sizing of transformer

For sizing the transformer :-

1. Coonected load in KW

2. a Operational load in KW , b. Apply Load factor & c. Diversity of Operational load d. apply p.f and convert the load in KVA & e. sum and Total f. apply over all diversity.

3. The total KVA is demand load For India work out the loading of transfomrer as per IS 6600

4. Devide it by % efficiency of Transformer

5. Allow the continous operation safe operation considering 80 % size devide the figure of 4 by 80%

6. The round off KVA to next available standard size.

nascon

1. What is load factor( is it a ratio of max demand/connected load) ?

2. What is diversity of operational load?

EX ample my total connected load is 100 kw in which

lighting = 20 kw,small power = 30 kw,AC load= 50 kw

Diversity of of lighting = 100%( i.e 20kw x 1= 20 KW)

Diversity of small power =65% to 70%(30Kw x 0.7= 21 Kw)

Ac load - I am not sure how much to take

then please can you tell me in detail as per the steps mentioned by you what will be the size of transformer?

Light 20 kw +other 21 KW and for AC load , with load factor and over all diversity towards switching off during the preset temp , you can take as 70 % i.e with 50 x .7 = 35 kw total load works out to be 76 Kw i.e at o.85 p.f 89 .41 KVA considering TR average efficiency as 96 % = 93.14 KVA and for safety factor for continuous load allowable up to 80 % , the rating works out to be 116.42 KVA ., the KVA can be selected as 120 KVA OR 125 KVA

nascon

in the above example you have applied only diversity factor to individual load, sum up, pf and safty factor, then what about load factor and overall diversity factor. could you please put more light by taking a typical example, it wil be grate help to me because my ongoing project we have calculating size of trx as follows 1.25 x (100 %TCL in KVA + 50 % of intermittent load or pick individual load whichever is higher)

please help

thanks