Section 2: Technical Specification for Turbines, Governors, Main Inlet Valves and associated auxiliaries

Sr.No. Clause Comments of SJVN Replies after receipt from WAPCOS

1. 2.1.1&

2.23 (D) to (H)

Separate TS sections have been

envisaged for Butter fly valve, cooling

water system, LP air system and

Drainage & Dewatering system. Even

then items of above system have been

incorporated in this scope. Contradiction

shall be clarified.

Wapcos has agreed with SJVN,

thereby accepted

2. 2.2.1.3 Selection of Turbine capacity as

225000.0 KW at a design head of 287.0m

may be clarified. In our opinion, turbine

output has to be more that above value at

this head.

Accepted

3. 2.2.2.1 Supporting documents for selecting

inertia constant (H) as 4 MW/MVA shall

be submitted.

Accepted

4. 2.2.2.2 The figure of 356 does not have any

unit, clarification & supporting document

shall be submitted in this regard.

Wapcos has submitted the

maximum momentary pressure as

387mWC. In our understanding, it

shall be 356mWC (879.75-

525=355mWC). Please clarify.

5. 2.2.2.6 The supporting document for selecting

minimum weighted average efficiency as

94% shall be submitted.

Not accepted. As per CEA

guideline for Best practices “The

minimum weighted average

efficiency obtainable for Reaction

turbine is 95%”.

6. 2.2.2.7 (III) (b) & (c)

The 343.43m3/sec is rated discharge

corresponding to rated output ( 900MW)

of plant as per DPR whereas in this

clause it has been considered as running

of 4 machine with 10% overload at FRL.

The contradiction shall be clarified.

Not agreed. The comment was that

with 10% overload, the discharge

would increase. The increased

discharge should be specified here.

7. 2.2.2.7 (III) (c) It is not understood how tail race water

level corresponding to 466.0 m3 will be

lower than 343.43 m3 and from where

this discharge of 466.0 m3 has been

considered.

The clarification is needed for above.

Ok. Row may be deleted.

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8. 2.2.2.8 Purpose of Incorporating this clause shall

be clarified & justified as power house

dimensioning and equipment layout

planning has been carried out with

machine speed of 250 RPM only.

Ok. The clause may be deleted.

9. 2.2.3 Approved DPR envisaged the hard

coating for susceptible under water

components whereas no such provision is

made in the specification. The reason for

same shall be provided.

No hard coating has been proposed

in this clause. Kindly check the

same and include the details of hard

coating in the clause.

10. 2.2.3.1 Section-I does not cover any details in

respect of Petrographic analysis and

chemical analysis of water as referred in

this clause. Same shall be clarified.

Ok. Please include the same in the

Section-I

11. 2.2.4.1 & 2.2.4.2 (a)

If turbine give output of 228426.40kW at

a design head of 287.0 m at 100% Guide

vane opening then how Turbine will

produce 110% output . Same shall be

clarify.

Not agreed. The clause may be

modified as following:

The following turbine outputs and

efficiencies shall be guaranteed by

the bidders in their bids

a) 228426.40kW output at the

design net head of 287 m and

less than 100% guide vane

opening for 100% generator

output.

b) One hundred and ten percent

(110%) output of generator at

100% (full) guide vane opening

at the minimum (rated) head.

c) Turbine efficiencies at 110%,

100%, 90%, 80%, 75% and

70% of the rated turbine

outputs at various listed net

heads in the specified working

head range. At lower

percentage of rated outputs viz

from 50% to 20% the value of

expected efficiencies shall be

stated in the bids.

12. 2.2.4.2 Criteria for selecting 2% as difference in Relevant clause of other projects

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efficiency between maximum efficiency

and that at rated output & rated head

shall be submitted..

may be submitted along with.

13. 2.2.4.3 (1) Criteria (standard, norms, benchmarks etc.) for choosing this formula for weighted average efficiency shall be submitted.

Accepted.

14. 2.2.4.4 (4) Supporting documents for choosing penalties values specified in clause for shortfall of Output and weighted average efficiency shall be submitted.

Accepted

15. 2.2.4.4 (7) Criteria for selecting rejection limit value as 2% or more needs to be supplied.

Relevant clause of other projects may be submitted along with.

16. 2.2.5.1 Safe operating zone for machine in the cavitation as well as non cavitation zone shall be clearly specified in the specification.

