Sizing a Diesel Genset

Total HP = 1315; for starting the largest motor add 2x225 = 450 for grand total 1765 HP. Convert to KW; 1765 x 0.746 ≈ 1317 KW. Assuming 0.80 PF, 1317/0.80 ≈ 1054 KVA. Select a genset exceeding both of these ratings.

If you can do some power management to ensure that none of the 225-HP motors starts when all the others are running, you can recalculate this by replacing the 2x225 accordingly, which will allow a smaller genset.

1317/0.8=1646

and

1317*0.8=1054

Which one do you prefer ?

Thank you for catching my error. I see now what I did wrong: I hit "/" on the calculator rather than "*". My fingers don't always go to the right places. 1646 KVA it is.

See the earlier thread and the related links for more detail: http://cr4.globalspec.com/thread/58246/Power-Generator-Sizing

- MS

Question:

Calculate the GENSET capacity of the following motors.

4 Nos. 60HP = 60*746W = 44.76kW

3 Nos. 100HP = 100*746W = 74.6kW

3 Nos. 225HP = 225*746W = 167.85kW

Solution:

You Total load will be = 44.76*4 + 74.6*3 + 167.85*3

= 179.04 + 223.8 + 503.55

= 906.39kW

When sizing the capacity you need to consider worst case scenarios:-

(1) Running all motors except 1 Nos. 225HP which you plan to start via Y/D.

Genset Capacity = 179.06 + 223.8 + 335.7 + 167.85 * 3 (For Y/D)

= 1.25MW

(2) Running all 225HP motors, 60HP motors and 2 Nos. 100HP motors and you need to start 1 Nos. 100HP motor.

Genset Capacity = 179.06 + 149.2 + 74.6*3 + 505.3

= 1.06MW

(3) Running all 225HP motors, 100HP motors and 3 Nos. 60HP motors, then

Genset Capacity = 505.3 + 223.8 + 134.28 + 44.3*3

= 1MW

Scenario 1 shows maximum capacity so you would choose that. When sizing a Genset don't forget to consider future load as well.

Hope this helps.

Kindly look at MSamad link http://cr4.globalspec.com/thread/58246/Power-Generator-Sizing

Thank you all, for your painstaking efforts. Your words improved my knowledge. In future, I will need kind guidance from all of you.

Refer EC&M