Electrical Formulas
Delta Transformer Voltage Formula
Eline = Ephase
Ohm's Law
E = IR (E - Voltage; I - Current; R - Resistance)
Wye Transformer Voltage Formula
Eline = Ephase(sqrt3)
Delta Transformer Current Formula
Iline = Iphase(sqrt3)
Ohm's Law Power Formula
P = IE (P - Power; I - Current; E - Voltage)
Resistance in a Parallel Circuit
Rt = 1/(1/R1+1/R2+1/R3)
Voltage in a Parallel Circuit
Same across each branch of the circuit
Current in a Parallel Circuit
The sum of current across each branch of the circuit
Voltage Drop Formula (Three Phase)
VD = (sqrt3)KIL/Acmil (VD - Voltage Drop; K - Specific Resistance; I - Current; Acmil - Area measured in circular mils)
Voltage Drop Formula (Single Phase)
VD = 2KIL/Acmil (VD - Voltage Drop; K - Specific Resistance; I - Current; Acmil - Area measured in circular mils)
Voltage in a Series Circuit
Voltage is shared between components
Delta Transformer Apparent Power (kVA) Formula
kVAline = EI(sqrt3)/1000 kVAphase = kVAline/3
Wye Transformer Apparent Power (kVA) Formula
kVAline = EI(sqrt3)/1000 kVAphase = kVAline/3
Wye Neutral Return Formula
sqrt[a^2 + b^2 + c^2 - (ab) - (bc) - (ca)]
Resistance in a Series Circuit
total resistance = sum of individual resistances
Wye Transformer Current Formula
Iline = Iphase
Current in a Series Circuit
Same at all points