STATION TRANSFORMER

1.0.   PURPOSE

            The purpose of this calculation is to determine the capacity of Station Transformer for  1 x 660 MW   CIREBON Coal Fired Steam Power Plant.

2.0.   SUMMARY

2.1 One Station Transformer is provided for the start up of the plant and after that UAT will cater    plant load.

2.2 The result of calculation is summarized as follows.

STATION TRANSFORMER

Cooling                                  :  ONAN/ONAF

Winding  Temp. rise             :  60º C

Winding                                 :  3 phase 3 winding

Capacity                                 :  60/30/30 MVA

Note 1 : The above XFMR Capacity is based on the 45ºC Amb. Temp.

3.0.   REFERENCE

3.1 Cirebon power plant load data

3.2 IEC 60076-1

3.3 IEC 60076-2

3.4 ANSI C57.91

4.0.   DESIGN CRITERIA

4.1 Design ambient temperature is 45º C

4.2 Transformer is three phase three winding having the star-star-star connection, YNyn0yn0,   ONAN/ONAF, 150/11.5/11.5 KV.

5.0.   ASSUMPTION

5.1 All motor loads having the stand-by operation mode has been excluded in this calculation.

            5.2 Transformer data

Description                                                  

a. Type                       : 3 phase, 3 winding, 50Hz

b. Rated                     : voltage150/11.5/11.5 KV

6.0.   CALCULATION

Inputs:

Total Load on one bus of 11kV System in KW  = 22158.00 KW

Power factor                                                         = 0.85

Total Load on 11kV System in KVA ( L )          = 26068.24 KVA

No Load Voltage (Vn)                                          = 11.5 kV

Full Load rated voltage (Vr)                                = 11 kV

Full load losses (Wf1)                                         = 294.00 KW  at  60 MVA

Actual KVA Load on Transformer (Wa)            = 26068.24 KVA

Load Calculation for Power Transfomer:

Considering 10% margin, KVA load                   = L x 1.1

                                                                                = 28675.06

So the selected Transformer size                        = 30000 KVA

7.0.   ENCLOSURE

          7.1 Load Summary for MV Switchgear

          7.2 Load Summary for MCC