Technical specification for black crosslinkable polyethylene insulating material for overhead insulated cable

Author：hlyb Add Time：2016-04-19 11:22:37

1 Scope

This specification specifies the technical requirements, test methods, inspection rules, packaging, marking, transportation and storage of black crosslinkable polyethylene insulating material for overhead insulated cables of 10kV and below. It is suitable for peroxide crosslinked polyethylene, silane crosslinked polyethylene and irradiation crosslinked polyethylene insulating materials based on low density polyethylene or mixed with polyethylene copolymer.

2 reference standards

GB / T 1040-1992 test method for tensile properties of plastics

GB / T 1408.1-1999 test method for electrical strength of solid insulating materials test at power frequency

GB / T 1409-1988 test method for relative permittivity and dielectric loss factor of solid insulating materials at power frequency, audio frequency and high frequency

GB / T 1410-1989 test method for volume resistivity and surface resistivity of solid insulating materials

GB / T 2951.2-1997 general test methods for insulating and sheathing materials of cables Part 1: General test methods

3. Product model

Peroxide crosslinked black polyethylene insulating material yjwo;

Silane crosslinked black polyethylene insulating material yjwg;

Irradiation crosslinked black polyethylene insulating material yjwf.

4 technical requirements

4.1 appearance

The insulating material shall be particles of uniform size and color, with a size of about 4mm in diameter and 3mm in height. Insulation consisting of single particles shall be black The base material of insulating material composed of multiple particles can be black or milky white, and the color of other materials is not specified. There shall be no obvious powder material in all bagged granular materials.

4.2 mechanical, physical and electrical properties

The mechanical, physical and electrical properties of insulating materials shall comply with the provisions in Table 1.

Table 1 mechanical, physical and electrical properties of insulating materials

Serial number

Test items

Company

Technical indicators

one

Tensile strength * * * small value

MPa

thirteen

two

Elongation at break * * * small value

three hundred

three

air

Thermal aging

Test conditions: thermal aging temperature

℃

135±2

Duration

one hundred and sixty-eight

The change rate of tensile strength shall not exceed

±20

The change rate of elongation at break shall not exceed

±20

four

Thermal extension

Test conditions: test temperature

℃

200±3

Load time

min

fifteen

Mechanical pressure

MPa

zero point two

Elongation under load * * * maximum

eighty

Long term deformation rate after cooling * * * large value

five

Volume resistivity at 20 ℃ * * * small value

Ω·m

5*1013

six

Dielectric strength * * * small value

MV/m

twenty-two

seven

Dielectric loss factor * * * maximum

zero point zero zero one

eight

Environmental stress cracking resistance F50 * * * small value

one thousand

nine

Embrittlement temperature * * * maximum

℃

-76

ten

Artificial weather aging resistance test

After 42 days of aging

The change rate of tensile strength shall not exceed

±30

The change rate of elongation at break shall not exceed

±30

42 days vs. 21 days

The change rate of tensile strength shall not exceed

±15

The change rate of elongation at break shall not exceed

±15

Note: * BLACK cross-linked polyethylene for overhead insulated cables with rated voltage of 1kV will not be assessed.

5 test method

5.1 appearance inspection

If required by the user, the manufacturer shall provide data such as extrusion temperature range, rheological properties and crosslinking process parameters of insulating materials. For peroxide crosslinked polyethylene insulation, the melt flow rate of the base material shall also be provided The melt flow rate of peroxide crosslinked polyethylene insulating base material shall be (2.0 ± 10.2) g / l0min.

5.2 sample preparation

a) Peroxide crosslinked polyethylene insulating material test piece is prepared by molding method The insulating material particles are plasticized and flaked on a plasticizer at (115 ± 2) ℃, and then preheated for 10min without pressure in a hydraulic press at (115-120) ℃ The crosslinking condition of the sample is (180 ± 2) ℃ × After 15min, the pressure of the hydraulic press shall be greater than 15MPa, and it shall be pressurized and cooled to room temperature. The test piece shall be flat and smooth, with uniform thickness and no bubbles.

b) Irradiated cross - linked polyethylene insulation test pieces were prepared by molding The insulating material particles shall be plasticized and flaked on a plasticizer at (150-155) ℃, and then preheated without pressure in a hydraulic press at (180 ± 2) ℃ for 6min, pressurized and heated for forming for 4min. The pressure of the hydraulic press shall be greater than 15MPa, pressurized and cooled to room temperature The test piece shall be flat and smooth, with uniform thickness and no bubbles. Then conduct irradiation crosslinking treatment (the irradiation dose shall be recommended by the manufacturer). The test piece shall remain flat after irradiation crosslinking.

c) The test piece of silane crosslinked polyethylene insulation material shall be prepared by extrusion method, and it is allowed to calender the test piece by pressing roller at the extrusion die. The test piece shall be flat and smooth with uniform thickness. Then immerse in a water bath with a temperature of (90-95) ℃ for (6-8) H. After crosslinking with warm water, the test piece shall remain flat.

