ARUN III HEP (4x225 MW), NEPALChapter of Generator Transformer (Section-4)Sr. No.Clause no.SJVNs CommentsSJVN reply on replies of WAPCOS dated 30.01.2015

1.4.1.2Maximum allowable size and weight limit of package that can be transported is mentioned as 14mX5mX4m and 100 tonne.Criteria for choosing this limit may be provided. Ok

2.4.2.4The capacity of EOT crane is mentioned as 90T whereas in DPR the capacity of crane for transformer cavern is mentioned as 100T. This may be clarifiedAgreed and the capacity should be in line with EOT Crane chapter

3.4.3Short circuit withstand capacity mention is 63kA where as it is 40kA in case of Switchyard. This may be clarified.WAPCOSs reply awaited

4. 4.5.1Noise level limit 85dB limit has specified. Relevant NEMA standard publication no. TR1 as mentioned may be provided.Relevant pages of Nema standard may be supplied by WAPCOS.

5.4.8.2The criteria for choosing magnetizing characteristics upto 1.8 p.u. may be given. Agreed

6.4.5.8As per this clause Transformers shall be capable of operating at full load for 10 minutes after failure of the oil or water circulating system with the calculated winding hotspot temperature not exceeding 1400C. Whereas in CBIP Manual this temperature is mentioned as 1500C. This may be clarified.Agreed

7.4.9.3As per this clause The penalties per KW for the excess of no load losses, load losses and auxiliary losses over the guaranteed values will be calculated at the rate of Rs 3.50 lakhs; Rs 3.20 & Rs 3.50 respectively. The calculation for capitalisation of losses to be provided for mentioned rates.Calculations for arriving on such a rate is to be provided.

8.4.10.1The criteria for choosing 300mm2 XLPE cable for connecting HV terminals of Transformers with Air Insulated Switchgear may be provided. Cable sizing calculations may be provided.Calculations to be provided for choosing cable size.

9.4.13.1.1The criteria / supporting document for choosing tank strength to withstand without distortion pressure of 0.35 Kg/cm2 with oil at operating level may be provided.Agreed

10.4.13.3.5,4.13.3.7, 4.13.3.9, 4.13.4The supporting documents / calculations for various values / parameters chosen in the clauses may be provided. WAPCOSs reply awaited

11.4.15.1Calculations for minimum knee point voltage (Vk) for NCT may be provided.Ok, Table at 4.15.1 may be modified accordingly.

12. 4.30.6In this clause Special tests have been indicated as optional. This may be clarified.These tests are not optional and they are required to be carried out on one transformer. Additionally SFRA test and FDS test are required to be carried out as special test and site test. TS to be modified accordingly.

13.SLDCalculations for all CTs used for GT shall be provided.WAPCOSs reply awaited

14.SLDDifferential protection shown in neutral side of GT may be reviewed.ok, SLD to be modified accordingly.

Replies of clause 4.40( Station and auxiliary transformers) not submitted by WAPCOS