Rating Selection Criterion of GT, UAT and ST

Get the services of a competent electrical engineer locally. No CR4 members IMHO can see/visualise all your sorrow & do justice to your OP.

As Joshi already said it is a serious problem and only a specialized team with sufficient

experience can appreciate all these data.

You have to state the general scheme at 400 kV[H scheme,1 1/2 and so on] and state the medium voltage for Boiler Feed Water Pump motor and for Force Draft and Induce Draft Fan motors and other auxiliary-and so to state the UAT and ST necessary power. It is important to state also the starting mode-D.O.L. or VSD- for instance- and calculate the limited voltage drop. If you intend-for black start-to employ a Gas Turbine included a Diesel Generator it could be another problem. Other auxiliary facilities as Ash Handling, Coal Handling, and Desulphurizing Plant and so on could change the ST power level.

So, for an inexperienced engineer this is an exercise only.

thanx for urs replies and i'll see how to find an experienced person/team...as per 7anoter4 420 kV switchyard scheme is: 2 Bus and Transfer Bus scheme (2000A, 1000A respectively;40 kA) 11 Bays in total: 2 for GTs, 2 For STs, 4 lines, 1 Buscoupler, 1 Transfer coupler and 1 Spare. For motors BFP rating is 9.5 MW,11 kV,562/4.5 In; 2x4.2 MW,11 kV,266/5.9 ID Fans fed from unit bus; 2x3.65 MW,11 kV 217/6In PA fans fed from unit bus; 2x1.4 MW,3.3 kV,289/5.5In FD Fans again fed from unit bus; 4x2.150 MW,11 kV CW pumps and CHP switchgears all fed from Station bus... all the aforementioned motors r DOL started....i'd like to say that right now i don've any load list of unit n station buses n in absence of that i can't approximate the load sum of buses.

But given said that, hypothetically if i've unit bus load and station bus load then how can i reach to GT rating, i again guess that with unit bus n station bus loads one would be able to select UAT n ST rating...if i'm wrong then please correct me if u can spare the time on mines post

I am sorry. I cannot design the Power Station. First of all there is not enough data. Second, it is a problem where are involved many engineering domains: electrical, mechanical, civil design and so on. As I already said a minimum of 10-15 engineers has to works a few weeks in order to produce a suitable one line diagram at 420 ,20,11 and 3.3 kV, a workable general lay-out and so on.At first glance only [my opinion only]:GT=700 MVA [17%]; UAT1+UAT2=20 MVA/11 KV +20 MVA/3.3 KV; ST=50 MVA [14%]You would need a Gas Turbine of 20 -30 MW and a DG of 2000 HP [at least].You will need [probably] a 5000 sqr.m for the main building and facilities. You have to check voltage drops,calculate the short-circuit currents, the load flow and so on.

At a minimum "We" need to hire a competent Electrical Power Engineer who has many years of experience doing what you have been asked to do. From my experience the design and engineering of the generating station main and auxiliary power transformers involves much more than just a list of name plate ratings and includes a lot of questions and requirements that most electrical engineers wouldn't even know to ask about.

If you are passing yourself off as a consulting engineer the only ethical thing to do is to inform your client that this work is out of your area of expertise. There is at least 200 manhours of dedicated study required to this properly, double or triple that if you want to pay for someone's learning curve, anything less will result in your posting questions such as "....Help, my TG just tripped and I don't know why..." that are seen on this site and others like it.

Detailed engineering has to be done then we have to do the diemensioning of the devices We can do it for cost