q = \sqrt{3}*V*I*SinՓ$ |
| Apparent Power | $S = \sqrt{3}*V*I = \sqrt{{P^2} +{Q^2}}$ |
| Power Factor | $CosՓ = \frac{P}{S}$ |
| Power Loss | $P_L = 3*L*r*I^2$ |
| Electrical Parameters |
Formulas
|
| Voltage Drop |
$∆V = 2*I*L*r$
|
| % Voltage Drop |
% $∆V = \frac{∆V}{V_r}*100$
|
| Active Power |
$P = V*I$
|
| Reactive Power |
$ - $
|
| Apparent Power |
$ - $
|
| Power Factor |
$ - $
|
| Power Loss |
$P_L = 2*L*r*I^2$
|
Meaning of symbols used in the formulas above:
$L$ = Total length of conductor
$r $ = Resistance of conductor per unit length
$x$ = Reactance of conductor per unit length
$∆V$ = Voltage drop
$P$ = Active power
$Q$ = Reactive power
$I$ = Current