091 : 2000
CEB
STANDARD
MEDIUM VOLTAGE INSULATOR STRINGS
AND HARDWARE FOR COASTAL
APPLICATION (12KV & 36KV)
CEYLON ELECTRICITY BOARD
SRI LANKA
Specification
for
MEDIUM VOLTAGE INSULATOR STRINGS AND HARDWARE FOR COASTAL
APPLICATION (12KV & 36KV)
CEB Standard 091 : 2000
CEYLON ELECTRICITY BOARD
No. 50, Sir Chittampalam A. Gardener Mawatha, Colombo 2.
Sri Lanka
Telephone: 94-1-430471, 421720
Facsimile: 94-1-430473
E-mail : cebdp@mega.lk
CEB STANDARD 091 : 2000
CONTENTS
Page
1.
Scope
2
2.
System Psrsmeters
2
3.
Service Conditions
2
4.
Applicable Standards
2
5.
Technical Requirements
3
6.
Basic Features
4
7.
Quality Assurance
7
8.
Additional Requirements
7
9.
Information to be Supplied with the Offer
8
10.
Sample
9
11.
Inspection and Testing
9
12.
Annex.
10
1
CEB STANDARD 091 : 2000
SPECIFICATION FOR MEDIUM VOLTAGE
INSULATOR STRINGS AND HARDWARE FOR COASTAL APPLICATION
(12 kV and 36 kV)
1.0
SCOPE
This Specification covers the general requirements of design, manufacture, testing, supply and
delivery of Tension and Suspension Insulator Sets complete with Anti-Fog type Profile Disc
insulators with hardware fittings for 33kV and 11kV coastal overhead distribution systems.
2.0
SYSTEM PARAMETERS
a)
b)
c)
d)
e)
3.0
-
11kV
33kV
12kV
36kV
50Hz
50Hz
Effective
Non effective
13.1 kA 13.1 kA
-
30 deg. C
40 deg. C
90%
Humid tropical climate with
polluted atmosphere.
From M.S.L. to 1900 M
above M.S.L.
90 days.
SERVICE CONDITIONS
a)
b)
c)
d)
4.0
Nominal Voltage
System Highest Voltage
System Frequency
Type of earthing
System Fault Current (Sym.)
e)
Annual average ambient temperature
Maximum ambient temperature
Maximum Relative Humidity
Environmental condition
Condition
Operational Altitude
-
f)
Isokeraunic (Thunder day) level
-
APPLICABLE STANDARDS
The equipment and components supplied shall be in accordance with the latest editions of the
Standards specified below and amendments thereof. However the CEB Specification shall
supersede these Standards in the event there is a discrepancy.
a)
IEC 60120 (1984)
-
Dimensions of Ball and Socket Couplings
of String Insulator Units
b)
IEC 60305 (1995)
-
Characteristics of String Insulator Units of Cap & Pin
Type.
c)
IEC 60372 (1984)
-
Locking device for ball and socket couplings of string
insulator units: Dimensions and tests
d)
IEC 60383 (1993)
Part 1 & Part 2
-
Insulator for Overhead Line with Nominal
Voltage above 1000V.
2
CEB STANDARD 091 : 2000
5.0
e)
IECTR 61211 (1994)
-
Insulators of ceramic material and Steep wave front
impulse test on high voltage insulators.
f)
IEC 60575 (1977)
-
Thermal - mechanical performance test and
mechanical performance test on String Insulator
Units.
g)
IEC 60797 (1984)
-
Residual strength of string insulator unit of
glass or ceramic material for overhead lines
after mechanical damage of dielectric.
h)
IEC 60507 (1991)
-
Artificial pollution tests on high-voltage
insulators to be used on a.c. systems
i)
IEC/TR 60815 (1986)
-
Guide for the selection of insulators in respect of
polluted conditions
j)
ASTM C 151-84
ANSI C29-2 (1992)
-
Standard test method for Autoclave expansion
of Portland cement
k)
BSENISO 1461 (1999) -
Hot dip galvanised coating on iron and steel articles.