It is requested to supply a copy of IEC 60194

17. 2.2.5.3 Supporting documents for limiting the speed rise limit of 45% shall be provided.

Please cross check the relevant documents since as per IS 12837, the speed rise limit has been set from 35 % to 55 %.

18. 2.2.5.4 (1) Seismic force considered in Section –I as

per clause 1.8.7.1 are 0.33g for

Horizontal and 0.22g for Vertical whereas

it is different as per this clause. The

contradiction of values shall be clarified.

Ok. The base document may also

be specified).

19. 2.2.6.8 (3) Justification for incorporating this clause may be clarified with benchmark documents or other guideline documents.

Not agreed. Please submit the relevant documents as per latest guidelines issued by Govt. of India

20. 2.3.2.4 & 2.3.2.5

Calculation document for considering static pressure as 320.0mWC and Transient pressure rise as 430.5 m shall be submitted.

Please submit the document for transient pressure rise of 430.5 cumecs

21. 2.3.6.1 Justification for selecting Materials, manufacturing method etc. for different component of Turbine shall be provided with their merits/demerits.

Supporting document not attached

22. 2.3.6.1.2 Analysis document with merit & demerits shall be provided for selecting material and manufacturing methodology for Runner so that suitability at Arun-III HEP shall be ensured.

Supporting document not attached

23. 2..4.13..1 Supporting documents for limiting the runaway speed test period as two (2) minutes shall be provided.

Not agreed. The period for runaway speed test has to be provided in the specification or minimum of CEA guidelines has to be adhered to.

24. 2.5.3.1 (i) Reason for selecting wicket gate closing time range from 0-20 seconds shall be supplied. It is understood that being a hydro-mechanical item closing of wicket gate in 0 seconds is impossible.

Range to be supplied along with supporting document.

25. 2.6.1.2 287.0m is design head for the machine, whereas static head corresponding to

Ok. To be incorporated in technical specification.

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FRL & M/c Centre line is higher (845-525 = 320m), Therefore, discrepancy in the value shall be clarified as it will impact the design of MIV.

26. 2.6.2 (A) (iii) to (ix)

Justification of calculations for selecting the listed parameters in this clause shall be provided.

Please the calculations along with the relevant documents for all the calculations for above values.

27. 2.6.2 (B) (i) Justification documents shall be submitted for selecting the design of MIV opening under differential pressure of 50%.

Kindly submit the supporting document along with relevant standard.

28. 2.6.2 (B) (i) & (ii)

Criteria (standard, norms, benchmarks etc.) for choosing opening and closing time range as 60-120 sec shall be submitted.

Kindly submit the supporting document along with relevant standard.

29. 2.6.2 (C) Section-I does not cover any such details as referred in this clause. Same shall be clarified.

Ok. Please include the same in the Section-I

30. 2.6.2 (D) Seismic force considered in Section –I as

per clause 1.8.7.1 are 0.33g for

Horizontal and 0.22g for Vertical whereas

it is different as per this clause. The

contradiction of values shall be clarified.

To be changed.

31. 2.6.5.1 (d) The calculation in respect of maximum hydrostatic pressure of 534mWC shall be submitted.

There is no clause 2.6.2.8. Kindly submit the calculations for the same.

32. 2.6.5.16 Justification for selecting Ultrasonic flow detector shall be provided as winter Kennedy type flow meter is also proposed in clause 2.9.1.

Both methods provide for flow measurement (one equipment to be provided only)

33. 2.7.1 Justification for selecting separate OPU system of Turbine and MIV shall be submitted

Not agreed. . Documents of similar project to be provided.

34. 2.7.7 The guide vane control through head is not considered in governor as per clause 2.5.3 whereas it has been described in this clause. Contradiction in this regard shall be clarified.

Ok. Same shall be incorporated.

35.2.14.1

The supporting document shall be submitted for proposing the various kind of test to be performed for Turbine equipment’s.

The question relates to the supporting documents for the necessity of tests to be included in the TS. Kindly provide the relevant supporting document.

36. 2.16 It is not clear from this clause whether Field acceptance test for performance and efficiency in respect of guaranteed figure to be performed on one unit or all unit. Same shall be clarified and elaborated.

Ok. Same shall be incorporated in the TS

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