Silane crosslinked polyethylene insulating material test piece can also be prepared by molding method. The prepared insulating material particles shall be plasticized and flaked on a plasticizer at (150-155) ℃, and then preheated without pressure in a hydraulic press at (180 ± 2) ℃ for 6min, pressurized and heated for forming for 4min. The pressure of the hydraulic press shall be greater than 15MPa, pressurized and cooled to room temperature. The test piece shall be flat and smooth, with uniform thickness and no bubbles. Then immerse in a water bath with a temperature of (90-95) ℃ for (6-8) H. After crosslinking with warm water, the test piece shall remain flat.

Extrusion method shall be used as the arbitration method for preparing black silane crosslinked polyethylene insulating material test piece.

The thickness of the test piece shall comply with the provisions of each test item.

5.3 tensile strength and elongation at break test

Tensile strength and elongation at break shall be tested according to GB / T 1040 The sample is an n-type dumbbell piece with a thickness of (1.0 ± 0.1) mm and a tensile speed of (250 ± 50) mm / min.

5.4 embrittlement temperature test

Embrittlement temperature shall be tested according to GB / T 5470 The thickness of the test piece shall be (1.6 ± 0.1) mm, 30 non notched samples shall be taken for each group, and the number of broken samples shall not be greater than 15.

5.5 air thermal aging test

Air thermal aging shall be tested according to 8.1 of GB / T 2951.2-1997. The test piece and tensile speed are the same as those specified in 6.3. The effective test piece shall not be less than 5. The test results shall be the arithmetic mean of all test pieces.

5.6 thermal elongation test

Thermal extension shall be in accordance with GB / T 2951 5. The test shall be conducted in accordance with Chapter 9 of 1997 The sample is type II dumbbell piece with a thickness of (1.0 ± 0.1) mm

5.7 volume resistivity test

The volume resistivity shall be tested according to GB / T 1410 The thickness of the test piece is (1.0 ± 0.1) mm. The test voltage is 1KV.

5.8 dielectric strength test

Dielectric strength shall be in accordance with GB / T 1408 1. Conduct the test as specified. Symmetrical electrodes shall be used with a diameter of 25 mm and an arc radius of 2.5 mm at the edge of the electrode 5mm。 The thickness of the test piece is (1.0 ± 0.1) mm. The dielectric constant of the insulating oil used for the test shall be close to 2.3 and have sufficient dielectric strength. The initial test voltage is zero. From 0 to 6kV, the voltage can be boosted at a faster rate. From 6kV to breakdown, the boost rate shall not be greater than 3KV / s.

5.9 dielectric loss factor test

The dielectric loss factor shall be tested according to the provisions of GB / T 1409.

5.10 environmental stress cracking resistance test

Environmental stress cracking resistance shall be tested according to Chapter 8 of GB / T 2951.8-1997.

5.11 weather resistance test

The weather resistance shall be tested according to Appendix A of GB 14049-1993 The specimen size and tensile speed shall be the same as those specified in 6.3.

6 inspection rules

6.1 each production batch is an inspection unit, each production batch is 20t, and less than 20t is still regarded as a batch.

6.2 each batch of products shall have the inspection certificate of the inspection department of the manufacturer.

6.3 items 1, 2, 4, 5 and 6 in Table 1 are routine test items. Items 3 and 7 in Table 1 are type test and sampling test items. Items 8, 9 and 10 in Table 1 are type test items.

6.4 routine test shall be conducted for each batch of products according to Article 7.3. Sampling test shall be conducted every three months. When the formula of raw materials and process conditions change, type test shall be carried out.

6.5 test samples shall be randomly selected from three packaging units of each batch of products. If any of the routine test items is unqualified, double sampling test shall be conducted for the unqualified test items. If there are still unqualified, the batch of products shall be determined as unqualified products.

7 marking, packaging, transportation and storage

7.1 YjW and yjwf insulating materials shall be moisture-proof packaging, with polyethylene film bag for the inner bag and polypropylene woven fabric / polyethylene / kraft paper composite bag for the outer bag. Yjwg insulating material shall be moisture-proof packaging, with aluminum foil / polyethylene composite film bag for the inner bag and polypropylene woven fabric / polyethylene / kraft paper composite bag for the outer bag. The net weight of each bag is (25 ± 0.2) kg. Other packaging methods agreed by the manufacturer and the user are allowed.

7.2 the packaging surface shall be marked with manufacturer's name, product name, model, batch number, manufacturing date, effective service life and moisture-proof mark. Product certificate and delivery test report shall be attached to the package.

7.3 insulating materials shall not be damaged by abnormal conditions such as sun, rain and water immersion during transportation.

7.4 insulating materials shall be stored in a clean, dry and ventilated warehouse, and the storage temperature shall not be less than 100C and not more than 35 ℃.

7.5 the storage period of black cross-linked insulating material shall not exceed six months from the date of production.

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Technical specification for black crosslinkable polyethylene insulating material for overhead insulated cable