Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
1 Lot C Nairobi East LVAC and DC - for the purpose of the tender the bidders
shall offer a new system covering the 400kV and 220kV.
Control System - the price schedule is clear, therefore
please offer as required.
2 1. Extension of HB1 and HB2 busbars are not in the
scope.
2. For the purpose of the tender bidders shall assume
Lamu construction (under the Power Plant scope) will
commence first prior to Lot C works.
3. Under this tender the bidders shall provide a new SCS
system for the entire substation
3 1. Garsen feeder is not in the scope, so please focus on
the required scope only.
2. Please focus on the required scope only.
3. No, please follow as required in the tender drawings
4. Revised SLD is uploaded in KETRACO website as
Addendum 03.
5. Available existing drawings are uploaded in KETRACO
website as Addendum 03.
6. Revised Layout is uploaded in KETRACO website as
Addendum 03.
7. Available existing drawings are uploaded in KETRACO
website as Addendum 03.
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
1 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
4 1. The technical specification is not a site specific
document and therefore site specific requirements are
detailed in the technical schedules.
2. For Lamu and Hindi the altitute shall be below 1000 m
3. (a) The specification is clear.
(b) Neutral Reactor is required.
(c) Please comply as required.
(d) Yes, correct.
(e) Refer to TAC 2 item no. 12.
5 TAC 1 Lamu It was stated as:
Lamu is not constructed,
therefore for tendering pupose
bidders may assume SCS is
installed.
Bidders shall offer for a new SCS as stated in item 2
under this TAC.
6 Clarification Lot
C Technical
List No.01
Q.No 35
There are discrepancies in the
dimensions of the plot area.
The plot co-ordinates received
from site visit for Nairobi East
substation has the dimension of
850 x 300 m .
As per pre-bid clarification reply it
is 1500 x 300m.
Please clarify which is right.
Please follow the diamensions provided in the
calrifications.
7 General Substation fencing/levelling shall
be done only for the area
required for substation platform
area including future feeders (as
per Specification) and not for the
complete 1500x300 m plot. No
scope of works like
fencing/levelling/landscaping/bus
h clearing is envisaged in the
unused/free area. Please
confirm.
Correct. No levelling, clearing, landscaping works
required outside substation fencing which are not used.
However boundary fencing would be required to cover the
whole land plot. Refer to bid drawings.
8 General Existing 220kV towers are meant
for LILO to Koma rock substation
as understood from site visit.
There is no scope of works
envisaged for the same. Please
confirm.
The LILO is under OHL Lot A work package.
2 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
9 General Please inform us the source and
destination substations
connected by the transmission
line towers located on the road
between Koma Rock and Nairobi
East substation for information.
Refer to bid drawings.
10 Clarification Lot
C Technical
List No.01
Q.No 60
Please clarify whether the neutral
earthing resistor rating shall be
1050 A for 30 sec or 500 A for 10
sec.
1050A for 10 secs. (Supersedes item no. 60 TAC 1)
11 General Please provide the plot co-
ordinates of Koma Rock
substation.
Please read TAC 1 and 2.
12 Clarification Lot
C Technical
List No.01
Q.No 55
As per clarification reply ,
Minimum capacity of tertiary
winding shall be 1/3 of main
winding capacity.
Hence, Main winding 3 ph
Capacity (Full cooling) - 300 MVA
Tertiary winding 3 ph capacity -
300/3 - 100 MVA
External loading - 0.5 MVA
Total capacity of tertiary winding
3 ph - 100.5 MVA
But as per transformer datasheet
, 70 MVA is given.
Please clarify final rating required
and update the datasheet.
Please read TAC 1 and 2.
13 General As the external loading of the
tertiary winding is 500 kVA , we
presume transformer tertiary
bushing shall be rated for the
same. Please confirm.
Please comply to IEC standard.
14 Remote end
scope of works -
Protection and
telecommunicat
ion
&
Clarification Lot
C Technical
List No.01
Sr.NO : 79
Nairobi East to 400kV Lamu -
1&2
(i)We presume that make and
type of 87L line Differential relay
at Nairobi East to 400kV Lamu -
1&2 lines can be assumed by the
contractor.
(ii)87L at Lamu SS shall be
matched by other end
contractor based on 87L relay at
Nairobi East SS.
Please confirm.
Please read TAC 1.
