Generator is a composite unit, which generates electricity. In case of electricity failure, generator provides backup electricity.

Important Components Of Diesel operated Generating Sets are : –

  1. Diesel engine.
  2. Alternator
  3. Control panel
  4. Radiator
  5. Battery
  6. Diesel tank
  7. Canopy
  8. Silencer
  9. Rain cap
  10. Exhaust piping
  11. Acoustic enclosure with doors
  12. Base frame

Load Calculations for deciding the capacity of a Generating set: –

Consider three buildings, of seven storeys each and every building having 2 bedroom apartments on each floor. The generator backup is given to the following appliances.

  1. Lift lighting
  2. Staircase lighting
  3. Parking lighting
  4. Street lighting
  5. Water pumps
  6. Pumps for the Fire fighting system.

Calculations for the required load for each building are as follows: –

Sr No.

Electrical Points at



Total load




40 W

320 W


Common Terrace


40 W

80 W




40 W

400 W


Lift & machine room


40 W

400 W


Lift motor


7.5 HP

7500 W


Pumps for Fire fighting


5 HP

5000 W



13700 W


i.e.13.7 KW

Load for Common lighting: –

  1. Water pumps – 2nos x 2.0 HP  = 4 HP = 4 kw
  2. Street lighting – 14nos x 40 = 560 W =0.56 kw Total common load = 4.56 KW

. : Total load = 3 buildings x load/building + load for common lighting

= 3 x 13.7 KW + 4.56 KW

= 45.66 KW

Applying diversity factor = as 0.70, designed capacity load

= 0.7 x 45.60 KW

= 31.962 KW

The capacity of the Generator required for the above load is = 35 KVA.

Civil works involved in the installation of D.G. set : –

  1. Foundation: – The details and sizes for the foundations given by the manufacturer,shall be followed..
  2. Installation of D.G. sets: – Install the D.G. set on the foundation in specified orientation by keeping workable space on all sides.
  3. Conduiting and cabling: – Cables shall be laid through RCC hume pipes or in trenches from D.G. set to meter room of each building. Provide feeder pillars of required capacity, at specified locations for the distribution of backup supply.
  4. Earthing: Provide earthing to body of the D.G. set, phase and feeder pillars as per the specified norms. Usually 6 nos. of earthings are provided.
  5. Change over switch: – Provide specified change-over switch.

Commissioning of generator: –

Commissioning of D.G. set should be done in the presence of the representative of the manufacturer and the electrical contractor. Commissioning should be done as per the check list provided by the manufacturer.

Each and every instruction from this checklist should be followed.

The system should be run for a period specified by the consultant before the final inspection. After the final inspection, all the necessary rectifications should be done and recorded.

Periodic checks of D.G. set: –

  1. Check level of engine oil, and top up required quantity of oil, if necessary.
  2. Check fuel level in fuel tank and protect the top of the tank.
  3. Check level of coolant in radiator and top up if necessary.
  4. Check for leakage of coolant, fuel and lube oil and rectify.
  5. Check if all instruments are functioning.

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