Quick Reference of Diesel Generator Set-(Part-1)


Standard Size of The DG sets

KVA KVA KVA KVA KVA
7.5 KVA 20KVA 35 KVA 62.5 KVA 100 KVA
10 KVA 25 KVA 40 KVA 75 KVA 125 KVA
15 KVA 30 KVA 50 KVA 82.5 KVA 200 KVA

  

Bar Size for D.G Foundation

Rating of D.G set Size of Bar
Up to 82.5 KVA 10MM
100 KVA To 200 KVA 12MM
250 KVA to 500KVA 16MM

  

Minimum Capacity of Daily Fuel Service Tank  (AS per CPWD)

Capacity of DG set Minimum Fuel Tank Capacity
Upto 25 KVA 100 Litres
Above 25 to 62.5 KVA 120 Litres
Above 62.5 KVA to 125 KVA 225 Litres
Above 125 KVA to 200 KVA 285 Litres
Above 200 KVA to 380 KVA 500 Litres
Above 380 KVA to 500 KVA 700 Litres
Above 500 KVA to 750 KVA 900 Litres

  

Battery Size for D.G Set  (AS per CPWD)

DG Set Capacity Battery Capacity (AH) Cu Cable Size (Sq. mm) Electrical System (Volts)
Upto 25 KVA 88 35 12
Above 25 KVA upto 62.5 KVA 120 50 12
Above 62.5 KVA upto 82.5 KVA 150 50 12
Above 82.5.KVA upto 125 KVA 180 50 12
Above 125 KVA upto 500 KVA 180 70 12
Above 500 KVA 360 70 24

  

Depths of PCC (Plain Cement Concrete)  for DG Set (As per CPWD)
DG Set Capacity (KVA) Typical Depth of PCC Foundation (For soil bearing capacity 5000 kg/sqm)
750-2000 600 mm
625 400 mm
320-500 400 mm
200-320 400 mm
82.5 -200 400 mm
Upto 82.5 200 mm

 

Area Required For Generator in Electrical Sub Station (As per NBC)

Capacity  kVA Area m2 Clear Height below the Soffit of the Beam m
25 56 3.6
48 56 3.6
100 65 3.6
150 72 3.6
248 100 4.2
350 100 4.2
480 100 4.2
600 110 4.6
800 120 4.6
1010 120 6.5
1250 120 6.5
1600 150 6.5
2000 150 6.5

 

 

Starting Current for D.G set

Type of Load Starting Current
Motors over 50 HP 6 X motor rated current
Variable frequency drive motors 2 X motor rated current
Uninterruptible power supply (UPS) loads 1.5 X UPS rated current
Battery charger loads 2.5 X Charger rated current
Non-Linear Load 1.5 to 2.5 X rated current
Medical imaging loads 1.1 X Rated current
Soft Starter Motor 1.2 X motor rated current
DOL Starter 4 X motor rated current
Star-Delta Starter 3 X motor rated current
Auto Transformer Starter 1.5 X motor rated current
Most generators are capable of delivering 300% of the rated current for 10 seconds

 

 

Stand by D.G Permission As per PSEB

D.G Set Capacity Permission Remarks
Up to 10 KW(11 KVA) No permission is required. Also prior sanction of CEI is not required.  
10 KW (11 KVA) to 250 KVA
250 KVA to 1 MVA
1 MVA to 2.5 MVA Permission is required. Also prior sanction of CEI is required The capacity of D.G Set should not exceed 1.2 times of the sanctioned Load.
2.5 MVA to 5 MVA
Exceeding 5 MVA

 

Sound Level of Diesel Generator (ANSI 89.2&NEMA 51.20):

KVA Max. Sound Level
<9 KVA 40 DB
10 KVA to 50 KVA 45 DB
51 KVA to 150 KVA 50 DB
151 KVA to 300 KVA 55 DB
301 KVA to 500 KVA 60 DB

 

Exhaust Stack Height

Up to 1000KVA D.G Total Height of stack (Meter) = (Height of Building Where D.G Installed +0.2 ) X √D.G Capacity in KVA
More than 1000KVA D.G 30 Meter height or more than 3 meter height of building which is higher.

 

Height of stack (Meter)

Generator Sets Total Height of Stack in Meters.
000 to 050 KVA Height of Building + 1.5 Meter
050 to 100 KVA Height of Building + 2.0 Meter.
100 to 150 KVA Height of Building + 2.5 Meter
150 to 200 KVA Height of Building + 3.0 Meter
200 to 250 KVA Height of Building + 3.5 Meter
250 to 300 KVA Height of Building + 4.0 Meter.

