Calculate Size of Diesel Generator for various types of Load

June 21, 2024 Leave a comment


Calculate Size of Diesel Generator set for following types of various equipment’s

D.G Set Detail:

  • G Set Phase-Phase Voltage=415V, Phase-Neutral Voltage=230V, Future Load expansion=10%, D.G overload capacity =130%.

Connected Load:

  1. Fire Fighting Pump: 1No,3 Phase, 90KW, starting P.F is 0.7 & running P.F is 0.8, Soft Starter, Continuous use.
  2. HVAC Load: 1No, 3 Phase, 20KW, starting P.F is 0.7 & running P.F is 0.8, Intermediate use.
  3. UPS Load: 1No, 3 Phase, 7KW, starting P.F is 0.7 & running P.F is 0.8, Continuous use.
  4. Lighting Load: 10No, 1Phase ,400Watt, starting P.F is 0.7 & running P.F is 0.8, Continuous use.
  • Linear Load =General Electrical equipment, Heater
  • Non-Linear Load = UPS, Inverter, Ballast, Drives

CALCULATION:

LOAD NO:1 (MOTOR LOAD)

  • Total Load (KW)= No of Equipment X Size of Equipment
  • Total Load (KW)=01×90 =90KW
  • Diversify Load (KW)= Total Load X Duty factor (0=Stand by Load,1=continuous Load, 0 to 1 =Intermediate Load)
  • Diversify Load (KW) = 90×1= 90KW————————————–(1)
  • Running KVA = Diversify Load (KW) / Running P.F
  • Running KVA = 90 x 0.8
  • Running KVA =113 KVA————————————–(2)
  • Running Amp (Amp) = Diversify Load (KW) / 1.732 x Volt x Running P.F
  • Running Amp (Amp) =90×1000 / 1.732 x 415 x 0.8
  • Running Amp (Amp) =156.7 Amp
  • Starting Amp = Running Amp X Multiplying Factor of Starter
  • Multiplying Factor of Starter is as under.
Starter Starting current
Method Starting current
Direct-on-Line (DOL) 5 to 10 times the full load current
Star-Delta Starter 3 to 4 times the full load current
Auto-transformer 2 to 3 times the full load current
Soft starter 1.1 to 2 times full load current
Variable Speed drive 1.1 to 1.5 times full load current
  • Considering Multiplying Factor for Soft Starter is 2
  • Starting Amp = 156.7 X 2
  • Starting Amp =313Amp
  • Starting KVA = (Diversify Load (KW) / Starting P.F) X Multiplying Factor of Starter
  • Starting KVA = (90/0.7) X 2
  • Starting KVA = 257 KVA——————————————–(3)

LOAD NO:2 (HVAC LOAD)

  • Total Load (KW)= No of Equipment X Size of Equipment
  • Total Load (KW)=01×20 =20KW
  • Diversify Load (KW)= Total Load X Duty factor (0=Stand by Load,1=continuous Load, 0 to 1 =Intermediate Load)
  • Diversify Load (KW) = 20×0.8= 16KW————————————–(4)
  • Running KVA = Diversify Load (KW) / Running P.F
  • Running KVA = 16 x 0.8
  • Running KVA =20 KVA————————————–(5)
  • Running Amp (Amp) = Diversify Load (KW) / 1.732 x Volt x Running P.F
  • Running Amp (Amp) =16×1000 / 1.732 x 415 x 0.8
  • Running Amp (Amp) =28 Amp
  • Starting Amp = Running Amp X Multiplying Factor of HVAC
  • Multiplying Factor of Starting Current for various type of Load is as under.

Starting current
Type of Load Starting current for Load
Linear 1 time the full load current
Non-Linear 1.2 to 1.6 times the full load current
HVAC 1.2 to 1.5 times the full load current
  • Considering Multiplying Factor of HVAC is 1.3
  • Starting Amp = 28X 1.3
  • Starting Amp =36Amp
  • Starting KVA = (Diversify Load (KW) / Starting P.F) X Multiplying Factor of HVAC
  • Starting KVA = (16/0.7) X1.3
  • Starting KVA = 30 KVA——————————————–(6)

LOAD NO:3 (NON-LINEAR LOAD)

  • Total Load (KW)= No of Equipment X Size of Equipment
  • Total Load (KW)=01×7 =7KW
  • Diversify Load (KW)= Total Load X Duty factor (0=Stand by Load,1=continuous Load, 0 to 1 =Intermediate Load)
  • Diversify Load (KW) = 7×1= 7KW————————————–(7)
  • Running KVA = Diversify Load (KW) / Running P.F
  • Running KVA = 7 x 0.8
  • Running KVA =9 KVA————————————–(8)
  • Running Amp (Amp) = Diversify Load (KW) / 1.732 x Volt x Running P.F
  • Running Amp (Amp) =7×1000 / 1.732 x 415 x 0.8
  • Running Amp (Amp) =12 Amp
  • Starting Amp = Running Amp X Multiplying Factor of Non-Linear Load
  • Multiplying Factor of Starting Current for various type of Load is as under.

