18. DG sets

One day (10 hours) work shop on Diesel Generator Sets:

Module-1: (8AM to 10AM)
  • Introduction
  • What and why DG required
  • Types of DG sets
  • Sizing of DG

10 to 10:15 Break 

Module-2 (10:15 AM to 12: 15PM)
  • Parts of DG set
  • What is AVR in DG
  • Starting Procedure of DG
  • Installation of DG

12:15 to 12:45 : Lunch break

Module-3 (12 :45 PM to 2:45 PM)
  • Testing and pre commissioning of DG
  • Protection of DG

2:45 to 3:00 Break

Module-4 (3 PM to 5PM)

  • Maintenance of DG
  • Preventive maintenance
  • Shutdown maintenance
  • Trouble detection and trouble shooting of DG
  • How does AMF works for DG

5 PM to 6PM:

Question and Answers
Main Content:

  1. What is a DG
  2. Specification of DG
  3. Main components of DG
  4. Selection of DG
  5. Testing of DG
  6. Maintenance of DG
  7.  Random Interview Questions
  8. CPWD manual
  9. Typical Cables sizes as per CPWD
  10. Typical Battery sizes
  11. DG cost

1. What is a DG

  • DG is Diesel Generator
  • DG is a combination of Diesel Engine and alternator
  • DG is typically serves as a backup source to the electricity board supply for an apartment or facility
  • DG is typically rated in KVA
  • Standard ratings available are:
    • 415 V: 10/25/50/75/100/125/150/160/170/180/200/225/250/275/300/ 320/380/400/500/600/625/650/750/800/1050 KVA
    • 3.3/6.6/11 kV : 1250/1300/1460/1500/1750/2000/2200/3000/5000/6500/8000/12000 KVA
  • sample picture

2. Specification of DG

3. Main components of DG

  • Engine
  • Alternator
  • The fuel system
  • Voltage regulator
  • Cooling system
  • Exhaust system
  • Lubrication oil system
  • Starter and battery system
  • Control panel
    • Start / shut down controls (manual, automatic, or both)
    • Phase selector switch
    • Frequency switch
    • Engine mode switch
    • Engine fuel
    • Engine oil
    • Engine speed
    • Coolant temperature
    • Battery charge
    • Generator output voltage
    • Generator output current (amperage)
    • Generator Output in kVA
    • AC power frequency

4. Selection of DG

  • DG is rated in KVA
  • Selection of KVA rating of DG is nothing but sizing of DG
  • Sizing of a Genset:
    • a) If the DG set is required for 100% standby, then the entire connected load in HP / kVA should be added. 
    • Example :
      • Connected Load = 650 kW
      • Demand Factor = 0.54
      • (Demand / connected load)
      • Max. Demand = 650 x 0.54 = 350 kW
      • % Loading = 70
      • Set rating = 350/0.7 = 500 kW
      • At 0.8 PF, rating = 625 kVA
5. Testing of DG:

  • Load test
  • Insulation resistance test for Alternator
  • Functional tests
  • Measurement of Vibration
  • Noise level
Load Test - The engine shall be given test run for a period of at least 6 hours. The set shall be subjected to the maximum achievable load as decided by Purchaser without exceeding the specified DG Set rating. 

During the load test, half hourly records of the following shall have to be taken:
  • Load Test
    • Ambient temperature.
    • Exhaust temperature if exhaust thermometer is fitted.
    • Cooling water temperature at a convenient point adjacent to the water output from the engine jacket.
    • Lubricating oil temperature where oil cooler fitted.
    • Lubricating oil pressure.
    • Colour of exhaust gas 
    • Speed
    • Voltage, wattage and current output.
    • Oil tank level
  • Insulation Resistance test of alternator (Temporarily open alternator star point)
    • Insulation resistance in mega-ohms between the coils and the frame of the alternator 
    • when tested with a 500V megger shall not be less than IR=2x(rated voltage in 
    • KV)+1
    • Insulation resistance of control panel wiring shall be checked by 500V Megger. The IR shall not be less than one mega ohm
  • Functional Test
    • Functional tests on control panel.
    • Functional test on starting provision on the engine.
    • Functional tests on all Field devices.
    • Functional tests on AVR and speed governor.
6.  DG maintenance

  • Lubrication Service
  • Cooling System
  • Fuel System
  • Testing Batteries
  • Routine Engine Exercise
  • Keep your Diesel Generator Clean
  • Exhaust system inspection
A Standby Generator Maintenance Checklist

  • Weekly Maintenance
    • Run the generator (typically no-load, automatic transfer switch exercise cycle).
    • Verify that the unit ran and has no alarms or warnings
    • Ensure adequate fuel levels.
    • Ensure that the generator is in “Auto” mode, for automatic startup.
    • Check that the circuit breaker is closed.
    • Make sure there are no fluid leaks.
  • Monthly Maintenance
    • Check engine coolant level
    • Check engine oil level.
    • Check the battery charger.
  • Bi-Annual Maintenance (Schedule maintenance with a certified technician.)
    • Inspect the enclosure.
    • Check the battery electrolyte level and specific gravity.
    • Check battery cables and connections.
    • Inspect drive belts.
    • Inspect the coolant heater.
    • Check coolant lines and connections.
    • Check for oil leaks and inspect lubrication system hoses and connectors.
    • Check for fuel leaks and inspect fuel system hoses and connectors.
    • Inspect the exhaust system, muffler and exhaust pipe.
    • Check and clean air cleaner units.
    • Inspect air induction piping and connections.
    • Inspect the DC electrical system, control panel and accessories.
    • Inspect the AC wiring and accessories.
  • Annual Maintenance (Schedule maintenance with a certified technician.)
    • Change oil and filter.
    • Change the fuel filter.
    • Change the air filter.
    • Clean the crankcase breather.
    • Change spark plugs.
    • Check coolant concentration.
    • Flush the cooling system (as needed).
    • Perform load bank testing.
    • Fuel testing & reconditioning (diesel-fueled units only).
    • Remove water from fuel tank (diesel-fueled units only).

7. Random Interview Questions:
  • What is DG
  • Why DG required
  • DG name plate details
  • How do you select Dg for an application
  • Maintenance of DG
  • Tests of DG
  • Cost of DG
  • Manufacturers of DG
  • Per unit cost in DG
  • Diesel consumption per hour
  • What could be the job roles available
  • 10KVA DG cable size
  • 10 KVA DG earth wire size
  • Types of DGs available
  • Life of DG
  • Min and max capacities available
  • List of manufacturers
  • Standard ratings available 
  • What is the purpose of battery in DG
  • Why Dg rated in KVA not in KW
  • Can we connect two DGs in parallel
  • Can we synchronize solar with DG
8. CPWD manual

9. Typical Cable sizes for DG sets output
10. Typical battery sizes in DG sets

   11. DG cost:

    Some more Price data

  12. Important Data

  •     DG suppliers
    •      Mahindra Powerol
    •      Cummins
    •      Genesys

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