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              ELECTRICAL DISTRIBUTION SYSTEM

Single line diagram, three phase short circuit current calculations, phase to ground short circuit current calculations, two phase to ground short circuit currents calculations.

1-Short Circuit Current Calculations According to Per Unit Method

2-Short Circuit Current Calculations According to Impedance (Ohmic) Method

3-Short Circuit Current Calculations According to MVA Method

4-Creating a Single Line Diagram

 

 

 

  Upstream Network Sks=1453 MVA V=154 kV Ankara Balgat TM Zı=(0,0069+j.0,0681) pu Zo=(0,0069+j.0,1363) pu Str = 40 MVA %Uk =11,7 Zı =(0+j.0,1462) pu Zo =(0+j.0,1462) pu 2 Unit 3(1x240) I3f=6,803kA Ift=0,455kA 114 m 1 Circuit zı=(0,0004+j. 0,0011) pu zo=(0,0036+j.0,0044) pu 3(1x240) 1 🗲 114 m 1 Circuit 3(1x240) 2 🗲 I3f=5,124kA Ift=0,438kA 3610 m 1 Circuit zı=(0,0271+j.0,0686) pu zo=(0,2168+j.0,2744) pu 3(1x240) 3 🗲 I3f=4,522kA Ift=0,43kA 1923 m 1Circuit zı=(0,0144+j.0,0365) pu zo=(0,1152+j.0,146) pu 3(1x240) 4 🗲 I3f=4,16kA Ift=0,423kA 1415 m 1 Circuit zı=(0,0106+j. 0,0269) pu z0=(0,0848+j.0,1076) pu 3x477 MCM 🗲 5 I3f=3,527kA Ift=0,426kA 6236m 1 Circuit zı=(0,075+j.0,192) pu z0=(0,225+j.0,6144) pu 3x477 MCM 🗲 6 I3f=2,595kA Ift=0,404kA 4571 m 1 Circuit zı=(0,055+j.0,1407) pu z0=(0,205+j.0,4502) pu 3x477 MCM 🗲 7 I3f=2,243kA Ift=0,39kA 2698 m 1Circuit zı=(0,0325+j.0,0831) pu z0=(0,1825+j.0,2659) pu 400 V 🗲 8 I3f=28,19kA Ift=18,35kA Str1 = 1600 kVA %Uk1 = 11,7 400 V Str2 = 1600 kVA %Uk2 = 11,7 🗲 9 I3f=26,3kA Ift=17,32kA Resistance =61 Ω Zo =(3,0738+j.0) pu 31,5 kV İ.M DM 1 DM 5 DM 6 DM 7 DM 2 DM 3 DM 4

                                              

                            Upstream Network:

          Network Short Circuit Power: MVA

                            Network Voltage: kV 

        Step down Transformer Power: MVA

                             Secondary Voltage:

  Relative Short Circuit Voltage%Uk:

          Parallel Transformers Number:  

      Transformer Neutral Resistance: Ω 

       Transformer Connection Group:

   Copper Cable    Aluminum Cable      Overhead Line   

                        İM-DM.1 Conductor:

                             Conductor Length: m

                                 Circuit Number:  

   Copper Cable      Aluminum Cable        Overhead Line    

                   DM.1-DM.2 Conductor:

                            Conductor Length: m

                                Circuit Number:  

   Copper Cable      Aluminum Cable        Overhead Line 

                   DM.2-DM.3 Conductor:

                            Conductor Length: m

                                 Circuit Number:  

   Copper Cable      Aluminum Cable        Overhead Line     

                       DM.3-DM.4 Conductor:

                                Conductor Length: m

                                     Circuit Number:  

   Copper Cable      Aluminum Cable         Overhead Line   

                          DM.1-DM.5 Conductor:

                                  Conductor Length: m

                                       Circuit Number:  

   Copper Cable       Aluminum Cable        Overhead Line     

                          DM.5-DM.6 Conductor:

                                   Conductor Length: m

                                        Circuit Number:  

   Copper Cable       Aluminum Cable        Overhead Line 

                          DM.6-DM.7 Conductor:

                                   Conductor Length: m

                                       Circuit Number:  

1.Distribution Transformer Power Str1: kVA

                                   Secondary Voltage:

      Relative Short Circuit Voltage%Uk:

            Transformer Connection Group:

 2.Distribution Transformer Power Str2: kVA

                                     Secondary Voltage:

        Relative Short Circuit Voltage%Uk:

              Transformer Connection Group:

          

 

                                                   

*In the calculation of reactance values: HV underground cables are single and laid underground at 7 cm distance, and in overhead lines, flatcross arm and dm = 1.1 m are taken.