Starting current
Type of Load Starting current for Load
Linear 1 time the full load current
Non-Linear 1.2 to 1.6 times the full load current
HVAC 1.2 to 1.5 times the full load current
  • Considering Multiplying Factor of Non-Linear Load (UPS) is 1.6
  • Starting Amp = 12X 1.6
  • Starting Amp =19Amp
  • Starting KVA = (Diversify Load (KW) / Starting P.F) X Multiplying Factor of HVAC
  • Starting KVA = (7/0.7) X1.6
  • Starting KVA = 16 KVA——————————————–(9)

LOAD NO:4 (LINEAR LOAD)

  • Total Load (KW)= No of Equipment X Size of Equipment
  • Total Load (KW)=10×0.4 =4KW
  • Diversify Load (KW)= Total Load X Duty factor (0=Stand by Load,1=continuous Load, 0 to 1 =Intermediate Load)
  • Diversify Load (KW) = 4×1= 4KW————————————–(10)
  • Running KVA = Diversify Load (KW) / Running P.F
  • Running KVA = 4 x 0.8
  • Running KVA =5 KVA————————————–(11)
  • Running Amp (Amp) = Diversify Load (KW) / 1.732 x Volt x Running P.F
  • Running Amp (Amp) =4×1000 / 230 x 0.8
  • Running Amp (Amp) =22 Amp
  • Starting Amp = Running Amp X Multiplying Factor of Linear Load
  • Multiplying Factor of Starting Current for various type of Load is as under.

Starting current
Type of Load Starting current for Load
Linear 1 time the full load current
Non-Linear 1.6 times the full load current
HVAC 1.2 to 1.5 times the full load current
  • Considering Multiplying Factor of Linear Load is 1
  • Starting Amp =22×1
  • Starting Amp =22Amp
  • Starting KVA = (Diversify Load (KW) / Starting P.F)
  • Starting KVA = (4/0.7)
  • Starting KVA = 6 KVA——————————————–(12)

TOTAL LOAD CALCULATION:

  • Total Starting KVA= Starting KVA of (Load 1+ Load 2+ Load 3 +Load 4)
  • Total Starting KVA= 257+30+16+6
  • Total Starting KVA= 309 KVA————————————(A)
  • Total Running KVA =Running KVA of (Load 1+ Load 2+ Load 3 +Load 4)
  • Total Running KVA =113+20+9+5
  • Total Running KVA = 146 KVA—————————–(B)
  • D.G set Size (KVA) = Total Starting KVA x Future Load Expansion.
  • D.G set Size (KVA) = 309×1.1 (10% Future expansion)
  • D.G set Size (KVA) = 339 KVA—————————————-(C)

CONDITION FOR SELECTING D.G SET:

  • CONDITION-1:
  • Total Non-Linear Load < 30% of D.G Size
  • Here Value no (9) < Value no (C)
  • 16 KVA < 102 KVA
  • Condition-1 is full fill
  • CONDITION-2:
  • Overloads withstand Capacity of D.G > Total Required starting KVA
  • Overload withstand capacity of D. G= D.G size X D.G over Load Capacity
  • Overload withstand capacity of D. G= 339 x 130%
  • Overload withstand capacity of D. G= 401 KVA——————–(D)
  • Total Required starting KVA = Total Load (KVA) -Largest Motor rating (KVA)+ Largest Motor starting (KVA)
  • Total Required starting KVA =146 -113+257
  • Total Required starting KVA =291 KVA ————————(E)
  • Here Value no (D) > Value no (E)
  • 401 KVA > 291 KVA
  • Condition-2 is full fill

 CONCLUSION:

  • Here Condition-1 & Condition-2 is full fill hence selected D.G Size is OK.
  • Hence D.G size is 339 KVA or near its 380 KVA

 

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