I.€¦ · CFVV type of voltage variation in view of design ... earthing/auxiliary transformer & 11kV neutral side indicated 500A, 10Sec, neutral ground resister

2 400/220kV Isinya, Athi River and Nairobi North substation extensions

This tender addendum and clarification forms part of the Request for Proposal and Contract documents, and modifies them as follows:

I. CLARIFICATIONS

S.No. Clause/Paragraph/Item No. Clarification/Query Response

4 Isinya Substation

Tariff metering panel is Indiacted in the single line diagram

& Technical SPecification; Whereas price schedule doesn't

call for supply of tariff metering panel. please clarify.

Refer to addendum for additional item on tariff

metering system.

5 Isinya Substation

We have been informed that Isinya substation is under

construction by IBERDROLA (contract 2013)and we

presume that the control system & busbar protection for

220kV system are supplied by M/s GE, Spain.

the Technical specification calls for supply of 4 nos of

220kV side transformer protection panel for

400/220kV transformer bay under this contract.

Please note that the scope calss for the existing two

numbers of 220kV line bay shall be replaced by 2 nos

of transformer bay. However the existing 220kV Line

protection panel shall be decommissioned and shall

be replaced with with New 220kV transformer

protection panel to be supplied under this contract

and two numbders of New transformer bays are

proposed bay dia -3. Hence we request you to provide

the following details.

a) Existing two numbers of 220kV line bay shall be

replaced by 2 nos of Power transformer bay having

This will be finalized with KETRACO on contract award because the current protection equipment general



BCU and breaker failure relay protection. Hence

please confirm whether the existing BCU & breaker

failure relay shall be retained or bidder has to supply

ne one. Please clarify

b) Please confirm wherthe bidder has to match the

existing the relay type/make for BCU and CB failure

relay for Proposed two number 220kV transformer

bay (proposed dia -3).

If bidder has to match with existing relay then please

provide make, country of origin and type of existing

relay

c) Please provide the existing 220kV busbar

protection relay make/type

d) Please Confirm availability of bay module unit of

existing low impedance busbar protection for

proposed 220kV dia -3 under this contarct .

e) Provide existing 220kV, SCADA make/type and

manufacturer country.

arrangement and layout is not known at this stage. Information currently unavailable, as such will be discussed on contract award Details unknown at this stage Details unknown at this stage Details unknown at this stage

6

Isinya Substation

The technical Data sheet of 200MVA Auto transformer calls for flux voltage variation as VFVV.type of is required for OLTC. However please clarify that Bidder can propose CFVV type of voltage variation in view of design feasibility and ease point of view. Also reputable OLTC manufacturer have not supplied tap changer for such arrangement.Kindly advise

Refer to addendum for an update to 400/220kV power transformer type of flux variation. Bidders are reminded to follow Section IV item 14.1 Note 1 which states that, “the tap changer shall be located at the LV line-end neutral point, unless this conflicts with other transformers nearby.”



7

Isinya Substation

Price schedule for Isinya substation, item no.8.15 calls for supply of Joint Bays, pits for link boxes, including excavation, shuttering, concrete works according to specification and reinstatement is 1Lot; Whereas in the same price schedule, item no. 8.4, “Sectionalising joint including all necessary material connections and accessories, quantity is zero. Hence please clarify requirement of link box for joint bays.

The short length of the 220kV cable suggests that joints will not be required. Items 8.15 are generic, in this instance they represent cable termination bays.

8

Isinya Substation

As per Guaranteed Technical Particulars (GTP), item no.5,

current transformer, number of core calls for 4 cores for

400kV & 220kV current Trasformers. Whereas tender

protection Single Line Diagram indicated 5 cores for 22kV

CT & 6 cores for 400kV CT.

Hence please clarify the requirement

Refer to protection SLD for the number of cores required, however Guaranteed technical particulars (GTP) core numbers are only indicative

9

Isinya Substation

As per Protection Single Line Diagram (220kV, transformer

Protection SLD), Drawing#PB-KET-2012-P-253, Rev-P1, has

indicated 11/0.415kV, 500kVA, earthing/auxiliary

transformer & 11kV neutral side indicated 500A, 10Sec,

neutral ground resister (NGR) Whereas price schedulefor

Isiniya substation does not calls for supply of neutral

ground resister (NGR).

Hence please clarify.

Refer to addendum for updates to various issued documents relating to installation of neutral earthing resistors

10 Nairobi North Substation:

We request you to provide CT parameter details of existing

220kV and 66kV busbar protection core.

The details are not available at the moment however this information can easily be gathered during the pre-bid site visit




Scope of work calls for supply of one number 220/66kV, 90

MVA transformer. Since Single line diagram and switchyard

layout indicated two number, existing 220/66kV, 90MVA

transformer. In this condition please confirm the following

details.

a) Confirm parallel operation is whether required or not.

b) If parallel operation is required then Please provide

number of taps and % of impedance, Vector group and

type/make of AVR relay of existing transformer.

c) Confirm philosophy of parallel operation at a time

whether two transformer (two transformer parallel,

another one is standby) or three transformer.

d) Provide existing transformer name plate details.