Calculations Based on 100 (Per Unit Method):

Upstream Network :ZUpstream Network=100/Sk pu XUpstream Network=0,98.ZUpstream Network  ,  RUpstream Network=0,1.XUpstream Network

Tranformer : Xtr=Uk/S pu

Conductor: Rh=R.L.100/Vn2 pu

 

-Three Phase Short Circuit Calculations :

 X1(1)=Xs+Xtr(1)+Xh1(1) =0,0681+0,1462+0,0011=0,2154 pu

 R1(1)=Rs+Rtr(1)+Rh1(1) =0,0069+0+0,0004=0,0073 pu

  Z1(1)=R1(1)+j X1(1) =0,0073+ j 0,2154=0,2155 pu

 Ik3''=6,803 kA

-Phase Ground short circuit calculations

 X0(1)=Xs0+Xtr0(1)+Xh0(1) =0,1363+0,1462+0,0044=0,2869 pu

 R0(1)=Rs0+Rtr0(1)+3.Rn+Rh0(1) =0,0069+0+9,2214+0,0036=9,2319 pu

 Z0(1)=R0(1)+j X0(1) =9,2319+ j 0,2869=9,2364 pu

 Z0(1)/Z1(1) =9,2364/0,2155=42,86 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 6,803 x     3           =  0,455 kA

                          2+ Z0                    2+ 42,86

                                Z1

 Three phase short circuit current is greater than phase-to-ground short circuit current

-Peak Asymmetrical Current Calculations

IEC 60909 standardına göre tepe akımı:

k1=1,02+0,98 e(-3R/x) =1,91

Ip1= k.√2 . Ik3'' =18,376 kA

-Thermal Short Circuit Current

At a point far from the generator Ik3''/Ik3=1 and  n=1

 m=              1                    [ e4.f.Tk.ln(K-1)-1]= 0,106

         2.f.Tk.Ln(K-1)

Ith=Ik3''.√(m+n) = 6,803

Breaker Power : Sksc=√3.Un.1,1.Ik3''=√3.36.1,1.6,803= 467  MVA

-Three Phase Short Circuit Calculations :

 X1(2)=Xs+Xtr(1)+Xh1(1)+Xh1(2)=0,0681+0,1462+0,0011+0,0686=0,284 pu

 R1(2)=Rs+Rtr(1)+Rh1(1)+Rh1(2) =0,0069+0+0,0004+0,0271=0,0344 pu

  Z1(2)=R1(2)+j X1(2) =0,0344+ j 0,284=0,2861 pu

 Ik3''=5,124 kA

 

-Phase Ground short circuit calculations

 X0(2)=Xs0+Xtr0(1)+Xh0(1)+Xh0(2) =0,1363+0,1462+0,0044+0,2744=0,5613 pu

 R0(2)=Rs0+Rtr0(1)+3.Rn+Rh0(2) =0,0069+0+9,2214+0,0036+0,2168=9,4487 pu

 Z0(2)=R0(2)+j X0(2) =9,4487+ j 0,5613=9,4654 pu

 Z0(2)/Z1(2) =9,4654/0,2861=33,08 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 5,124 x     3           =  0,438 kA

                          2+ Z0                    2+ 33,08

                                Z1

  Three phase short circuit current is greater than phase-to-ground short circuit current

-Peak Asymmetrical Current Calculations

IEC 60909 standardına göre tepe akımı:

k2=1,02+0,98 e(-3R/x) =1,7

Ip2= k.√2 . Ik3'' =12,319 kA

-Thermal Short Circuit Current

At a point far from the generator Ik3''/Ik3=1 and  n=1

 m=              1                    [ e4.f.Tk.ln(K-1)-1]= 0,028

         2.f.Tk.Ln(K-1)

Ith=Ik3''.√(m+n) = 5,124

Breaker Power: Sksc=√3.Un.1,1.Ik3''=√3.36.1,1.5,124= 351  MVA

 

 

-Three Phase Short Circuit Calculations :

 X1(3)=Xs+Xtr(1)+Xh1(1)+Xh1(2)+Xh1(3)=0,0681+0,1462+0,0011+0,0686+0,0365=0,3205 pu

 R1(3)=Rs+Rtr(1)+Rh1(1)+Rh1(2)+Rh1(3) =0,0069+0+0,0004+0,0271+0,0144=0,0488 pu

  Z1(3)=R1(3)+j X1(3) =0,0488+ j 0,3205=0,3242 pu

 Ik3''=4,522 kA

 

