Annex (B) Technical Specifications for 11kV & LV Distribution Overhead Line Supports 1. SCOPE This Technical Specification has been prepared by MOE. This specification covers the provision of tubular steel supports, crossarms, fittings and accessories suitable for 11kV overhead lines with maximum conductor size 120/20 ACSR and LV lines with maximum conductor size 120mm 2 AAC. It supersedes all previous specifications for 11kV & LV distribution overhead line supports that have been issued by MOE. 2. GENERAL REQUIREMENT The equipment shall generally, except where varied by this specification, comply with the appropriate requirements of all relevant sections of ISO/CEN, current at the time of bidding. When bidding, all non-compliances with the appropriate Standards shall be stated by the Manufacturer. Service Conditions Altitude: Up to 1000metres above sea level Ambient temperatures: Outdoor: Maximum peak: +55⁰C Maximum daily average: +40⁰C Maximum yearly average: +30⁰C Lowest minimum: -10⁰C Highest one day variation: +25⁰C Ground maximum: +35⁰C Indoor: Maximum Daily Average: +35⁰C Humidity: Max relative humidity: 92% Min relative humidity: 12% Yearly average: 44% Wind: Max wind velocity: 140km/hr (for design purposes) Rain fall:
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Annex (B)
Technical Specifications for 11kV & LV
Distribution Overhead Line Supports
1. SCOPE
This Technical Specification has been prepared by MOE. This specification covers
the provision of tubular steel supports, crossarms, fittings and accessories suitable for
11kV overhead lines with maximum conductor size 120/20 ACSR and LV lines with
maximum conductor size 120mm2 AAC. It supersedes all previous specifications for
11kV & LV distribution overhead line supports that have been issued by MOE.
2. GENERAL REQUIREMENT
The equipment shall generally, except where varied by this specification, comply with
the appropriate requirements of all relevant sections of ISO/CEN, current at the time
of bidding. When bidding, all non-compliances with the appropriate Standards shall
be stated by the Manufacturer.
Service Conditions
Altitude: Up to 1000metres above sea level
Ambient temperatures:
Outdoor:
Maximum peak: +55⁰C
Maximum daily average: +40⁰C
Maximum yearly average: +30⁰C
Lowest minimum: -10⁰C
Highest one day variation: +25⁰C
Ground maximum: +35⁰C
Indoor:
Maximum Daily Average: +35⁰C
Humidity:
Max relative humidity: 92%
Min relative humidity: 12%
Yearly average: 44%
Wind:
Max wind velocity: 140km/hr (for design purposes)
Rain fall:
Minimum yearly: 50mm
Maximum yearly: 500mm
Maximum in one day: 65mm
Yearly average: 150mm
Atmosphere:
General: Subject to sand storms and
windblown dust.
Average number of days of dust
storms: 21.5
Average number of day of thunder
storms: 15
Soil Conditions:
Ground Thermal Resistivity: C m/watt or as determined by 01.20
local test
NETWORK PARAMETERS
Parameter Network
11 kV LV
Nominal Voltage 11kV 0.416kV
Highest System Voltage 12kV 0.454kV
Number of Phases 3 3
Frequency 50Hz 50Hz
Neutral Point Resistance or
reactance earthed
Solidly Earthed
3 Phase Short Circuit Capability 31.5 kA 12kA
Duration of Short Circuit 1 sec 1 sec
Impulse Withstand Voltage (wet) 75kV 3kVp
Power Freq. Withstand Voltage 1
min (wet)
28kV 2kV
Minimum creepage distance
(mm/kV)
25 25
3. SCHEDULED EQUIPMENT
Load Cases
Case 1: Working load + self weight + wind on structure (Ps)
Case 2: (Working load + self weight + wind on structure) x 1.5 (Pp)
Case 3: (Working load + self weight + wind on structure) x 2.5 – Destruction
(Pb)
Tubular steel poles shall be supplied to the following dimensions and classifications.
Type 1 Type 2
Effective length (M) 11.00 9.00
Top Section
Length x outside
diameter (mm) 3100 x 216.3 2000 x 165.2
Minimum wall
thickness (mm) 3.5 3.5
Middle Section
Length x outside
diameter (mm) 3050 x 267.4 2300 x 216.3
Minimum wall
thickness (mm) 4.5 4.5
Bottom Section
Length x outside
diameter (mm) 4850 x 318.5 4700 x 267.4
Length x outside
diameter (mm) 4850 x 318.5 4700 x 267.4
Minimum wall
thickness (mm) 5.0 5.0
Sinking Depth (M) 1.8 1.5
Working Load
(kgf) 700 700
Point of load
application from
top (M)
1.2 0.6
Factor of Safety
Case 1(Ps) 1.0 1.0
Factor of Safety
Case 2(Pp) 1.5 1.5
Factor of Safety
Case 3(Pb) 2.5 2.5
Maximum
deflection Case 1
(mm)
0.0 0.0
Maximum
deflection Case 2
(mm) 13.0 13.0
Min yield strength
≥ N/mm² 340
Tubular Steel Supports
Supports shall be manufactured from longitudinally welded tube sections of hot rolled
is responsible Contractor). The 2carbon steel of minimum yield strength ≥340 N/mm
for ensuring that the final design complies with the load cases stated in section of 3.1
of this specification.