Details of parallel operation of transformers have not been agreed as yet with KETRACO, however since all the transformers will be connected to the same busbar, common practice dictates that some form of control will be required. This will be discussed with KETRACO on contract award.


We request you to provide the existing 220kV busbar

protection make/type of relay.

The details are not available at the moment however this information can easily be gathered during the pre-bid site visit


As per price schedule SCS calls for Hardware and software

necessary to control and monitor the substation extension

and modification -1 lot. Whereas tender protection single

line diagram is not indicated SCS system. Hence please

clarify the requirement of substation control system.

The requirements of this contract are given in Kenya System Reinforcement bid document Section VI Employer’s requirements item 8.2.1.2 Items in the Price schedules are generic and therefore do not specifically refer to SCS.

14

Athi River

We request you to confirm the operation of capacitor bank

whether manually operated or Automatic (APFC –

Automatic power factor correction) for 220kV, 200MVAr

capacitor bank.

Manual operation



15

Athi River

We request you to provide existing 220kV busbar

protection make/type of relay and confirm availability of

bay module unit of existing low impedance busbar

protection for proposed 220kV capacitor bank bay.

This is a substation currently under construction for which detailed design is still ongoing. The details will be provided to the successful bidder during contract execution.

16

Power Transformer

According to the Qualification requirement, it is not clear

by "Type Tests", if the client requires Short circuit test as

well. Because the witness is valid as well, and short circuit

tests cannot be witnessed at vendor's place as it is not

possible to carry out this test at any manufacturer's lab

anywhere in the world.

As per the technical specification Clause 14.7.4 Point # 4,

vendor can submit the short circuit calculations instead of

short circuit Test.

Please clarify that can we propose the Transformer

manufacturer who has carried all the type test at

independant Test laboratory expcept Short circuit test in

the similar or higher rated transformer and submit only

short cir5cuit calculations shall qualify

Kindly confirm if it is valid and qualify

Confirmed, all tests and calculations shall comply with IEC 60076-5

17

Commercial

Mode of payment:

1. We presume that the payments for the off shore portion

will be made thro a confirmed letter of credit. Furthermore

the cost of opening of L.C. will be borne by the employer.

Please clarify.

2. We presume that the payments for the On-shore portion

will be made thro a DIrect Telegraphic Transfer. all th

Refer to TAC 2 S.No. 2 and 3



ebanking charges will be borne by the employer. Please

clarify.

15

Commercial

Bid Security:

Please clarify if the bid security (bank guarantee) issued

from a reputable bank from bidders country is acceptable.

No. The bid security must be issued from a Kenyan bank.

16

Commercial

While referring the ITB clause 17.7, we found that Bidder

shall quote their price in Adjustable basis. Please note that

most of the equipment manufacturers are not ready to

offer their price in Adjustable price basis due to their

various complications. Also it will be a convenient practice

to quote the price in firm basis. Hence we request you to

amend the ITB clause 17.7 as per the following

“The Prices quoted by the Bidder shall be: “Firm“ instead

of “Adjustable”

Ammend ITB datasheet clause 17.7 to read as follows: The Prices quoted by the Bidder shall be: Fixed

17

Commercial

Please clarify that Customs/Import duties and Local taxes

(VAT) and other taxes for goods imported in to the

employer's country are exempted for this project.

Please also clarify that whether bidder has to include VAT

& other local taxes for materials supplied from Employer's

country (On-shore), Local Transportation, Civil &

Installations services in their prices or Not .

Kindly clarify

The Contractor is exempt from all taxes and duties. However withholding tax and levies such as RDL and MSL are not exempt and the Contractor should familiarize himself with all new levies imposed since January 2013 as these are not exempt.

8

400/220kV Isinya, Athi River and Nairobi North substation extensions

II. ADDENDUM The following Addendums to Kenya Reinforcement Bid Document are as follows:

Schedules of technical section 400kV open terminal equipment after item 10 400kV Surge arresters and 220kV open terminal equipment after item 10 220kV surge arresters add the following table:

OPEN TERMINAL SWITCHGEAR

DATA

Required Offered

11. COMBINED INSTRUMENT TRANSFORMERS

11.1. Manufacturer & Place of manufacturing

11.2. Type

Post

11.3. Standards

IEC 60044-3, 61869

11.4. Rated continuous thermal current at 40oC Rated extended

primary current

11.5. Current transformers

Refer to Tender

Drawings

- Number of cores

- Rated extended primary current 120%

- Ratio (TR – turns ratio)

I core A

II core A

- Class

I core

II core

- Knee point voltage (Ek)

I core V

9


II core V

- Exciting current (IE) at Ek

I core mA

II core mA

- Rated output (burden to be 25-100% rated

burden)