-Phase Ground short circuit calculations

 X0(3)=Xs0+Xtr0(1)+Xh0(1)+Xh0(2)+Xh0(3)=0,1363+0,1462+0,0044+0,2744+0,146=0,7073 pu

 R0(3)=Rs0+Rtr0(1)+3.Rn+Rh0(1)+Rh0(2) +Rh0(3)  =0,0069+0+9,2214+0,0036+0,2168+0,1152=9,5639 pu

 Z0(3)=R0(3)+j X0(3) =9,5639+ j 0,7073=9,59 pu

 Z0(3)/Z1(3) =9,59/0,3242=29,58 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 4,522 x     3           =  0,43 kA

                          2+ Z0                    2+ 29,58

                                Z1

 Three phase short circuit current is greater than phase-to-ground short circuit current

-Peak Asymmetrical Current Calculations

Peak current according to IEC 60909 standard:

k3=1,02+0,98 e(-3R/x) =1,64

Ip3= k.√2 . Ik3'' =10,488 kA

-Thermal Short Circuit Current

At a point far from the generator Ik3''/Ik3=1 and  n=1

 m=              1                    [ e4.f.Tk.ln(K-1)-1]= 0,0224

         2.f.Tk.Ln(K-1)

Ith=Ik3''.√(m+n) = 4,522

Breaker Power : Sksc=√3.Un.1,1.Ik3''=√3.36.1,1.4,522= 310  MVA

 

-Three Phase Short Circuit Calculations :

 X1(4)=Xs+Xtr(1)+Xh1(1)+Xh1(2)+Xh1(3)+Xh1(4)=0,0681+0,1462+0,0011+0,0686+0,0365++0,0269=0,3474 pu

 R1(4)=Rs+Rtr(1)+Rh1(1)+Rh1(2)+Rh1(3)+Rh1(4) =0,0069+0+0,0004+0,0271+0,0144+0,0106=0,0594 pu

  Z1(4)=R1(4)+j X1(4) =0,0594+ j 0,3474=0,3524 pu

 Ik3''=4,16 kA

 

-Phase Ground short circuit calculations

 X0(4)=Xs0+Xtr0(1)+Xh0(1)+Xh0(2)+Xh0(3)+Xh0(4)=0,1363+0,1462+0,0044+0,2744+0,146+0,1076=0,8149 pu

 R0(4)=Rs0+Rtr0(1)+3.Rn+Rh0(1)+Rh0(2) +Rh0(3)+Rh0(4)  =0,0069+0+9,2214+0,0036+0,2168+0,1152+0,0848=9,6487 pu

 Z0(4)=R0(4)+j X0(4) =9,6487+ j 0,8149=9,6831 pu

 Z0(3)/Z1(3) =9,6831/0,3524=27,48 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 4,522 x     3           =  0,423 kA

                          2+ Z0                    2+ 27,48

                                Z1

 Three phase short circuit current is greater than phase-to-ground short circuit current

-Peak Asymmetrical Current Calculations

Peak current according to IEC 60909 standard:

k4=1,02+0,98 e(-3R/x) =1,61

Ip4= k.√2 . Ik3'' =9,472 kA

-Thermal Short Circuit Current

At a point far from the generator Ik3''/Ik3=1 and  n=1

 m=              1                    [ e4.f.Tk.ln(K-1)-1]= 0,0202

         2.f.Tk.Ln(K-1)

Ith=Ik3''.√(m+n) = 4,16

Breaker Power : Sksc=√3.Un.1,1.Ik3''=√3.36.1,1.4,16= 285  MVA

-Three Phase Short Circuit Calculations :

 X1(5)=Xs+Xtr(1)+Xh1(1)+Xh1(5)=0,0681+0,1462+0,0011+0,192=0,4074 pu

 R1(5)=Rs+Rtr(1)+Rh1(1)+Rh1(5) =0,0069+0+0,0004+0,075=0,0823 pu

  Z1(5)=R1(5)+j X1(5) =0,0823+ j 0,4074=0,4156 pu

 Ik3''=3,527 kA

 