3 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
15 Remote end
scope of works -
Protection and
telecommunicat
ion
&
Clarification Lot
C Technical
List No.01
Sr.NO : 79
Nairobi East to 400kV Isniya -
1&2
(i)We presume that make and
type of 87L line differential relay
at Nairobi East to 400kV Isinya -
1&2 lines can be assumed by the
contractor.
(ii)87L at Isinya SS shall be
matched by other end
contractor based on 87L relay at
Nairobi East SS.
Please confirm.
Please read TAC 1.
16 Remote end
scope of works -
Protection and
telecommunicat
ion
&
Clarification Lot
C Technical
List No.01
Sr.NO : 79
Nairobi East to 220kV
Embakasi
(i)We presume that make and
type of 87L line differential relay
at Nairobi East to 220kV
Embakasi line can be assumed
by the contractor.
(ii)87L at Embakasi SS shall be
matched by other end
contractor based on 87L relay at
Nairobi East SS.
Please confirm.
Please read TAC 1.
17 Non-Clarity in
the Limit of
Scope of
"Extension of
220kV Busbar
Protection
System - Low
Impedance &
High
Impedance at
Komorock
Substation"
Specification :
Volume 2 of 2 ,
page 2 of 385 .
(Price schedule
item no. 2.17 &
4.6)
As per Specification page 2 of
385 "The new 220kV busbars
shall be joined to the existing
Koma Rock 220kV (owned by
KETRACO) busbars to form one
continuous 220kV busbar" .
Hence we presume that no
equipments (Disconnector, Earth
Switch, Circuit Breaker , CT) is to
be considered as a part of Bus
Interconnection at Nairobi East
end as per Lot-C Scope of
works.
Please refer to bid drawings and price schedules.
4 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
18 Non-Clarity in
the Limit of
Scope of
"Extension of
220kV Busbar
Protection
System - Low
Impedance &
High
Impedance at
Komorock
Substation"
(Price schedule
item no. 2.17 &
4.6)
As per Specification page 2 of
385 "The new 220kV busbars
shall be joined to the existing
Koma Rock 220kV (owned by
KETRACO) busbars to form one
continuous 220kV busbar" .
Hence we presume that no
equipments (Disconnector, Earth
Switch, Circuit Breaker , CT) is to
be considered as a part of Bus
Interconnection at Koma rock end
as per Lot-C Scope of works.
Repeated question as 17.
19 Non-Clarity in
the Limit of
Scope of
"Extension of
220kV Busbar
Protection
System - Low
Impedance &
High
Impedance at
Komorock
Substation"
(Price schedule
item no. 2.17 &
4.6)
Please provide 220kV
conceptional Busbar philosophy
required at Nairobi East SS end,
after the Busbar interconnections
between Nairobi East SS &
Komarock SS,.
Under this tender the bidders shall provide price for a new
busbar protection system covering:
a. Diameter 3 and 4 (under this scope)
b. Diameter 1 and 2 (constructed by others)
The scope shall include:
a. retrofittings of hardwares/relays into existing panels (of
Diameter 1 and 2) supplied by others.
b. multicore cables from bay marshalling kiosk to busbar
protection panel.
The 220kV Busbar Protection system supplied under this
tender shall be installed in Koma Rock 220/66kV
substation building/room constructed by others. Please
read the specifications for the philosophy required.
20 Non-Clarity in
the Limit of
Scope of
"Extension of
220kV Busbar
Protection
System - Low
Impedance &
High
Impedance at
Komorock
Substation"
(Price schedule
item no. 4.6)
CT parameters (core details, VA)
at Komarock SS (for providing
220kV Low Impedance & High
Impedance Busbar protection) is
required.
Please furnish the same.
Will be furnished upon contract award.
5 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
21 Non-Clarity in
the Limit of
Scope of
"Extension of
220kV Busbar
Protection
System - Low
Impedance &
High
Impedance at
Komorock
Substation"
(Price schedule
item no. 2.17 &
4.6)
Please provide approved Bus-
protection configuration -
Centralised or decentralised at
Koma Rock SS End for : Low
Impedance Bus Bar Protection
See item 19.
22 Non-Clarity in
the Limit of
Scope of
"Extension of
220kV Busbar
Protection
System - Low
Impedance &
High
Impedance at
Komorock
Substation"
(Price schedule
item no. 2.17 &
4.6)
We presume that Cable trench ,
power cable, control cables, FO
cables between Nairobi East SS
& Komarock SS is not part of Lot-
C Scope of works.