TECHNICAL REQUIREMENTS
a)
String Insulator unit ( Disc )
i)
ii)
iii)
iv)
v)
vi)
Type designation
Profile type
Porcelain diameter
Insulator spacing
Total Creepage distance
Protected creepage distance
-
U70 BLP / U120 BP
Anti - Fog type Profile
280mm
146mm
440mm
280mm
b)
Radio Interference
-
IEC60437-1997 (30dB)
c)
Data of Conductors to be used
-
Refer ANNEX B
d)
Insulator fixing cross-arm size
mm
-
100 x 50 x 6 channel
e)
Rated Voltage
kV
-
12
36
f)
Minimum Failing Load of the insulator string;
-
70
---
70
120
70
i)
ii)
iii)
Tension set for pole lines
Tension set for tower lines
Suspension set for tower lines
3
kN
kN
kN
CEB STANDARD 091 : 2000
g)
Insulation withstand Voltage
i)
ii)
h)
kV
kV
-
75
28
170
70
-
2
---
4
4
4
No. of Disc Insulator units in a string
i)
ii)
iii)
6.0
Dry Impulse(1.2/50 μs) peak
Wet power frequency (1 min.)
Tension set for pole lines
Tension set for tower lines
Suspension set for tower lines
BASIC FEATURE
6.1
Design
The insulators will be in service in a damp tropical saliferous climate having higher salinity level
where intense lightning storms at certain periods of the year are expected. The design shall
take this into account as well as to minimise the effect of local corona formation and discharge
likely to cause radio interference.
The design shall be such as to facilitate inspections, cleaning, repairs, and hot line
maintenance. All corresponding parts to be made to gauge and be interchangeable.
The conductor fittings shall be designed for a short circuit current of 10 KA for a duration of one
second. The Disc Insulator Set shall withstand such a short circuit current without damage to
component parts or welding between them.
6.2
Manufacture
6.2.1
String Insulator Units (Disc Insulators)
6.2.1.1 Insulators
The Insulators shall be made of good commercial grade wet process porcelain and shall be
`Type B' as per IEC 60383 (1993).
The insulator shall be of the Anti–Fog type profile design and cylindrically head type. The entire
surface of the porcelain insulator that will expose after (hardware) assembly shall be a smooth
uniform brown colour glazed surface.
The insulators shall have the correct shed formation to satisfy the specified flash- over
characteristics stipulated in the relevant standards and shall be of the type “U 70 BLP /
U120BP“ designation as per IEC60305'
6.2.1.2 Hardware
The hardware of the disc insulators shall be of the Cap and Pin Type with `16A' Ball and Socket
Couplings as per IEC 60120. The Caps of string insulator units shall be made of malleable cast
iron and the Pins shall be made of steel.
4
CEB STANDARD 091 : 2000
The steel pin shall be provided with a Zinc (sacrificial) anti-corrosion sleeve at the interface
between pin and internal cement, The thickness of the zinc sleeve shall not be less than 5mm
and it shall protrude not less than 10mm from the lower surface of the cement. To withstand the
damp tropical saliferous climate having higher salinity level, the cap shall be hot dip galvanized
and the thickness of galvanising coating shall not be less than 100 micron
The insulator head and cap shall be so designed to minimise the mechanical stresses
developed due to thermal expansion and to minimise electrical stress distribution.
6.2.1.3 Locking Device
The locking devices for the insulator units shall be made of Stainless Steel / Phosphor Bronze
Split Pin or Security (W) Clip and shall comply with IEC 60372 (1984).
The locking device shall prevent rotation of the disc insulators when the string is tensioned.
The design shall be such as to allow (hot line maintenance ) easy removal for replacing of
insulator units or fittings without the necessity to remove the insulator string from the cross
arms.
6.3
Tension (Insulator) Sets
6.3.1
For Pole Line application
The 12kV tension Insulator sets for pole line application shall have two (2) numbers of U70 BLP
disc insulator units as per Drawing No. CEB/DS&S/2000/91A
The 36kV tension Insulator sets for pole line application shall have four (4) numbers of U70 BLP
disc insulator units as per Drawing No. CEB/DS&S/2000/91A
6.3.2
For Tower line application
The 36kV tension Insulator sets for tower line application shall consists of four (4) numbers. of
U120 BP disc insulator units complete with necessary hardware fittings including compression
type conductor tension clamps, adjustable type arcing horns etc. as shown in the Drawing No.