 

D.G Room Air Requirement

D.G Set Air Requirement
275 KVA 605 Cu. Meter / Min
320 KVA 625 Cu. Meter / Min
400 KVA 854 Cu. Meter / Min
500 KVA 1065 Cu. Meter / Min
600 KVA 1286 Cu. Meter / Min

 

Noise Limit of D.G Set As per CPWD, India

Up to 1000 KVA (manufactured after 2005) =75 dB(A) at 1 meter from the enclosure surface
The acoustic enclosure or acoustic treatment of the room shall be designed for minimum 25 dB(A) insertion loss or for meeting the ambient noise standards, whichever is on the higher side.
The measurement for insertion loss may be done at different points at 0.5 m from the acoustic enclosure / room, and then averaged.
The DG set shall be provided with proper exhaust muffler with insertion loss of minimum 25 dB(A).

  

Foundation & Earthing for D.G Set  (As Per CPWD)

Iteam Descriptions
D.G set inside Room A PCC foundation (1:2:4, M-20 grade) of approximate depth 150 mm above the finished Genset Room Floor level
The  length  and  breadth  of  foundation  should  be  at  least  250  mm   more on all sides than the size of the enclosure.
D.G set in Open Room A PCC (1:2:4, M-20 grade) foundation  of  weight  2.5  times  the  operating  weight  of  the  Genset  with  enclosure  or  as recommended by the Genset manufacturer, whichever is higher
300 mm of this foundation height should be above the ground level. The length and breadth of foundation should be at least 250 mm more on all sides than the size of enclosure.
Earthing Copper plate earthing (Neutral Grounding) shall be provided for DG Sets of capacity 500 KVA or above
whereas G.I. plate earthing (Neutral Grounding) shall be provided for DG Sets below 500 KVA capacity. The body earthing shall generally be of G.I
Numbers of earthing for each DG Sets 2No’s  earthing sets for Genset/ control panel body.
2No’s earthing sets for neutral.
In case there are more than one DG Set in one location, independent two nos. neutral earthing shall be provided for each DG set. However, two nos. earthing sets shall be common for the body earthing of DG Sets
DG Set of 500 KVA capacity or above:- Copper strip
DG Set below 500 KVA capacity:- GI strip

  

D.G Spacing Guidance

Description DG set with Acoustic Enclosure Open DG set in room.
in Open Area in Closed Area
Free space on both sides Min. 1.5 m Min. 1.5 m Min. 2 m
Free space at front side (Radiator Hot air outlet at Front) Min. 3 m Min. 3 m N/A
Free space at front side (Radiator Hot air outlet at Top) Min. 1.0 m Min. 1.5 m N/A
Free space at rear side
(Alternator)
Min. 2 m Min. 2 m Min. 2 m
Fresh air inlet opening area N/A N/A Min 1.5 times of the Radiator area.
Hot air discharge opening area N/A N/A Min 2.5 times of the Radiator area.
Distance between two sets Min 1.5m between two
canopies
Min 1.5m between
two canopies
Min 1.5m between two foundations.

 

D.G Detail according to Size

D.G Size (KVA) L x W x H (Canopy) mm Approx Weight (Kg) Fuel Tank (Ltrs) Fuel Consumption (Ltr/hr) Oil Consumption (Ltr/hr)
12.5 2040 x 1230 x 1450 1050 60 2.3 0.02
15 2040 x 1230 x 1450 1050 65 2.3 0.02
20 2240 x 1230 x 1450 1300 65 3.7 0.03
30 2510 x 1130 x 1450 1300 65 6.3 0.03
40 3350 x 1180 x 1650 1500 100 7.8 0.03
50 3350 x 1180 x 1650 1500 100 8.3 0.03
62.5 3350 x 1180 x 1650 1930 150 10.5 0.03
75 3605 x 1405 x 1600 1950 150 13 0.03
100 3940 x 1700 x 1850 2500 300 15.7 0.05
125 3950 x 1700 x 1850 2700 300 19 0.05
140 4600 x 1850 x 1950 3580 300 22.6 0.06
160 4600 x 1850 x 1950 3720 450 25.9 0.14
180 4970 x 1730 x 2045 3870 450 27.7 0.14
200 4970 x 1730 x 2045 3950 450 29.8 0.14
250 4970 x 1730 x 2050 4660 450 37.7 0.15
275 5700 x 2030 x 2515 5860 450 50 0.15
320 5700 x 2030 x 2515 5860 450 57 0.3
400 5905 x 2030 x 2520 6180 990 65.1 0.3
500 6205 x 2030 x 2550 6990 990 81.3 0.3

 

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