Voltage drop calculation

 Voltage drop calculation :

• Standard information Charts :-

Example :

Step 1.

            Convert kVA to Amp

            

                            kVA × 1.4 = A

                             100 × 1.4 = 140 A

Chart, 

            According it's chart we have to select

165 because after 135, 165 will come. So we will select 165 A it's rating is 95sq.mm

Step 2.

           Calculate the Resistant of the cable (from chart) for 95sq.mm we have 0.410 Ω/km.

For 1000m -- 0.410Ω 

        R(Ω) = length (mts) × Ω/km

                           1000       ×  No. of cable

                   60 M -- ?

             

              ? = 60 × 0.410 / 1000×1 = 0.0246 Ω

     Therefore, 60M -- 0.0246Ω

Step 3.

           Voltage drop calculation

   

Formula : √3 × I × R(Ω)

        

                 = 1.732 × 140× 0.0246

                 = 5.96

Therefore, As voltage drop is below 12 volts . So, 95sq.mm is recommended.

Example :

Step 1.

            Convert kVA to Amp

            

                            kVA × 1.4 = A

                             160 × 1.4 = 224 A

Chart, 

            According, So we will select 224 A it's rating is 185sq.mm

Step 2.

           Calculate the Resistant of the cable (from chart) for 185sq.mm we have 0.210 Ω/km.

For 1000m -- 0.210Ω 

        R(Ω) = length (mts) × Ω/km

                           1000       ×  No. of cable

                   75 M -- ?

             

              ? = 75 × 0.210 / 1000×1 = 0.0157 Ω

     Therefore, 75M -- 0.0157 Ω

Step 3.

           Voltage drop calculation

   

Formula : √3 × I × R(Ω)

        

                 = 1.732 × 224 × 0.0157

                 = 5.99

                 = 6

Therefore, As voltage drop is below 12 volts . So, 185sq.mm is recommended.