DL/T 1000.3-2015 English PDF (DLT1000.3-2015)

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DL/T 1000.3-2015: Application guide of insulators for overhand lines with a nominal voltage over 1000V Part 3: Composite insulator for a.c. system
DL/T 1000.3-2015
DL
ELECTRICAL INDUSTRY STANDARD
OF THE PEOPLE?€?S REPUBLIC OF CHINA
ICS 29.020
K 48
Filing No.: 50770-2015
Replacing DL/T 864-2004
Application guide of insulators for overhead lines with a
nominal voltage over 1000V - Part 3: Composite insulator
for a.c. system
ISSUED ON: JULY 01, 2015
IMPLEMENTED ON: DECEMBER 01, 2015
Issued by: National Energy Administration
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 General technical requirements ... 8
5 Selection principles ... 10
6 Inspection ... 12
7 Storage and transportation ... 14
8 Acceptance and installation ... 15
9 Daily inspection and maintenance ... 16
10 Technical management ... 18
Appendix A (Normative) Method for measuring the minimum thickness of shed and
sheath ... 20
Appendix B (Informative) Recommendations for uniformity voltage fittings for 110 kV
~ 1000 kV composite insulators ... 22
Appendix C (Normative) Sampling acceptance test of composite insulators ... 24
Appendix D (Informative) Statistics of composite insulator damage (Failure) ... 26
Application guide of insulators for overhead lines with a
nominal voltage over 1000V - Part 3: Composite insulator
for a.c. system
1 Scope
This Part specifies the general technical requirements, selection principles, inspection,
storage and transportation, acceptance and installation, daily inspection and
maintenance, technical management of rod-shaped suspension composite insulators for
AC overhead lines, which have a nominal voltage higher than 1000 V.
This Part applies to composite insulators (referred to as composite insulators) for AC
overhead power lines, which have a nominal voltage higher than 1000 V and a
frequency of 50 Hz, as well as power plants and substations. The installation site is
below 1000 m above sea level; the ambient temperature is between -40 ??C ~ +40 ??C.
This Part includes requirements for selecting composite insulators according to specific
operating conditions.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB 311.1 Insulation co-ordination - Part 1: Definitions, principles and rules
GB/T 311.2 Insulation co-ordination - Part 2: Application guide
GB/T 4585 Artificial pollution tests on high-voltage insulators to be used on a.c.
systems
GB/T 19519 Insulators for overhead lines - Composite suspension and tension
insulators for a.c. systems with a nominal voltage greater than 1000 V - Definitions,
test methods and acceptance criteria
GB/T 21421.1 Composite string insulator units for overhead lines with a nominal
voltage greater than 1000 V - Part 1: Standard strength classes and end fittings
GB/T 21421.2 Composite string insulator units for overhead lines with a nominal
voltage greater than 1000 V - Part 2: Dimensional and characteristics
GB/T 26218.1 Selection and dimensioning of high-voltage insulators intended for
use in polluted conditions - Part 1: Definitions, information and general principles
GB/T 26218.2 Selection and dimensioning of high-voltage insulators intended for
use in polluted conditions - Part 2: Ceramic and glass insulators for a.c. systems
GB 50545 Code for design of 110 kV ~ 750 kV overhead transmission line
DL/T 368 The correction of high altitude on pollution external insulation for
insulators used in transmission line
DL/T 376 General technical requirements of silicone rubber insulation materials for
composite insulators
DL/T 741 Operating code for overhead transmission line
DL/T 859 Artificial pollution tests on composite insulators used on high-voltage AC
systems
DL/T 1122 Technical guide of insulation coordination selection for overhead
transmission line
DL/T 1474 Hybridity measuring method of composite insulator for AC and DC
overhead lines with a normal voltage greater than 1000 V
JB/T 11219.1 End fitting for composite insulator with a high voltage overhead line.
Part 1: End fitting for string insulator units
3 Terms and definitions
The following terms and definitions as defined in GB/T 19519 are applicable to this
document.