Steel shall have a low silicon and phosphorus content (Si <0.04%. P<0.02%).
The poles shall be manufactured using the following methods:-
Type 1 and type 2 – Welded sections
The Contractor shall submit, with the bid, drawings showing overlap lengths in the
case of welded sections and detail dimensions of all filling pieces used in the
manufacture of welded section poles.
All supports shall be galvanized using the hot dip method according to ISO 1461.
Drillings
Poles shall be drilled according to the dimensions given in Figs 1 & 2. All
holes shall be drilled prior to the galvanizing process and have smooth
uniform finish after galvanizing.
Pole Cap
Each pole shall be supplied with a pole cap, to seal the aperture at the top of
the pole. The cap shall be manufactured according to the dimensions given in
Figs 1 – 2. ‘A’ Clamps
Type 1 poles shall have welded to the top, an ‘A’ clamp for the purpose of
supporting the pin stalk of a top phase insulator. The additional height due to
the attachment of the clamp shall not be considered as part of the effective
length of the pole and, where measurements are quoted “from the pole top”,
they refer to the top of the main pole structure.
The A shaped clamps shall be manufactured according to the dimensions in
Figs 1 from steel plate of the same grade and properties as the material of the
main pole and the completed clamp shall be welded to the pole before
galvanizing. All welding and drilling involved in the manufacture of the ‘A’
Clamp will be carried out prior to the galvanizing process.
Crossarm (Strain)
Each Type 1 pole shall be supplied with a cross arm and its associated clamp according
to the dimensions in Fig 1. The cross-arm is intended to be fixed to the pole by means of
the clamp at a distance of 600mm below the pole top. Every set shall include the
following:
One galvanised steel channel cross arm according to the dimensions given in Fig
1 manufactured from steel of grade S235JR:
One galvanised steel clamp according to the dimensions given in Fig 1
manufactured from steel of grade S235JR:
Two galvanised, high-tensile steel M16 x 60 bolts with a minimum threaded
length of 50mm. Each bolt shall be supplied complete with a galvanised nut,
plain washer and spring washer.
Galvanising
Galvanizing shall be in accordance with ISO 1459 and ISO 1461. The zinc coating shall
and minimum thickness in any one place shall be 85 microns. 2not be less than 650g/m
Poles and other hollow items shall be galvanized both inside and out.
The zinc coating shall be smooth, continuous and uniform. It shall be free from acid
spots and shall not scale, blister or be removable by handling or packing. There shall be
no impurities in the zinc or additives to the smelter bath that could have a detrimental
effect on the durability of the zinc coating
Before pickling, all welding, drilling, cutting and grinding shall be completed and all
grease, paint, varnish, oil and welding slag shall be completely removed. All
protuberances which could affect the life of galvanizing shall also be removed.
To avoid the formation of white rust all galvanized material shall be packaged in such a
way to ensure adequate ventilation between parts during shipping and storage.
5. QUALITY CONTROL
The Contractor shall submit evidence of ISO 9001 accreditation with his bid. The
Contractor shall also submit detailed quality control procedures with his bid. Any
potential Contractor that does not submit these documents shall be disqualified from
the evaluation process.
Random samples from each batch shall be inspected by the Employer’s engineers or
the Employer’s nominated inspector. The minimum quantities for sampling from each
batch are listed in the table below:
Batch size Number of poles
up to 500 5
501 - 1000 8
1001 - 2000 13
2001 - 3000 18
3001 and above 20
The Contractor shall aid the work of the Employer’s inspector by providing copies of
all relevant standards, and allowing the inspector full use of the necessary tools,
instruments and laboratory equipment, together with ample space and assistance in the
handling of poles for inspection. Any costs incurred in assisting with the inspections
shall be borne by the Contractor.