I core VA

II core VA

Total mass of single phase current transformer

complete

kg

11.6

Voltage transformer

- Number of secondaries

- Maximum permissible partial discharge level

Um

- Maximum permissible partial discharge level

1.2Um /3

- Method of suppressing ferroresonance

pC

pC

Refer to Tender

Drawings

10

5

- Ratio (TR – turns ratio)

- Voltage factor, PU – BS EN 61869

1.5PU, 30 secs

11.7

- Rated accuracy class

I secondary

II secondary

- Rated output (burden to be 25-100% rated burden)

I secondary VA

II secondary

VA

Mass of single phase combined unit kg

VA

VA

kg

Item 4.4.10 Site tests, shall be edited as follows: “Partial discharge measurements and records” shall be removed from Scope of works

10


Schedule of technical information 400/220kV Power Transformers (AIS-AIS) : “Maximum noise level (NEMA TR1 – 5dB(A)) 82dB(A)” shall be updated to “Maximum noise level (NEMA TR1 – 5dB(A)) 83dB(A)”

Section VI the following shall be added after Item 15.4:

15.5 Neutral Earthing Resistor

Earthing resistors shall be of stainless steel metal grid type, be drip-proof and suitable for outdoor service on 11kV three phase systems as appropriate. The resistors shall be rated for 10 seconds and the current ratings and ohmic value shall be as shown in the drawings in Appendix A. The continuous current ratings shall be indicated in the Technical Schedules based on IEC and site ambient conditions. The neutral earthing arrangement shall be as per requirement indicated in drawings (Appendix A).

Neutral earthing resistors shall be designed, manufactured and tested to IEEE 32. Equipment shall also comply with IEC 61000-6-3.

The framework of neutral earthing resistor shall be of galvanized steel and totally enclosed by galvanized expanded metal or perforated sheeting. The enclosure shall take into account the heating effects of the resistors being designed to be maintenance free for at least 30 years. The grids shall be of stainless steel alloy and be adequately supported on steel rods and porcelain insulators and be designed to withstand the currents flowing under fault conditions. Adequate insulating barriers shall be provided to prevent internal flashover.

The resistor shall be complete with lifting and jacking lugs, access manhole, holding down bolts or clamps, earth terminals, connectors and connections and bushings suitable for the system phase to neutral voltage.

The specified resistance is to be that at the design ambient temperature and it shall be capable of passing the specified current for 10 seconds with a maximum temperature rise as stated in the relevant section in the Schedule of requirements. The coefficient of resistance with respect to operating temperature shall also be stated.

The protection class for neutral earthing resistors shall be IP23 for indoor use and IP54 for the NERs to be used outdoors. The specific requirement of protection class shall be as detailed in the technical schedules in line with IEC 60529 requirements.

15.6 Neutral earthing resistor Tests

All neutral earthing resistors shall be subjected to routine tests according to the relevant approved specifications in the presence of KETRACO representatives at the manufacturer’s works.

The supplier shall make provision in his offer to bear all costs that are incurred in carrying out these tests to the satisfaction of KETRACO. However, the costs towards travel, accommodation etc of KETRACO representatives shall not be included in the quoted price.

Section IV Bidding Forms, Schedules of technical information; 400/220kV Power transformers (AIS-AIS) Item: “Type of flux V.F.V.V” shall be changed to “Type of flux C.F.V.V”

Section IV the following shall be added to Schedules of technical information 11/0.415kV; 500kVA earthing/ auxiliary transformers (CAF-CAF) after Item 1.59:

11


O. NEUTRAL EARTHING RESISTOR UNIT DATA

Required Offered

1.1. Manufacturer

1.2. Type

1.3. Standards IEEE 32,

IEC61000-6-3

1.4. Rated voltage

kV 11

1.5. Rated fault current

A Refer to

drawings

1.6.

Continuous current A

1.7

1.8

1.9

1.10

1.11

Maximum operating time

Resistor material resistance cold

Temperature rise at rated voltage after 10 sec

Protection class

Installation: indoor/ outdoor

sec

Ohm

Deg C

10

1000

12


Section VI Employer’s requirements, Appendix A – Bid drawings after Overhead line drawings the following section shall be added

Cable drawings

63593A/PBP/L/0013 – Typical 220kV double circuit cable trench layout

63593A/PBP/L/0014 –Typical 220kV double circuit over crossing services cable trench layout

63593A/PBP/L/0015 – Typical 220kV cable trench layout for undercrossing of gas/ water service

63593A/PBP/L/0016 – Typical 220kV cable trench layout for road crossing

The following items in Annex 1 Price Schedules shall be edited as follows:

Schedule No 1 after item 10.47 shall be added “Neutral earthing resistors foundation 4 No”

Schedule No 1 after item 11.6 shall be added “Neutral earthing resistors 4 No”

Schedule No 1 after item 13.10 shall be added “Tariff metering system 1 Lot”

Documents

I.€¦ · CFVV type of voltage variation in view of design ... earthing/auxiliary transformer & 11kV neutral side indicated 500A, 10Sec, neutral ground resister