CEB/DS&S/2000/91B.
6.4
Suspension (Insulator) Sets
The 36 kV Suspension Insulator sets for tower line application shall consist of four (4) numbers
of Disc Insulator Units complete with necessary hardware including conductor suspension
clamps, fixed type arcing horns etc. as per Drawing No. CEB/DS&S/2000/91C.
6.5
Insulator set fittings (Hardware) for Tension / Suspension sets
The Hardware fittings for tension and suspension set shall conform to BS 3288 (1997). and the
manufacturer shall furnish Type Test Certificate for all the hardware fitting used in the
tension/suspension sets.
5
CEB STANDARD 091 : 2000
6.5.1
Fitting for Tension Set
The tension insulator sets shall be complete with Ball Eye, Socket Eye, Anchor Shackle, Cotter
Pins, bolted / compression type Conductor Tension Clamps, Arcing Horns etc. as per Drawing
Nos. CEB/DS&S/2000/91A and CEB/DS&S/2000/91B.
The bolted type conductor tension clamp (Dead End Clamp) shall be made of aluminium alloy
with minimum three U bolts for attaching conductor as stipulated in Annex – B and as referred
to in the schedule of prices.
The compression type conductor tension clamp (Dead End Clamp) with jumper terminal shall
be made of aluminium alloy/steel and the jumper lug made of aluminium alloy shall be fixed to
the jumper terminal with two bolts. They shall be suitable to be used with the conductor as
stipulated in the schedule of prices and the conductor type, size and Across Flat Dimension of
the Die to be used is as per Annex B-1.
The Ball Eye (Horn holder), Socket Eye (Horn holder) and Anchor Shackle shall be made of
forged steel and their ultimate breaking load shall not be less that that of the insulator. Arcing
Horns (Adjustable type) and the Cotter Pins shall be made of Steel.
6.5.2
Fitting for Suspension Set
The suspension insulator sets shall be complete with Anchor Shackle/U Bolt, Ball Eye (Horn
Holder), Socket Eye (Horn Holder), Cotter Pin, Arcing Horn, Conductor Suspension Clamp etc.
as per Drawing Nos. CEB/DS&S/2000/91C. Conductor Suspension Clamp shall be made of
aluminium alloy with 2 U bolts for attaching conductors as stipulated in the Annex B-1 and as
referred to in the Schedule of Prices. The Anchor Shackle/U Bolt, Ball Eye and Socket Eye
shall be made of forged steel.
6.6
Prevention of Radio Interference
The design of all Insulator Hardware fittings and Accessories shall avoid sharp corners or
projections, which would produce high electrical stress in normal working. The design of
adjacent metal parts and mating surfaces shall be such as to prevent corrosion of the contact
surface and to maintain good electrical contact under service conditions.
6.7 Galvanizing
All insulator set hardware shall be galvanised after subjecting to the processes such as sawing,
shearing, drilling, punching, filing, bending and machining. Galvanizing shall be applied by hot
dip process to comply with the BSEN ISO 1461 (1999) specified.
The thickness of zinc coating shall not be less than 100 microns in plain surface. To prevent
the formation of white rust, all items shall be treated with sodium dichromate after galvanizing
and stored under well ventilated conditions.
6
CEB STANDARD 091 : 2000
6.8
Finish
The porcelain shall be sound, thoroughly vitrified and free from defects and blemishes which
might adversely affect the life of the insulator. The exposed parts of the porcelain shall be
smoothly glazed without any form of depression /defects.
Galvanized coating on all hardware components of the string insulator unit and insulator set
shall be smooth, continuous, uniform and free from flux stains and nodules of spelter.
7.0
QUALITY ASSURANCE
The manufacturer of insulators and hardware components shall posses ISO 9002 Quality
Assurance Certification for the manufacture of Porcelain Insulators and the hardware
components for the plants where the manufacture of Porcelain Insulators and the hardware
components is done. The Bidder shall furnish a copy of the ISO Certificate certified as true
copy of the original by the manufacturer, along with the offer.