The following parameters shall be examined:
General appearance
Finish
Dimensions
Sweep
Thickness and appearance of galvanising
As a minimum requirement, the following dimensional checks shall be witnessed by
the inspector:
Dimension Tolerance
Length +0.25%
Butt diameter and circumference +2.5%
Top diameter and circumference +2.5%
Wall thickness +10%
Concentricity ±1%
Accuracy of drillings ±0.5%
Sweep, where appropriate ±1%
Crossarms, clamps and fittings shall have the following parameters examined:
General appearance
Finish
Dimensions
Straightness
Appropriate markings
Accuracy of drillings
Thickness and appearance of galvanising
As a minimum requirement the following dimensional checks shall be witnessed by
the inspector:
Dimension Tolerance
Length +0.25%
Cross section of cross arm +10%
Dimensions of clamp +2.5%
Position and size of suspension holes ±0.5%
Verticality of all through holes ±0.5%
The group of poles or fittings offered at any one time shall constitute a batch. Within
a batch, poles and fittings presented for inspection shall be segregated on a size basis.
If the inspected items have damage or deviations on a quantity greater than 5% of the
batch, then the entire batch shall be unconditionally rejected without further sorting.
Poles delivered to stores or sites shall be free of all damage to protective zinc coating,
and shall not be out of straight by more than one thousandth of the length of the pole.
. DRAWINGS
Fig 1: Type 1 Tubular Steel Pole c/w Accessories
Fig 2: Type 2 Tubular Steel Pole
TECHNICAL SCHEDULES
To be completed by all Contractors:
Schedule A: Type 1 Tubular Steel Pole
Item
Number Description Unit Offer
1 Weight kg
2 Wall thickness
a Bottom section mm
b Middle section mm
c Top section mm
3 Length of sections
a Bottom section mm
b Middle section mm
c Top section mm
4 Outside diameter of sections
a Bottom section mm
b Middle section mm
c Top section mm
5 Effective length of pole M
6 Manufacturing method
(swaged/welded)
7 )sWorking load (P kg
8 pDeflection at P mm
9 )bBreaking load (P kg
10 Factor of Safety (FOS)
11 Type of corrosion prevention system
used
(Details and specification utilised to be
enclosed)
12 Grade and specification of steel
Schedule B: Type 2 Tubular Steel Pole
Item
Number Description Unit Offer
1 Weight kg
2 Wall thickness
a Bottom section mm
b Middle section mm
c Top section mm
3 Length of sections
a Bottom section mm
b Middle section mm
c Top section mm
4 Outside diameter of sections
a Bottom section mm
b Middle section mm
c Top section mm
5 Effective length of pole M
6 Manufacturing method
(swaged/welded)
7 )sWorking load (P kg
8 pDeflection at P mm
9 )bBreaking load (P kg
10 Factor of Safety (FOS)
11 Type of corrosion prevention system
used
(Details and specification utilised to be
enclosed)
12 Grade and specification of steel
Annex (C)
Technical Specifications for
Overhead Line Conductors
1. SCOPE
This specification covers the design, manufacture, testing, supply, delivery, and
performance requirements of bare overhead conductors, and earthing conductors
for use in the networks of the MoE.
2. STANDARDS
The equipment shall comply with the latest editions of, and amendments to, the
international standards listed in Part 2. Where any provision of this specification
differs from those of the standards listed hereafter, the provision of this
specification shall apply.
In case of conflict, the order of precedence shall be:
This specification
IEC Standards
ISO Standards
Other Standards
3. SERVICE CONDITIONS
The service conditions shall be as follows:
Altitude
Maximum outdoor ambient shade temperature
Minimum outdoor ambient shade temperature
: Up to 1000m above sea-level
: 50°C
: -10°C
Maximum daily mean temperature
Maximum relative humidity
Maximum wind (gust) speed
Isokeraunic level
Pollution level
Maximum Rainfall
Maximum ground temperature
: 40°C
: 92%
: 140 kilometre per hour
: 15
: Frequent and strong dust storms
: 500mm.
: 35°C at 100mm depth.
2. INSPECTION, TESTING
2.1 Inspection
The Contractor shall submit a detailed programme covering the design,
manufacture testing and delivery of the equipment within one month of receipt
of the contract award.
Reports shall subsequently be submitted at monthly intervals outlining
progress and, if necessary, explaining deviations from the program.
The Employer shall have free entry at all times, while work on the contract is
being performed, to all parts of the manufacturer's works which concern the
processing of the equipment ordered. The Contractor shall afford the
Employer, without charge, all reasonable facilities to satisfy him or herself
that the equipment being furnished is in accordance with this specification.
2.2 Testing
Samples of conductors shall successfully pass all the tests referred to in Part 2
of this specification and those listed in the most recent edition of the standards
listed in Part 2 of this specification.
Each separate consignment of conductor shall be accepted or rejected by the
Employer on the basis of the results of the before or after stranding tests
carried out on individual items sampled out of the consignments ready for
dispatch, as described in Part 2 of this specification. The Employer reserves
the right to reject an item of equipment if the test results do not comply with
the values specified or with the data given in the technical data schedule.