-Phase Ground short circuit calculations

 X0(5)=Xs0+Xtr0(1)+Xh0(1)+Xh0(5)=0,1363+0,1462+0,0044+0,6144=0,9013 pu

 R0(5)=Rs0+Rtr0(1)+3.Rn+Rh0(1)+Rh0(5)  =0,0069+0+9,2214+0,0036+0,225=9,4569 pu

 Z0(5)=R0(5)+j X0(5) =9,4569+ j 0,9013=9,4998 pu

 Z0(5)/Z1(5) =9,4998/0,4156=22,86 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 4,522 x     3           =  0,426 kA

                          2+ Z0                    2+ 22,86

                                Z1

 Three phase short circuit current is greater than phase-to-ground short circuit current

-Peak Asymmetrical Current Calculations

Peak current according to IEC 60909 standard:

k5=1,02+0,98 e(-3R/x) =1,55

Ip5= k.√2 . Ik3'' =7,731 kA

-Thermal Short Circuit Current

At a point far from the generator Ik3''/Ik3=1 and  n=1

 m=              1                    [ e4.f.Tk.ln(K-1)-1]= 0,0167

         2.f.Tk.Ln(K-1)

Ith=Ik3''.√(m+n) = 3,527

Breaker Power: Sksc=√3.Un.1,1.Ik3''=√3.36.1,1.3,527= 242  MVA

 

 

-Three Phase Short Circuit Calculations :

 X1(6)=Xs+Xtr(1)+Xh1(1)+Xh1(5)+Xh1(6)=0,0681+0,1462+0,0011+0,192+0,1407=0,5481 pu

 R1(6)=Rs+Rtr(1)+Rh1(1)+Rh1(5)+Rh1(6) =0,0069+0+0,0004+0,075+0,055=0,1373 pu

  Z1(6)=R1(6)+j X1(6) =0,1373+ j 0,5481=0,565 pu

 Ik3''=2,595 kA

 

-Phase Ground short circuit calculations

 X0(6)=Xs0+Xtr0(1)+Xh0(1)+Xh0(5)+Xh0(6)=0,1363+0,1462+0,0044+0,6144+0,4502=1,3515 pu

 R0(6)=Rs0+Rtr0(1)+3.Rn+Rh0(1)+Rh0(5)+Rh0(6) =0,0069+0+9,2214+0,0036+0,225+0,205=9,6619 pu

 Z0(6)=R0(6)+j X0(6) =9,6619+ j 1,3515=9,756 pu

 Z0(6)/Z1(6) =9,756/0,565=17,27 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 4,522 x     3           =  0,404 kA

                          2+ Z0                    2+ 17,27

                                Z1

 Three phase short circuit current is greater than phase-to-ground short circuit current

-Peak Asymmetrical Current Calculations

Peak current according to IEC 60909 standard:

k5=1,02+0,98 e(-3R/x) =1,48

Ip5= k.√2 . Ik3'' =5,431 kA

-Thermal Short Circuit Current

At a point far from the generator Ik3''/Ik3=1 and  n=1

 m=              1                    [ e4.f.Tk.ln(K-1)-1]= 0,0136

         2.f.Tk.Ln(K-1)

Ith=Ik3''.√(m+n) = 2,595

Breaker Power : Sksc=√3.Un.1,1.Ik3''=√3.36.1,1.2,595= 178  MVA

-Three Phase Short Circuit Calculations :

 X1(7)=Xs+Xtr(1)+Xh1(1)+Xh1(5)+Xh1(6)+Xh1(7)=0,0681+0,1462+0,0011+0,192+0,1407+0,0831=0,6312 pu

 R1(7)=Rs+Rtr(1)+Rh1(1)+Rh1(5)+Rh1(6)+Rh1(7)=0,0069+0+0,0004+0,075+0,055+0,0325=0,1698 pu

  Z1(7)=R1(7)+j X1(7) =0,1698+ j 0,6312=0,6536 pu

 Ik3''=2,243 kA

 

-Phase Ground short circuit calculations

 X0(7)=Xs0+Xtr0(1)+Xh0(1)+Xh0(5)+Xh0(6)+Xh0(7)=0,1363+0,1462+0,0044+0,6144+0,4502+0,2659=1,6174 pu

 R0(7)=Rs0+Rtr0(1)+3.Rn+Rh0(1)+Rh0(5)+Rh0(6)+Rh0(7) =0,0069+0+9,2214+0,0036+0,225+0,205++0,1825=9,8444 pu

 Z0(7)=R0(7)+j X0(7) =9,8444+ j 1,6174=9,9764 pu

 Z0(7)/Z1(7) =9,9764/0,6536=15,26 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 4,522 x     3           =  0,39 kA

                          2+ Z0                    2+ 15,26

                                Z1

 Three phase short circuit current is greater than phase-to-ground short circuit current

