Calculate Size of Diesel Generator


Calculate Size of Diesel Generator having following Electrical Load. Consider Future Expansion ratio is 10%. Average use of Equipment is 0.8 (1 is Full Time Use)

  • 4 No’s of 1Ph, 230V, 80Watt CFL Bulbs, Diversity Factor is 0.8; Starting & Running P.F is 0.8.
  • 2 No’s of 1Ph, 230V, 3000Watt Air Condition, Diversity Factor is 1, Starting & Running P.F is 0.8.
  • 2 No’s of 1Ph, 230V, 500Watt Halogen Lights Diversity Factor is 0.8 Starting & Running P.F is 0.8.
  • 1 No’s of 1Ph,230V, 10KW Motor with Y-D Starter, Diversity Factor is 0.8,Starting P.F is 0.7 & Running P.F is 0.8
  • 1 No’s of 3Ph,430V, 130KW Motor with Soft Starter , Diversity Factor is 0.8,Starting P.F is 0.7 & Running P.F is 0.8

Calculation:

Type of Load Equipment Starting Current
Linear Load General Equipment
100% of Full Load Current
Non-Linear Load UPS, Inverter, Computer, Ballast 160% of Full Load Current

 

Type of Starter Starting Current
DOL 6 X Full Load Current
Star-Delta 4 X Full Load Current
Auto Transformer 3 X Full Load Current
Soft Starter 2 X Full Load Current
VFD 1.5 X Full Load Current

 

Load Calculation-1:

  • Full Load KW of CFL Bulb=(No X Watt X Diversity Factor) /1000
  • Full Load KW of CFL Bulb=(4x80x0.8)/1000=0.3KW
  • Full Load KVA of CFL Bulb=KW / P.F
  • Full Load KVA of CFL Bulb=0.3 / 0.8=0.4KVA————(H)
  • Full Load current of CFL Bulb=(No X Watt X Diversity Factor) / (Volt x P.F)
  • Full Load current of CFL Bulb=(4x80x0.8) / (230×0.8) =2 Amp—-(M)
  • Type of Load=Linear
  • Starting KVA of CFL Bulb=1 X (KW / Starting P.F)
  • Starting KVA of CFL Bulb=0.3 / 0.8=0.4KVA———————-(1)
  • Starting Current=100% of Full Load Current.
  • Starting Current=1 X 2= 2 Amp.————–(A)

Load Calculation-2:

  • Total Full Load KW of A.C=(No X Watt X Diversity Factor) /1000
  • Total Full Load KW of A.C =(2x3000x0.8)/1000=4.8KW
  • Total Full Load KVA of A.C =KW / P.F
  • Total Full Load KVA of A.C =4.8 / 0.8=6KVA————(I)
  • Total Full Load current of A.C =(No X Watt X Diversity Factor) / (Volt x P.F)
  • Total Full Load current of A.C =(2x3000x0.8) / (230×0.8) =26 Amp——-(N)
  • Type of Load=Non Linear
  • Starting KVA of A.C=1.6 X (KW / Starting P.F)
  • Starting KVA of A.C =1.6 X (4.8 / 0.8)=9.6KVA———————-(2)
  • Starting Current=160% of Full Load Current.
  • Starting Current=1.6 X 26= 42 Amp. ————–(B)

Load Calculation-3:

  • Full Load KW of Halogen Bulb=(No X Watt X Diversity Factor) /1000
  • Full Load KW of Halogen Bulb=(2x500x0.8)/1000=0.8KW
  • Full Load KVA of Halogen Bulb=KW / P.F
  • Full Load KVA of Halogen Bulb=0.8 / 0.8=1KVA————(J)
  • Full Load current of Halogen Bulb=(No X Watt X Diversity Factor) / (Volt x P.F)
  • Full Load current of Halogen Bulb=(2x500x0.8) / (230×0.8) =4 Amp—-(O)
  • Type of Load=Non Linear
  • Starting KVA of Halogen Bulb =1.6 X (KW / Starting P.F) / Starting P.F
  • Starting KVA of Halogen Bulb =1.6 X (0.8 / 0.8)=1.6KVA———————-(3)
  • Starting Current=160% of Full Load Current.
  • Starting Current=1.6 X 4= 7 Amp .————–(C)

Load Calculation-4:

  • Full Load KW of Motor=(No X Watt X Diversity Factor) /1000
  • Full Load KW of Motor =(1x10000x0.8)/1000=8KW
  • Full Load KVA of Motor =KW / P.F
  • Full Load KVA of Motor =8 / 0.8=10KVA————(K)
  • Full Load current of Motor =(No X Watt X Diversity Factor) / (Volt x P.F)
  • Full Load current of Motor =(1x10000x0.8) / (230×0.8) =43 Amp—-(P)
  • Type of Starter=Star-Delta
  • Starting KVA of Motor =4 X (KW / Starting P.F)
  • Starting KVA of Motor=4X (8 / 0.7)=45.7KVA————————(4)
  • Starting Current=4 X Full Load Current
  • Starting Current=4 X 11.4 = 174 Amp.————–(D)

Load Calculation-5:

  • Full Load KW of Motor=(No X Watt X Diversity Factor) /1000
  • Full Load KW of Motor =(1x120000x0.8)/1000=96KW
  • Full Load KVA of Motor =KW / P.F
  • Full Load KVA of Motor =96 / 0.8=120KVA————(L)
  • Full Load current of Motor =(No X Watt X Diversity Factor) / (Volt x P.F)
  • Full Load current of Motor =(1x120000x0.8) / (1.732x430x0.8) =167 Amp—-(Q)
  • Type of Starter=Auto Transformer
  • Starting KVA of Motor =3 X (KW / Starting P.F)
  • Starting KVA of Motor=3 X (96 / 0.7)=411.4KVA—————(5)
  • Starting Current=3 X Full Load Current
  • Starting Current=3 X 167 = 501 Amp.————–(E)

Total Load Calculation:

  • Total Starting KVA = (1) + (2) +(3) + (4) + (5)
  • Total Starting KVA =0.4+9.6+1.6+45.7+411.4 =468.7 KVA
  • Total Starting Current = (A) + (B) +(C) + (D) + E
  • Total Starting Current =2+42+7+174+501= 725 Amp
  • Total Running KVA =(H)+(I)+(J)+(K)+(L)
  • Total Running KVA =4+6+1+10+120= 137KVA
  • Total Running Current=(M)+(N)+(O)+(P)+(Q)
  • Total Running Current=2+26+4+43+167= 242 Amp
  • Size of Diesel Generator= Starting KVA X Future Expansion X Average Use of Equipments
  • Size of Diesel Generator=468.7 X 1.1 X 0.8
  • Size of Diesel Generator= 412 KVA

Summary:

  • Total Starting KVA =468.7 KVA
  • Total Starting Current =725 Amp
  • Total Running KVA = 137KVA
  • Total Running Current= 242 Amp
  • Size of Diesel Generator= 412 KVA
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