All works required for the 400kV and the newly extended
220kV shall be part of the scope.
23 General Please provide Scope matrix
between Lot C Scope of works &
Komarock SS - for 220kV Busbar
Extension.
Bidders shall provide this as part of the offer.
24 Nairobi East
SS Section J,
page 171 /
Lamu 400kV
Extn Section J,
page 170),
“As per Technical data sheets of
Power transformer (Nairobi East
SS Section J, page 171 / Lamu
400kV Extn Section J, page 170),
The OLTC shall be located at LV
line end with CFVV however as
per IEC 60076-8, Fig-7, Page no
25, OLTC at LV line end can be
achieved with two possible
configurations.
Configuration (a) : Voltage
variation at HV side.
Configuration (b): Voltage
variation at LV side.
Please confirm the required
configuration. ”
At the first instance the bidders shall comply to the
technical specifications, and followed by IEC or other
relevant standards where there are ambiguties.
6 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
25 General When Koma Rock substation is
going to be constructed by
others, we presume access road
to koma rock will also be
constructed by others and the
same access road can be used
for proposed Nairobi East
substation also. Please clarify
whether access road to be
provided in present scope or not.
Access road is part of Lot C scope and this was clearly
explained during the site visits.
26 PB-KET-2014-
L-104
As per the layout it is mentioned
as maximum sag should be less
than 5% of the span length. We
infer that this criteria should be
met only for conductor sag .
Please confirm.
Also, Please clarify at what
temperature and wind conditions
this criteria should be checked.
Please comply and carefully read the specifications and
bidders are expected to use thier technical know how to
offer solutions.
27 Section VI -
Technical
specification,
clause 3.4,
page 47 of 385
As per specification it is given as
" The use of bare, stranded,soft
drawn copper is preferred by
KETRACO." Hence we are
following the same and adopting
exothermic weld for the main mat
earth conductors and
compression type bolted joints for
the above ground earth
conductor. Please confirm.
Accepted but subject to approval during design review.
28 Price schedule As per mandatory spares BOQ in
price schedule , Item F, S.No
1,2,3,4, 400kV and 220kV current
transformer and capacitive
voltage transformer has to be
provided. But, which type and
with how many cores to be
provided is not mentioned.
Please mention the
corresponding price schedule
item number under 400kV and
220kV primary plant for which
spare is to be provided.
Please refer to revised price schedules in Addendum 03
(Lot C). It shall be cross referenced with the bid drawings.
7 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
29 Vol 2 of 2
Technical
Specifications
clause 4.3.1.3 -
Page 65 of 385
4.3.1 - Page 63
of 385
Price schedule
1 Item 1.3 ,1.4 ,
2.2 , 2.3
As per specification
The 400kV earthing switches
shall be mechanically individually
operated, therefore furnished with
one manual operator per phase
The 220kV earthing switches
shall be mechanically group
operated, therefore furnished with
one manual operator per three
phases.
As per specification
Earth switches shall be fitted with
power and manually operated
mechanisms.
As per price schedule,
Disconnector with integral
motorised earth switches.
Please clarify whether integral
motorised earth switches or
integral manual earth switches to
be provided with disconnector.
Shall be manual earth switch. Revised Price Schedule is
provided in Addendum 03.
30 Schedule 4
Item no 26.14
The control room size given in
price schedule is 42 x 30 m.
Please clarify whether the control
room can be optimised as per the
requirement or it should only be
of the size given in price
schedule.
The proposed building size is 60m x 22m, for the purpose
of the tender the bidders shall offer for the required size.
31 General Please provide the orientation of
the following 400kV and 220kV
line bays .
400kV
Nairobi East to Lamu
Nairobi East to Isinya
220kV
Nairobi East to Embakasi
Nairobi East to IBT 3
220/66/11kV 200MVA
Please refer to bid drawings.
32 General Please provide the building
layout.
- Store building layout
The bidders shall submit a proposed layout as part of their
offer for the required size.
8 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
33 KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
Lot C_Tech
Spec_Section
V, Clause
8.2.4.1,
400/220kV
Auto-
transformers
(400kV side), d.
400 kV HV
connections
protection.
400kV Line bay CT:
As per SLD, one stub protection
is required with 5 core CT.