-Peak Asymmetrical Current Calculations

Peak current according to IEC 60909 standard:

k5=1,02+0,98 e(-3R/x) =1,46

Ip5= k.√2 . Ik3'' =4,631 kA

-Thermal Short Circuit Current

At a point far from the generator Ik3''/Ik3=1 and  n=1

 m=              1                    [ e4.f.Tk.ln(K-1)-1]= 0,0129

         2.f.Tk.Ln(K-1)

Ith=Ik3''.√(m+n) = 2,595

Breaker Power: Sksc=√3.Un.1,1.Ik3''=√3.36.1,1.2,243= 154  MVA

 

 

-Three Phase Short Circuit Calculations :

 X1(8)=Xs+Xtr(1)+Xh1(1)+Xh1(2)+Xh1(3)+Xh1(4)+Xstr(1)=0,0681+0,1462+0,0011+0,0686+0,0365+0,0269+3,75=4,0974 pu

 R1(8)=Rs+Rtr(1)+Rh1(1)+Rh1(2)+Rh1(3)+Rh1(4)+Rh1(5)+Rstr(1)  =0,0069+0+0,0004+0,0271+0,0144+0,0106+0=0,0594 pu

  Z1(8)=R1(8)+j X1(8) =0,0594+ j 4,0974=4,0978 pu

 Ik3''=0,358 kA

 LV Side Three Phase Short Circuit :  Ik3AG''=  Ik3''. Vp/Vs = 28,19 kA

-Phase Ground short circuit calculations

 X0(8)=Xs0+Xtr0(1)+Xh0(1)+Xh0(2)+Xh0(3)+Xh0(4)+Xstr10(1)=0,1363+0,1462+0,0044+0,2744+0,146+0,1076+3,75=4,5649 pu

 R0(8)=Rs0+Rtr0(1)+3.Rn+Rh0(1)+Rh0(2) +Rh0(3)+Rh0(4)+Rstr10(1) =0,0069+0+9,2214+0,0036+0,2168+0,1152+0,0848+0=9,6487 pu

 Z0(8)=R0(8)+j X0(8) =9,6487+ j 4,5649=10,6741 pu

 Z0(8)/Z1(8) =10,6741/4,0978=2,6 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 0,358 x     3           =  0,233 kA

                          2+ Z0                    2+ 2,6

                                Z1

 Three phase short circuit current is greater than phase-to-ground short circuit current 

LV Side Phase Ground Short Circuit :  Ik1fAG''=  Ik1f''. Vp/Vs = 18,35 kA

-Three Phase Short Circuit Calculations :

 X1(9)=Xs+Xtr(1)+Xh1(1)+Xh1(5)+Xh1(6)+Xh1(7)+Xstr(1)=0,0681+0,1462+0,0011+0,192+0,1407+0,0831+3,75=4,3812 pu

 R1(9)=Rs+Rtr(1)+Rh1(1)+Rh1(5)+Rh1(6)+Rh1(7)+Rstr(1)=0,0069+0+0,0004+0,075+0,055+0,0325+0=0,1698 pu

  Z1(9)=R1(9)+j X1(9) =0,1698+ j 4,3812=4,3845 pu

 Ik3''=0,334 kA

LV Side Three Phase Short Circuit :  Ik3AG''=  Ik3''. Vp/Vs = 26,3 kA

 

-Phase Ground short circuit calculations

 X0(9)=Xs0+Xtr0(1)+Xh0(1)+Xh0(5)+Xh0(6)+Xh0(7)+Xstr0(1)=0,1363+0,1462+0,0044+0,6144+0,4502+0,2659+3,75=5,3674 pu

 R0(9)=Rs0+Rtr0(1)+3.Rn+Rh0(1)+Rh0(5)+Rh0(6)+Rh0(7)+Rstr0(1) =0,0069+0+9,2214+0,0036+0,225+0,205+0,1825+0=9,8444 pu

 Z0(9)=R0(9)+j X0(9) =9,8444+ j 5,3674=11,2125 pu

 Z0(9)/Z1(7) =11,2125/4,3845=2,56 > 1 the phase-to-ground short circuit current is greater than the two phase-to-ground fault currents.

  Ik1t''= Ik3''x      3           = 0,334 x     3           =  0,22 kA

                          2+ Z0                    2+ 2,56

                                Z1

LV Side Phase Ground Short Circuit:  Ik1fAG''=  Ik1f''. Vp/Vs = 17,32 kA