Answer / vivek sri

A correction to my earlier answer(8)

In case we are to use a 3 phase generator then the total
current of 218.75 has to be equally shared between the 3
phases i.e. Iph=218.75/3=72.9 Amps.
So the genset rating would be again 52.5kVA(1.732*415*72.9).
But in actual as the number of AC's is 20;
18 Ac's get distributed equally (6 on each phase L-N) and
the balance 2 nos will be on one phase each.
So the max current will be 76.58 (18/3*10.94+10.94).
So the 3 phase genset rating would be 55kVA (1.732*415*76.58)

Answer / avnish sharma

I do agree with Mr. Prakash. but he has not considered pf, safety margin, and Future accommodation.

Answer / girijapati mishra

TOTAL REF LOAD =1.5X20 =30 TR
1 TR = 3.5 KW
Thus , 30 TR = 105 KW
COP (i.e ratio of heat removed vs power input ) for AC
varies from 2.5 to 3 depending on design and other
considerations.

Assuming a COP 2.5 ( lower side)
Power required will be 42 kw (=105/2.5).
Considering power factor 0.8 ( gen assumption for all
caculations) rating of the DG set will be 52.5kva ( =42/0.8)
. A DG set higher than this calculated value to to selected
for this requirement.

Answer / sathish reddy

45 KVA Diesel Genset is requied. Calculation is as follows,

20 * 1.5 = 30
Multiply by the MF 1.4
i.e. 30*1.4 = 42 KVA
As after 40 KVA we have 45 KVA as next higher capacity we
have to go by 45 KVA.

Answer / lokesh thota

Actually a 1.5tonn a/c will take 15amp at its maximum level
on 220v supply.so,for 20 such ac's you will need around 300
amps from that you can calculate how much Kva d.g u r need
with according to the vol you r selecting

Answer / jenifer

"Genset Engineering Calc" Version 1.1 is well designed than 1.0

Answer / prakash suhane

Total Load in T.R = 20X1.5 =30 T.R

1 T.R = 3.5 kw

for 30 T.R 30 X 3.5 = 105 K.w

any D.G set available more then 105 KVA is suitable for
this application.

Answer / jagjeet

Dear vIVEK,
Avinash has given correct answer , Generally pf of the
Dg Set is 0.8 and for calculation we are taking 20 %

Pf of Dg set is ==0.8
Safety Marging = 20 %
Future Expansion =20%
so 1.4*105/0.8=183KVA so you will have to go for 180 KVA
DG Set.

Answer / genset

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Answer / prakash veer singh

Dear vivak
first , we see.what is EER of used ac system , if ac EER
is 8. ac load less 20% .

then
1.5 ton= 18000 btu = 5.250kw
20 nos. acs load =20*5.250KW
= 105 KW
DG pf is 0.8 and DG safty margine is 20%.
than 105*1.4=147KVA

we use 150kva DG and more .

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