As per specification, both 400kV
connections -1 with stub
protection 1 and 400kV
connections -2 protection with
stub protection 2 is required with
6 core CT.
Please confirm whether 5 core
CT(as per SLD)) or 6 core CT(as
per specification) to be
considered.
STUB protection is not duplicated and therefore one set of
protection relay and CT is suffcient as shown in the SLD.
The revised technical specification will uploaded as
adddendum.
34 KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
Lot C_Tech
Spec_Section
V, Clause
8.2.4.1,
400/220kV
Auto-
transformers
(400kV side), d.
400 kV HV
connections
protection.
400kV Bus CT:
As per SLD, one stub protection
is required with 4 core CT.
As per specification, both 400kV
connections -1 with stub
protection 1 and 400kV
connections -2 protection with
stub protection 2 is required with
5 core CT.
Please confirm whether the SLD
(4 core CT) or specification (5
core CT) to be considered.
See item 33.
35 KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
Lot C_Tech
Spec_Section
V, Clause
8.2.4.1,
400/220kV
Auto-
transformers
(400kV side), d.
400 kV HV
connections
protection.
400kV Tie CT:
As per SLD, one stub protection
is required with 2 core CT.
As per specification, both 400kV
connections -1 with stub
protection 1 and 400kV
connections -2 protection with
stub protection 2 is required with
3 core CT.
Please confirm whether the SLD
(2 core CT) or specification (3
core CT) to be considered.
See item 33.
9 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
36 KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
400kV shunt reactor bushing CT:
Please confirm whether the core
1: 87-1/64REF required is of type
class 5P20 or PX.
Class PX.
37 KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
220kV CT:
Since core 1 of CT shall be used
for stub protection, CT core 1
shall be of type "PX". Please
confirm.
Class PX.
38 KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
Lot C_Tech
Spec_Section
V, Clause
8.2.4.1,
400/220kV
Auto-
transformers
(400kV side), d.
400 kV HV
connections
protection.
Bushing CTs on HV side:
As per SLD, one stub protection
is required with 4 core CT.
As per specification, both 400kV
connections -1 with stub
protection 1 and 400kV
connections -2 protection with
stub protection 2 is required with
5 core CT.
Please confirm whether the SLD
(4 core CT) or specification (5
core CT) shall be considered.
See item 33.
39 KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
Lot C_Tech
Spec_Section
V, Clause
8.2.4.1,
400/220kV
Auto-
transformers
(400kV side), d.
400 kV HV
connections
protection.
Bushing CTs on LV side:
As per SLD, one stub protection
is required with 4 core CT.
As per specification, both 400kV
connections -1 with stub
protection 1 and 400kV
connections -2 protection with
stub protection 2 is required with
5 core CT.
Please confirm whether the SLD
(4-core CT) or specification (5-
core CT) to be considered.
See item 33.
10 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
40
KET-2014-D-
001_Nairobi
East 400kV
SLD &
Protection Rev
3
Price schedule
1 Item Nos : 3.4
Lot C_Tech
Spec_Section
V, Clause
8.2.4.1,
400/220kV
Auto-
transformers
(400kV side), d.
400 kV HV
connections
protection.
Bushing CTs on HV side:
As per SLD, CT is with 4 core.
core 1: 87-1/64 REF, Cl 5P20
core 2: BCU/POW
core 3:50/51
core 4:STUB
In order to meet the protection
requirement as per price
schedule and Specification,the
following is considered
core 1: 87-1/64 REF, Cl PX
core 2: BCU/POW
core 3:50/51
core 4:HV connections -1
core 5:HV connections -2
Please confirm whether 4-core
CT or 5-core CT is required.
See item 33.
41 Lot C_Tech
Spec_Section
V, Clause
8.2.2,
substation
optical cables
and termination
Please confirm whether the
OPGW termination block (TB) is
in Substation contractor scope or
in overhead line contractor
scope.
This shall be part of Overhead lines contractor scope.
42 General Please clarify whether pre-
insertion resistor is required for
the following line bays.
400kV
Nairobi East to Lamu
Nairobi East to Isinya
220kV
Nairobi East to Embakasi
No. Please read TAC 1 item 70.
43 Clarification Lot
C Technical
List No.01
Q.No 109 & 96
Response to Q.No 109 says
control room has space provision
to accommodate protection and
control panels.
Response to Q.No. 96 says new
control building 40 x 32 m has to
be constructed.