8.0
ADDITIONAL REQUIREMENTS
8.1
Identification
The manufacturer's identification mark, minimum failing load ( kN ) and the year of
manufacture shall be permanently marked on the insulators as per IEC60383. All the
hardware fittings of the string insulator set shall also have the above marking except
the year of manufacture .
8.2
Routine Tests
The following routine tests as per BSEN/ IEC 60383 shall be carried out on all the items and the
routine test reports shall be made available for the observation of the CEB Inspector at the time
of inspection.
a)
b)
c)
8.3
Visual Inspection
Routine mechanical test
Routine electrical test
Packing
The string Insulators and Hardware Fittings & Accessories shall be packed separately in non
returnable palletised boxes suitable for overseas shipment to a tropical country.
The packing shall also be suitable to withstand rough handling without sustaining damages. In
packing cases where timber is used for reinforcement, the thickness of such timber parts shall
not be less than 25mm.
The Name of item, Voltage rating, Quantity and Weight shall be marked clearly on the outside
of all packages.
7
CEB STANDARD 091 : 2000
8.4
Manufacturing Experience
The manufacturer shall have at least 20 years of experience of manufacturing medium voltage
insulators (of same rating offered) to IEC/BS Standards. He shall furnish sufficient documentary
evidence in the Bid to prove his manufacturing experience
9.0
INFORMATION TO BE SUPPLIED WITH THE OFFER
9.1
The following shall be furnished with the Offer.
a)
b)
c)
d)
e)
f)
g)
h)
9.2
Catalogues describing all the item/components offered and indicating Model
Nos, Constructional features, materials used for components.
Complete dimensional drawings of all item.
ISO 9002-Quality Assurance Certification as per Clause 7.0 .
List of purchasers
Duly completed schedule of guaranteed technical particulars
Place of carrying out the Acceptance/Sample Tests as per Clause 11.2
Document to prove the manufacturing experience
The Bidder shall furnish a chart indicating their recommended Arc Horn Gap
settings for 11KV and 33Kv systems with Basic Insulation Levels as
stipulated in Clause 5.0 and the applicable altitudes from MSl up to1900m
above MSL for various pollution levels.
Type Test Certificate
i)
The following Type test Certificate as per BSEN/IEC60383 from a recognized
independent testing authority acceptable to CEB, shall be furnished with the
offer. The Test Certificates shall be given for string insulator unit (disc) as well
as for complete Suspension and Tension Insulator sets.
a)
b)
c)
d)
e)
ii)
Verification of the dimensions
Dry lightning impulse withstand voltage test
Wet- power frequency withstand voltage test
Electro-mechanical failing load test
Mechanical failing load test
The following Test Reports as per Standard specified for the string (disc)
insulator units shall also be furnished;
a)
b)
c)
d)
e)
Artificial pollution tests as per IEC60507 (1991) and IEC 815 (1986)
for disc insulator of Anti Fog profile type, the Salinity level to be 80
kg/m3
Thermal mechanical performance test as per IEC60575 -1977
Residual strength test as per IEC 60797:1984
Cement Auto Clave Expansion test as per ANSI C29-2:1992 &
ASTM C151.84
Power Arc test as per IEC 61467 1997
Offers of Bidders who failed to furnish the above particulars/certificates and the sample
as per Clause 10.0 shall be rejected.
8
CEB STANDARD 091 : 2000
10.0
SAMPLE
One complete sample of the each item / rating quoted (complete with specified hardware) shall
be supplied with the offer by the Bidder to facilitate analysis and evaluation of tender.