3.1
Uniformity voltage fitting
A device installed on the metal accessories, which can firstly improve the potential
distribution of the composite insulator, protect the metal accessories, core rods and
sheds from arc burns, secondly protect the connection areas of the metal accessories
at both ends from damage to the sealing performance due to leakage tracking and
erosion. The uniformity voltage fitting can be a uniformity ring, a uniformity arc
starter ring or a semiconductor polymer device.
3.2
level of the composite insulator after installing the designed uniformity volage fitting
shall not exceed 500 ??V, at the specified 1.1 times the maximum operating phase
voltage ( , where Um is the maximum operating voltage).
4.6.3 Artificial pollution power frequency withstanding performance
Composite insulators shall meet the requirements of artificial pollution power
frequency withstanding voltage test. A test voltage of is applied to the
composite insulator, to withstand the given test salt density (SDD) and ash density
(NSDD). The test procedure and criteria are carried out in accordance with GB/T 4585
and DL/T 859.
4.6.4 Power frequency arc performance
Composite insulators shall meet the requirements of power frequency arc test. The
design of the end accessories of composite insulators shall take into account the
influence of arc. The short-circuit current and duration may cause damage to the end
accessories, core rods, sheds; appropriate arc protection devices shall be designed.
4.7 Mechanical properties
4.7.1 Rated mechanical tensile load level
The rated mechanical tensile load of composite insulators should be selected from the
following levels: 70, 100 (120), 160, 210, 300, 400 (420) kN, 530 (550) kN. The
strength grades outside the brackets shall be preferred.
4.7.2 Test load
For newly put into operation composite insulators which have voltage levels of 330 kV
and above, the average value of the mechanical destructive load minus 3 times the
standard deviation shall not be less than the rated mechanical tensile load (SML).
Note: For special projects, for example, composite insulators with strength grades of 300 kN
and above used in 750 kV and above UHV projects should also withstand for 24h without
damage under 1.2 SML.
If the composite insulator is subjected to obvious compression, torsion, bending and
other forces during use, the test method and test load shall be determined by negotiation
between the supplier and the buyer.
5 Selection principles
5.1 General principles
In the newly-built, expanded, rebuilt power transmission and transformation projects,
the selection of composite insulators shall follow the principle of "mature technology,
advanced process, reliable quality and operating experience". Before new products are
used in batches, they must pass the type-finalization test; the trial operation time shall
not be less than 1 year.
The annual damage rate of operating composite insulators shall be less than 0.05%.
5.2 Unified specific creepage distance (USCD) and creepage factor
Under general regional environmental conditions, the unified specific creepage distance
(USCD) and creepage factor of composite insulators shall meet the requirements of
GB/T 26218.1, GB/T 26218.2, DL/T 1122.
For composite insulators used in special areas (such as high dust pollution areas, heavy
pollution areas, heavy ice areas, etc.), if they are restricted by conditions such as
structural height, the creepage factor (CF) can be determined by negotiation between
the supplier and the buyer.
5.3 Uniformity voltage fitting
a) The uniformity voltage fitting shall be designed to control the field strength at the
end of the composite insulator within 4 kV/cm. It can be appropriately relaxed in
special circumstances, but the maximum shall not exceed 5 kV/cm.
Note: The field strength at the end of 1000 kV UHV composite insulators should be
controlled within 5 kV/cm.
b) For composite insulators with double-section structure, the middle connection
part shall be equipped with a uniformity voltage shielding device that meets the
relevant technical requirements of field strength control and anti-corona.
c) The material of the uniformity voltage fitting should be aluminum alloy; it shall
have sufficient mechanical strength. The pipe diameter, ring diameter, shielding
depth of the uniformity voltage ring shall meet the relevant technical
requirements of field strength control and anti-corona.
d) The uniformity voltage fittings at the high-voltage end and the grounding end
shall meet the requirements of the power frequency arc for composite insulators.
e) When designing the uniformity voltage fitting, the installation position of the
uniformity voltage fitting shall be unique.
f) Whether to use the bird-proof uniformity voltage fitting is determined by the
purchaser.
g) Composite insulators with voltage levels of 110 kV and above shall be equipped
checked for obvious signs of extrusion or damage. Store after the outer packaging is
qualified.