Please clarify which one to be
followed.
New building shall be provided as Q.No. 96.
11 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
44 Clarification Lot
C Technical
List No.01
Q.No 1
As per price schedule, 1 x 90
MVA three phase auto
transformer
As per datasheet , Three single
phase auto transformers.
Please clarify whether the
autotransformer is single phase
(90MVA) or three phase (90
MVA).
3 phase.
45 Clarification Lot
C Technical
List No.01
Q.No 60
Please clarify whether the neutral
earthing resistor rating shall be
1050 A for 30 sec or 500 A for 10
sec.
See item 10.
46 Cl.no 19.17.9,
Vol 2 of 2 Page
354 of 385
Galvanized steel elements
exposed to seawater spray, those
located in the seawater structures
and those in drainage sumps etc
shall be suitable for a Class C5
exposure as defined in BS EN
ISO 14713.
we presume same class is
appliccble for Lamu ie average
galvanization thickness is 115 µm
(micron).
Please confirm
Yes.
47 Clarification Lot
C Technical
List No.01
Q.No 55
As per clarification reply ,
Minimum capacity of tertiary
winding shall be 1/3 of main
winding capacity.
Hence, Main winding 3 ph
Capacity(Full cooling) - 90 MVA
Tertiary winding 3 ph capacity -
90/3 - 30 MVA
External loading - 0.5 MVA
Total capacity of tertiary winding
3 ph - 30.5 MVA
But as per transformer datasheet
, 70 MVA is given.
Please clarify and update the
datasheet.
See item 12.
48 General As the external loading of the
tertiary winding is 500 kVA , we
presume transformer tertiary
bushing shall be rated for the
same. Please confirm.
See item 13.
12 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
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Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
49 Price schedule
: LOT C - Lamu
400/220kV Ext,
Appendix.2
Item No: 3.1,
400kV line
feeder
protection
Item No: 5
SCS,Telecomm
unication &
Associated
Equipment.
400kV Line bays:
(i)Lamu - Nairobi East-1
(i)Lamu - Nairobi East-2
From the price schedule, we
understand that no line
protection panel and
telecommunication works are
applicable for Lamu-1 & Lamu-2
400kV line bays.
Please confirm.
Correct.
50 Price schedule
: LOT C - Lamu
400/220kV Ext,
Appendix.2
Item No: 5
SCS,Telecomm
unication &
Associated
Equipment.
220kV Line bay:
Lamu - Hindi
From the price schedule, we
presume that there is no
telecommunication work is for
Hindi 220kV line bay.
Please confirm.
Telecommunication work as specified in price schedule
item 5.5.
51 Clarification Lot
C Technical
List No.01
Q.No 1
As it is an extension substation ,
we don’t anticipate any of the
following items in present scope.
Item 26.8 Substation perimeter
fence including security
Item 26.9 Plot perimeter fence
Item 26.13 Substation
gatehouseItem
26.12 Substation
compound/perimeter lighting
26.14 Substation control / relay
buildingItem
26.17 Sewage SystemItem
26.18 CarparkItem
31.6 Single Unit staff houseItem
31.7 Double Unit staff houseItem
31.9 Access road outside the sub
stationand also, for the items that
are not listed here , we assume
that we only conduct the works
related to the 400/220kV
transformer and the 400kV shunt
reactors bays.
Please re-check and confirm,
Please read TAC 1.
13 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
52 (Lamu 400kV
Extn Section J,
page 170)
“As per Technical data sheets of
Power transformer (Lamu 400kV
Extn Section J, page 170), The
OLTC shall be located at LV line
end with CFVV however as per
IEC 60076-8, Fig-7, Page no 25,
OLTC at LV line end can be
achieved with two possible
configurations.
Configuration (a) : Voltage
variation at HV side.
Configuration (b): Voltage
variation at LV side.
Please confirm the required
configuration. ”
See item no. 24.
53 Section VI -
Technical
specification,
clause 3.4,
page 47 of 385
As per specification it is given as
" The use of bare, stranded,soft
drawn copper is preferred by
KETRACO." Hence we are
following the same and adopting
exothermic weld for the main mat
earth conductors and
compression type bolted joints for
the above ground earth
conductor. Please confirm.
See item 27.