11.0
INSPECTION AND TESTING
11.1
Inspection
The selected Bidder shall make necessary arrangements for inspection by an Engineer of the
CEB and also to carryout in his presence Acceptance / Sample tests of the item offered. The
report of routine tests performed on the items shall be made available for the observation of the
Inspector
11.2
Acceptance/Sample Tests
The following acceptance/sample test as per BSEN 60383-1:1998 shall be witnessed by the
Engineer nominated by the CEB and cost of tests shall be born by the Bidder. The Bidder shall
clearly indicate the place of testing.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Verification of dimensionsVerification of displacements
Verification of the locking system
Temperature cycle test
Electro-mechanical failing load test
Mechanical failing load test
Puncture withstand test – As per IEC601211 (1994)
Porosity Test
Galvanizing Test
Steep Wave Front Test
The steep wave front test shall be performed on 10 disc insulators selected at random. Each
insulator shall be subjected to 10 (Ten) successive positive and negative impulse flash-over
with a wave having an effective rate of rise of 2500KV/μs. Then rated dry or wet power
frequency withstand voltage shall be applied to each disc insulator. If there is no electric
puncture, the insulators are considered to be successfully passed the test.
Failure of any one unit either in the steep front-of-wave test or subsequent power frequency
withstand voltage test shall cause for testing another 20 units. Failure of more than one unit
from the total so tested shall constitute failure to meet the requirements of this specification.
9
CEB STANDARD 091 : 2000
12.0
ANNEX
Drawings
A-1
CEB/DS&S/2000/91A
12kV &36 kV Tension Insulator string &
Hardware for pole line application
A-2
CEB/DS&S/2000/91B
36kV Tension Insulator string &
Hardware for tower line application
A-3
CEB/DS&S/2000/91C
36kV Suspension Insulator string &
Hardware for tower line application
B
Conductor and Die details for compression type tension clamps
C-1
Schedule of particulars - Properties of material used for insulator
C-2
Schedule of guaranteed technical particulars for Tension and suspension
insulator strings & Hardware.
10
CEB STANDARD 091 : 2000
11
CEB STANDARD 091 : 2000
12
CEB STANDARD 091 : 2000
13
CEB STANDARD 091 : 2000
ANNEX B
DIE DETAILS FOR COMPRESSION TYPE TENSION CLAMPS
(DEAD END CLAMPS)
CONDUCTOR
Code
Name
No. of
Strand/Wire
diameter
(mm)
O.D. of the
Conductor
(mm)
ACROSS FLAT DIMENSION
OF THE DIE TO BE USED
(mm)
DATA
Actual Area
of the
Conductor
(mm²)
Breaking
Load
Single
Part
Fittings
Two
Part
Fittings
(kN)
Lady Bird
(AAC)
7/2.79
8.38
43
7.4
17.3
Fly (AAC)
7/3.40
10.2
64
10.5
17.3
Wasp (AAC)
7/4.39
13.2
106
16.8
21.0
Weasel
(ACSR)
7/2.59
7.77
37
11.4
14.0
12.0
(Alu.)
5.4
(Steel)
Racoon
(ACSR)
7/4.09
12.3
92
27.4
21.0
17.3
(Alu.)
9.25
(Steel)
Lynx
(ACSR)
37/2.79
19.53
226
82.7
-
29.0
(Alu.)
13.5
(Steel)
AAAC
7/2.67
8.02
39
12.7
12.0
AAAC
7/4.25
12.74
100
30.8
17.3
AAAC
19/3.66
18.30
200
60.33
26.0
*
The Tension Clamp (Dead End Clamp) shall not permit slipping or cause damage to or
failure at a load less than 95% of ultimate strength of the Conductor.
14
CEB STANDARD 091 : 2000
ANNEX C - 1
SCHEDULE OF PARTICULARS
(This schedule shall be duly filled by the Manufacturer for each type of insulator offered)
Properties of Material used for Insulators
a)
Type
:
b)
Chemical Composition
:
c)
Porosity
d)
Bulk density
g/cm3
e)
Fatigue strength
N/mm2 :
f)
Tensile strength
N/mm2 :
g)
Impact strength
h)
Modules of elasticity
Gpa
i)
Mean Coefficient of linear
thermal expansion
10-6K-1 :
j)
Resistance to thermal shock
K
k)
Breakdown voltage
kV/mm :
l)
Dielectric constant
tan δ
:
m)
Resistivity
Ω
:
Volume %
:
:
N/mm2 :
:
:
I/We certify that the above data are true and correct.