7.1.2 Warehouse storage
Composite insulators shall be stored in a dry and ventilated warehouse, to prevent
damage caused by external forces such as water immersion and rat bites. It is prohibited
to directly press heavy objects on the composite insulators or stack objects with sharp
edges, to avoid deformation of the shed or mechanical damage. The stacking height of
the packaging shall meet the requirements of the manufacturer and should not exceed
8 layers.
7.1.3 Outdoor storage
In addition to meeting the above requirements, outdoor storage shall also take rain
protection measures.
7.2 Transportation
7.2.1 General requirements
The transportation specified in this Part refers to the transportation of composite
insulators from the storage location to the installation site. Transportation and handling
must be carried out when the packaging is intact.
7.2.2 Automobile transportation
When using automobile transportation, the stacking of composite insulator packaging
boxes (tubes) shall meet the above provisions of this Part. It is strictly forbidden to drag
or throw during unloading, to ensure that the packaging boxes (tubes) land smoothly.
7.2.3 Manual handling
When carrying a long (more than 4 m) packaging box (tube) containing composite
insulators, it shall be carried by 3 or more people manually according to the position
marked on the outer packaging. For long composite insulators, measures shall be taken
to avoid damage to the composite insulators.
8 Acceptance and installation
8.1 Acceptance
8.1.1 Acceptance content
The acceptance content before installation of composite insulators generally includes:
a) Factory certificate;
b) Consistency between packing list and accessories;
c) Installation instructions;
d) Locking pin;
e) Contents specified in the contract.
8.1.2 Appearance inspection
Check whether the outer packaging is intact; check the specifications and models;
remove the outer packaging on site to check the appearance of the composite insulator.
The appearance of the composite insulator shall comply with the requirements of GB/T
19519. If it is found that it does not meet the requirements or the shed has permanent
deformation that reduces the shed spacing by more than 1/3, it should not be used.
Composite insulators with torn sheds, damaged sheaths or damaged end seals shall not
be used.
8.1.3 Acceptance test
The acceptance test shall meet the requirements of Appendix C of this Part.
8.2 Installation precautions
a) Handle with care; do not throw; avoid collision and friction with sharp objects.
b) When lifting, the rope knot shall be tied on the metal accessories; it is forbidden
to tie it directly on the shed.
c) It is forbidden to step on the shed of composite insulators.
d) Correctly install the uniformity voltage fitting; pay attention to install it in place;
do not install it upside down; carefully adjust the ring surface to be perpendicular
to the axis of the composite insulator. For open-type uniformity voltage fittings,
pay attention to the same opening direction at both ends.
e) For composite insulators used in areas where bird pecking occurs frequently, bird
pecking protection measures shall be taken before live operation.
9 Daily inspection and maintenance
9.1 Daily inspection
For composite insulators that have been in operation, daily inspections, pole climbing
inspections, regular monitoring shall be carried out in accordance with the provisions
of DL/T 741. The inspection contents shall include:
e) When the pole or tower is applied with anti-rust paint, the composite insulator
shall be covered, to prevent the paint from dripping onto the surface of the
composite insulator;
f) Special maintenance measures shall be taken for special dirty areas;
g) When the hydrophobicity of the composite insulator surface has not disappeared
permanently and no obvious discharge occurs in rainy and foggy weather, it can
continue to be used.
9.3.1.2 If any of the following conditions occur in the composite insulator, it shall be
replaced:
a) The shed becomes embrittled (the shed cracks when folded);
b) The hydrophobicity drops to HC6 or disappears permanently;
c) The sheath is damaged and endangers the core rod;
d) The shed is damaged in large quantities (more than 1/4 of the shed);
e) The shed and sheath are severely burned;
f) The sealing of the connection parts of the composite insulator fails, cracks, slips;
g) The composite insulator does not meet the safety operation requirements after the
testing items are tested;
h) The infrared tem...