54 Vol 2 of 2
Technical
Specifications
clause 4.3.1.3 -
Page 65 of 385
4.3.1 - Page 63
of 385
Price schedule
1 Item 1.3 ,1.4 ,
2.3
As per specification
The 400kV earthing switches
shall be mechanically individually
operated, therefore furnished with
one manual operator per phase
The 220kV earthing switches
shall be mechanically group
operated, therefore furnished with
one manual operator per three
phases.
As per specification
Earth switches shall be fitted with
power and manually operated
mechanisms.
As per price schedule,
Disconnector with integral
motorised earth switches.
Please clarify whether integral
motorised earth switches or
integral manual earth switches to
be provided with disconnector.
See item 29.
14 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
55 Lot C_Tech
Spec_Section
V, Clause
8.2.2,
substation
optical cables
and termination
Please confirm whether the
OPGW termination block (TB) is
in Substation contractor scope or
in overhead line contractor
scope.
This shall be part of Overhead lines contractor scope.
56 Cl.no 19.17.9,
Vol 2 of 2 Page
354 of 385
Galvanized steel elements
exposed to seawater spray, those
located in the seawater structures
and those in drainage sumps etc
shall be suitable for a Class C5
exposure as defined in BS EN
ISO 14713.
we presume same class is
appliccble for hindi SS ie average
galvanization thickness is 115 µm
(micron).
Please confirm.
Yes.
57 Price schedule
: LOT C - Hindi
220kV Ext,
Appendix.D.3
Item No: 5
SCS,Telecomm
unication &
Associated
Equipment.
220kV Line bay:
(i)Hindi - Lamu
From the price schedule, we
presume that there is no
telecommunication work is
applicable for lamu 220kV line
bay.
Please confirm.
See item 50.
58 General As per site visit , the distance
between Hindi and Lamu
substation is 25km but as per
specification, it is 20km. Please
clarify which one to be followed.
Distance by road may differ the distance taken by the line
route.
59 Section VI -
Technical
specification,
clause 3.4,
page 47 of 385
As per specification it is given as
" The use of bare, stranded, soft
drawn copper is preferred by
KETRACO." Hence we are
following the same and adopting
exothermic weld for the main mat
earth conductors and
compression type bolted joints for
the above ground earth
conductor. Please confirm.
See item no. 27.
60 General Please provide the orientation of
the proposed 220kV extension
line bay
from Lamu to Hindi
Please refer to bid drawings.
15 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
61 Vol 2 of 2
Technical
Specifications
clause 4.3.1.3 -
Page 65 of 385
4.3.1 - Page 63
of 385
Price schedule
1 Item 2.2 , 2.3
As per specification
The 400kV earthing switches
shall be mechanically individually
operated, therefore furnished with
one manual operator per phase
The 220kV earthing switches
shall be mechanically group
operated, therefore furnished with
one manual operator per three
phases.
As per specification
Earth switches shall be fitted with
power and manually operated
mechanisms.
As per price schedule,
Disconnector with integral
motorized earth switches.
Please clarify whether integral
motorized earth switches or
integral manual earth switches to
be provided with disconnector.
See item no 29.
62 General Please provide the existing
busbar and line bay
conductor/tube details so as to
comply with the same for
extension bay also.
Existing drawings for Hindi is provided in the Addendum
No. 3 (Lot C).
63 General Please provide the existing
outdoor luminaires details so as
to comply with the same for
extension bay also.
Please refer to the technical specifications and it is
expected the bidders to take advantange of the site visits
to understand the existing site conditions.
64 General Please provide the overall layout.
- Existing drainage layout and
section
Please refer to Addendum 03 (Lot C)
The contractors shall survey and design the drainage
layout and section during the implementation stage
65 General Kindly provide the Finished
ground level (FGL) of the existing
substation for maintain the same
level for the extension area
Bidders shall assume the most practical FGL as per the
site visit
66 Lot C_Tech
Spec_Section
V, Clause
8.2.2,
substation
optical cables
and termination
Please confirm whether the
OPGW termination block (TB) is
in Substation contractor scope or
in overhead line contractor
scope.
This shall be part of Overhead lines contractor scope.
67 Where possible these details are provided in the
addendums.
16 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
68 First part of the question is answered in TAC 1.
Appendix C.1, C.2 and C.3 should read as follows:
1. 300MVA, 400/220/11kV for Nairobi East
2. 90MVA, 400/220/11kV for Lamu
3. No requirements at Hindi
69 See read TAC 1.
Technical Specifications , section 7.1 paragraph 1,
Bidders are expected to carry out insulation studies which
will produce the required surge arrester characteristics.