-------------------------------------------------------------------------------------------------------------
SEAL AND SIGNATURE OF THE MANUFACTURER / DATE
15
CEB STANDARD 091 : 2000
ANNEX C - 2
SCHEDULE OF GUARANTEED TCHNICAL PARTICULARS
To be filled by the Manufacturer for each type and voltage rating offered )
TENSION
1.
2.
Name of manufacturer & country of origin
Insulator
i)
Type designation
ii)
Catalogue No
iii)
Profile type
iv)
Porcelain diameter
v)
Insulator spacing
vi)
Total Creepage distance
:
vii)
Protected Cteepage distance
:
:
:
:
:
3.
Type of insulator material
:
4.
Complete insulator set
i) Rated Voltage
ii) Rated Frequency
iii) Rated withstand Voltages
:
kV
Hz
:
:
kV
kV
:
:
kV
kV
:
:
kV
kV
:
:
kN
:
a) Lightning Impulse
1)
2)
Positive Peak
Negative Peak
b) 1 Minute Power Frequency
1)
2)
Wet
Dry
c) Power frequency flashover voltages
i)
ii)
Wet
Dry
d) Minimum failing load
e) Number of disc insulator
Units in the set
Nos
f) Distance between centres
of disc insulator units
5.
mm
:
kV
mm.
mm.
kN
:
mm.
:
%
%
:
:
:
:
For insulator Disc unit
a)
b)
c)
d)
e)
f)
g)
h)
i)
6.
:
Power frequency
Puncture Voltage
Total Creepage Distance
Protected Creeping distance
Minimum Failing load
Size of ball and socket coupling
Out side diameter of disc
Thickness of zinc sleeve mm
Purity of zinc sleeve
Zinc sleeve fused area
Applicable Size of conductors
(indicate the range of sizes of
conductors)
:
:
:
:
16
SUSPENSION
CEB STANDARD 091 : 2000
7.
Radio Interference noise level at
Standard test voltage
8.
Dry Arcing Distance of the
Complete Units
9.
Material and Type of
i)
ii)
:
mm
Tension Clamp
Suspension Clamp
:
:
10.
Overall Length of the complete Unit
11.
Whether the following type test certificates
as per IEC 60383 are furnished
a)
b)
c)
d)
12.
14.
15.
16.
mm
Verification of the dimensions
Wet- power frequency
withstand voltage test
Electro-mechanical
failing load test
Mechanical failing load test
:
Yes/No :
Yes/No :
Yes/No :
Yes/N :
Whether the following Type Test Certificates
As per Standard specified for the disc
Insulator units are furnished;
a)
Thermal mechanical performance
test as per IEC60575
Yes/No ;
b)
Residual strength test
as per IEC 60797;1984
Yes/no :
Cement Auto Clave Expansion
test as per ANSI C29-2
Yes/No :
c)
13.
:
Artificial pollution test
IEC 60507
Salinity level
as per
Yes/No :
g/m3
Whether the type test certificates as
per BS 3288 for insulator set fitting
(Hardware) furnished)
:
Yes/No :
Whether the ISO 9002 Quality
assurance certificates for the
following are furnished
a)
Insulator
Yes/No ;
b)
Insulator set Fitting
Yes/No ;
Whether the chart indicating the Arc
Horn Gap settings as per
Clause 9.1 h) furnished.
Yes/.No :
17
CEB STANDARD 091 : 2000
17.
Whether the following acceptance test
as per Clause 10 will be carried out
during the inspection and whether the place
of testing is indicated
a)
b)
c)
d)
e)
f)
g)
h)
i)
Verification of dimensions
Yes/No
Place of testing
Verification of displacements
Yes/No
Place of testing
Verification of the locking system
(Ball & Socket Couplings)
Yes/No
Place of testing
Temperature cycle test
Yes/No
Place of testing
Mechanical performance test
followed by Electro-mechanical
failing load test
Yes/No ;
Place of testing
Puncture withstand test Yes/No :
Place of testing
Porosity test
Yes/No
Place of testing
Galvanizing Test
Yes/No
Place of testing
Steep wave front tests
Yes/No
Place of testing
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
:
I/We certify that the above data are true and correct
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SEAL AND SIGNATURE OF THE MANUFACTURER / DATE
18