note on generator transformer sizing

[saraswatapalit]

Please help by providing a detail note on generator transformer sizing. What are the factors that governs this rating?

thanks in advance

best regard

saraswata

[admin]

In sizing a transformer used as secondary output for a generator, the following things have to be considered:

1. the size, in KVA, must not be less than the max KVA rating of the generator. remember that some generators have a service factor of 10% above the max nameplate rating.

2. the voltage and frequency also play a vital role in the selection of a transformer.

3. we do not size the transformers at 100% loading but we have to consider demand factor, usually at 85%.

4. i presume that that the size of the generator was computed based on the known loads (and future loads).

[jones]

saraswatapalit said:

Please help by providing a detail note on generator transformer sizing. What are the factors that governs this rating?

thanks in advance

best regard

saraswata

---

please tell us in details, where  u want to use them . untill and unless get the idea how u want to use them. location of the transformer and generator in the SLS how we are going to tell u.

definaltely there are some basic rules:

u can get the max efficiency of the dg set @75 percantage loading. Transformer loading charactersticsh should be in considerrations.

connected load is also a consideration , coz as per the load it will provide the dips of the voltage during starting.

if this is the main t/f of the incomer substation then u have consider lots more other parameter.

[Spir Georges GHALI]

saraswatapalit said:

Please help by providing a detail note on generator transformer sizing. What are the factors that governs this rating?

thanks in advance

best regard

saraswata

---

Dear ;

 

For exp. you have a factory for which you should define the sizes of Transforme & Genrator, first, you should know the following :

– The total installed power in this factory

– The loads that are running in normal working ” P “

– The kind of loads ” Single Phase  or  3 Phases ” and how the ditribution will be done for the single phase loads

– The average value of Cos φ for the factory ( we can calculate it if we know the Cos φ for each load )

– After that we should know an idea if there's some extention and the total power of it

Then the needed apparent power is : S1 = P( total ) / Cos φ, and ad the needed apparent power should be less the power of the transformer by ” 15-20% “, we can say that the apparent power of the transformer is : S ( tr ) = S1 / 0.8

So accordingly to the value of calculated ” S ” we can do our choice of the real transformer from the standard rating that are : 25, 50, 100, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, 2500, 3200, 4000, 6300 kVA

 

For the generator, we should know the vital loads that should be always in running, once we know, we do the same procedure to define the power of generator, noting that once the generator runs it should be loaded at teast 45% of his power.

 

Regards.

[redstargenerator]

Thanks for sharing this great information about the detail note on generator transformer sizing. And, what are ht efactors that governs this rating. I found this post really helpful and informative.

________________
Generators

[Author]

Posts