For the tendering purpose the bidders shall use MCOV of
289kV and with a TOV of 1.6pu. The actual TOV value is
subject to the outcome of the insulation studies which will
be determined during the design review.
70 TAC Item No. 86 It was stated as follows:
No. Stub Protection is for the Tie
Bus. Stub Protection
shall be used for OHL bay while
HVC shall be used in
Transformer bays.
STUB protection is the same as Connections Protection.
71 It is provided in Section G of the Technical Data sheet.
72 Please refer to shunt reactor specifications and technical
data schedules. The bidders are also advised to refer to
the relevant IEC documents where applicable.
73 Please read TAC 1, TAC 2 and Addendum 03 (Lot C)
17 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
74 In the bidding document, Clause
11.3.2.3, volume 2 of 2, the
110kV battery chargers has been
defined to be thyristor controlled
devices, but after contact with
some manufacturers with good
reputation, we found that the
thyristor controlled devices has
been out of production due to
technology improvement. now
most of the battery chargers are
high-frequency switch type. so
we advise to use the the high-
frequency switch type instead of
the thysistor controlled type.
Please comply as required in the specifications.
75 Please clarify the contradiction:
According to item No.85 of TAC-
2, "Hindi is installed with SCS.”
But in the attached drawings of
TAC-2, there is a "RTU560A" in
the drawings "SCADA
ARCHITECTURE" and "SCADA
PANEL FRONT
ARRANGEMENT DIAGRAM" of
"KENYA POWER
DISTRIBUTION SYSTEM
MODERNIZATION AND Hindi
220/33kV Substation". which one
shall us follow?
SCS is a term commonly used in KETRACO to describe
the Substation Automation and Control System.
Regardless the system employs computer or non-
computer topology, it is called as SCS. However to avoid
any further ambiguties, the employer wish to use the
following terminology for SCS:
a. RTU Topology (without BCU)
b. HMI Topology (with BCU)
The existing system in Hindi uses ABB RTU 560A which
has an integrated HMI (Human Machine Interface) for
supervision and control. The system is RTU based
topology, which is without a station level or bay computer
unit (BCU).
For the purpose of the tender the bidders shall follow the
existing drawings which indicates existing system at Hindi
is RTU Topology (without BCU).
76 For the optical fiber
communication system, we
noticed that the 400kV
transmission line between Nairobi
East substation and Lamu
substation is approximate 520km,
according to our experience, a
relay station must be arranged to
enhance the fiber communication
system. shall we take this relay
station into our bid price or there
is other contractor who will
conduct this work?
Please include in this bid
18 of 19
Employer : The Kenya Electricity Transmission Company Ltd 10.08.2015
Invitation to Bid No KETRACO/PT/010A,B&C/2015 – Lot A,B&C
Sr.
No.Ref Clause / Page Description Bidders Query KETRACO response
Design, Manufacture, test, Supply and Installation of 400 kV TRANSMISSION PROJECT
Clarification Lot C Technical List No.03
77 Hindi For Hindi 220kV substation,
Please provide the layout
drawings with proposed
extension scope, we cannot know
the location of the extension bay
so we cannot know the related
work of this extension.
Please refer to Addendum 03 (Lot C)
78 Volume 2 of 2 &
Pre-bid Replies
from KETRACO
Clarification
Lot C
Technical List
No.02, Item
No:4
Lot
C_Appendix
C.1_Schedule
of Technical
Particulars_N
East_Rev
1_25-05-15
As per the clarification, "For the
purpose of tendering the bidders
shall consider 10% impedance
and a tapping range of 400kV
+5/-15%/220kV."
However vendors confirmed that
this transformer with 10%
impedance is not possible and
even as per IEC 60076-5, page
no: 13, Table -1, Above 100 MVA
rating, minimum short circuit
impedance of the transformer
shall be >12.5%.
As per the Appendix-C Technical
Schedules ,
Hence, please suggest final %
impedance voltage (75degC),
rated frequency and full rating
required for the subject tender ,
- At principal tapping
- At maximum voltage ratio
- At minimum voltage ratio
IEC clearly states it is possible if the purchaser requires a
lower value. Therefore for the purpose of the tender
bidders shall use the specified values and ratings.
19 of 19