The Employer shall have the tests witnessed by a representative. In order to
facilitate this, the Contractor shall give the Employer a minimum of four
weeks notice that the material is ready for testing. If the Employer does not
indicate his or her intention to participate in the testing, the manufacturer shall
carry out the tests and the Contractor shall submit the test reports to the
Employer.
The Contractor shall submit full details of the proposed methods of testing for
approval to the Employer, at least one month before testing.
All costs in connection with the testing shall be borne by the Contractor who
shall provide the Employer with all the test facilities, which the latter may
require, free of charge. The Employer shall have the right to select the samples
and shall also have the right to verify that the testing apparatus is correct.
The Contractor shall submit to the Employer five signed copies of the test
certificates, giving the results of the tests as required. No materials shall be
dispatched the Employer has received the test certificates and the Contractor
has been informed that they are acceptable.
The test certificates must show the actual values obtained from the tests, in the
units used in this specification, and not merely confirm that the requirements
have been met.
The Employer may decide to have the material inspected after receipt and the
Employer shall have the right to select the samples if desired.
3. QUALITY ASSURANCE
The manufacturer must operate a quality assurance system that complies with
ISO 9000. The Contractor shall provide current certification showing the
manufacturers’ compliance with ISO 9000 or equivalent national standard. The
certificate must have been issued by an independent, accredited issuing
authority.
4. PRODUCTION AND DELIVERY PROGRAMME
The Contractor shall submit a detailed programme covering the manufacture,
testing and delivery of the materials and equipment within the time stated in
Part 2 of this specification. The programme shall be in the form of a bar chart.
The Contractor shall submit progress reports detailing progress against this
programme and explaining any variations. The progress reports shall be
submitted at the frequency stated in Part 2 of this specification.
5. PACKING AND SHIPPING
5.1 Packing
All conductors shall be wound on non-returnable strong wooden drums
suitably treated for outdoor storage and capable of withstanding all normal
transportation and handling. Drum diameter and width shall be limited to 2280
mm and 1140 mm respectively. All nails and metallic parts on the inner
surfaces must be countersunk so that they cannot damage the conductor. Old
nails remaining from previous use of the drum shall be removed. Drums shall
not be treated with chemicals injurious to the conductors. A round spindle hole
of minimum diameter 70mm is required at the centre of all wooden drums.
Each end of conductor shall be durably sealed before shipment to prevent
ingress of moisture. The drums shall be lagged or covered with suitable
material to provide physical protection for the conductors during transit and
during storage and handling operations. The lagging shall provide suitable
protection against all climatic conditions prevailing during transport and on
site.
The packing shall provide suitable protection against all climatic conditions
prevailing during transport and on site.
Material liable to deterioration by sea water, moisture, or ingress of foreign
matter shall be suitably protected.
Each drum or case shall carry the following information, clearly and indelibly
marked on a metal or plastic plate, affixed to it in a non detachable manner:
individual drum serial number;
Employer's name;
contract number;
Contractor's name;
manufacturer's name;
description of contents;
conductor size and stranding;
length of conductor in the drum, in metres;
direction of roll;
country of origin;
case or drum measurements;
gross and net weights in kilograms; and
all necessary slinging and stacking instructions.
Each case or drum shall contain a fully detailed packing list in a sealed
waterproof envelope.
Five copies of each packing list shall be sent to the Employer prior to dispatching
the equipment.
PART 2: TECHNICAL
6. APPLICABLE STANDARDS
The equipment shall comply with the latest editions of, and amendments to, the
international standards listed below. Where any provision of this specification
differs from those of the standards listed below, the provisions of this
specification shall apply:
ISO International Organization for Standardization
HD 532: Hard drawn Aluminium wire for overhead line
conductors
ISO 752: Zinc ingots
ISO 2107: Aluminium, Magnesium, and their alloys - Temper
designations
ISO 6892: Metallic Materials - Tensile Testing
ISO 7800: Metallic materials - wire - simple torsion test
ISO 7801: Metallic materials - wire - reverse bend test
ISO 7802 : Metallic materials - wire - wrapping test
ISO 9000: Quality management and quality assurance standards
ISO 9591: Corrosion of Aluminium Alloys
ISO 9649: Metallic materials - wire - reverse torsion test
International Electrotechnical Commission
IEC 60104: Aluminium - magnesium - silicon wire for
overhead line conductors
IEC 60468: Method of measurement of resistivity of
metallic materials
IEC 61394: Overhead lines – Characteristics of
greases for aluminium, aluminium alloy and steel bare
conductors
IEC 60395: Overhead electrical conductors – Creep
test procedures for stranded conductors
IEC 60888: Zinc coated steel wires for stranded conductors
IEC 60889: Hard Drawn Aluminium wire for overhead line