All the standards referred to the most current issue, including all amendment supplements. as of the date of the bid.

Transcription

1 1. Scope This specification defines the methods, the procedures and the requirements to verify the cables manufactured according to I.E.C. Specifications NPS Standards All the standards referred to the most current issue, including all amendment supplements. as of the date of the bid. Relevant standards: IEC Publication 60060: High Voltage Test Techniques. Israel standard 65 (Identified to IEC Publication 60228: Conductors of Insulated Cables ). IEC Publication 60230: Impulse Test on Cables and their Accessories. Israel standard 1516 (Identified to IEC ) "Extruded Solid Insulated power cable for rated voltages up to 30kV" HD Publication 620 part 5C: Cross linked PE Insulated Cables. DIN VDE : Additional test method. IEC Publication 60811, Common test methods for insulating and sheathing materials of electric cables. IEC Publication : Test methods for partial discharge measurements on lengths of extruded power cables. American Standard ICEA S66524 In case of differences between the present specification and the above the mentioned 3. Requirements for Test Certificates The following information is necessary on each test certificate: The name of the cable factory; The name and address of the testing laboratory (if the testing laboratory does not belong to the cable factory); The test certificate serial number; The certificate issue date;

2 Test reports of the special test shall specify the batch number of the cables to which they pertain; Manufacturer s evaluation of the test results; A signature of the person responsible for tests and his position. The test certificate should contain results for each test according to the test requirements with references to appropriate Clauses and SubClauses of Standards and Specifications. 4. Test Conditions 4.1. Ambient Temperature Test shall be made at an ambient temperature of C Frequency and Waveform of Power Frequency Test Voltages The frequency of the alternating test voltages shall be in the range 49 Hz to 61 Hz. The waveform shall be substantially sinusoidal. The values quoted are r.m.s values Waveform of Impulse Test Voltage In accordance with IEC Publication 60230, the impulse wave shall have a virtual front time between 1 s and 5 s and in other respects shall be in accordance with IEC Publication

3 5. Rounding of the test results The test results shall be rounded in accordance with Appendix C of IEC Publication 60502, part Routine tests 6.1. The routine tests shall be carried out on each manufactured length of the cable on the delivery drum. The routine tests requirements are: a) Measurement of the conductor electrical resistance (SubClause 6.2); b) Partial discharge test (SubClause 6.3); c) Measurement of the metallic screen electrical resistance (SubClause 6.4); d) Highvoltage test (SubClause 6.5); e) Outer protective sheath spark test (SubClause 6.6); f) Outer protective sheath integrity visual inspection (SubClause 6.7) Measurement of the conductor electrical resistance a) The complete cable length shall be kept in the test room, which shall be maintained at a reasonable constant temperature for at least 12 hours before the measurement. The measured value of resistance shall be corrected to the temperature of 20 C and 1 km length in accordance with Clause 6 of IEC Publication b) The dc. resistance of the conductor at 20 C shall not exceed the appropriate maximum value specified in IEC Publication Partial Discharge Test a) The partial discharge test shall be carried out in accordance with IEC Publication b) The magnitude of the partial discharge at 2U 0 shall not exceed 5 pc.

4 6.4. Measurement of the Metallic Screen Electrical Resistance The dc. resistance of the metallic screen at 20 C shall not exceed the appropriate maximum value specified in I.E.C. Specification NPS A.C. High Voltage Test Test Procedure The test voltage shall be applied for 5 minutes between the conductor and the metallic screen Test voltage The test voltage shall be 3.5U Requirement No breakdown of the insulation shall occur Outer Protective Sheath Spark Test a) Test Procedure The cable shall be passed through the electrode (s) while the test voltage is applied between the electrode (s) and the grounded cable metallic screen. The test voltage shall be of 10 kv ac. minimum while the dwell time of the cable in the region of the test electrodes shall be not less than 0.15 s in accordance with the American standard ICEA S66524, NEMA WC 7. b) No breakdown of the outer protective sheath shall occur Outer protective sheath integrity visual inspection a) The test shall be carried out by visual inspection during the final stage of the cable manufacturing or during the cable rewinding onto the delivery drum.

5 b) The sheath has to be reasonably round, its surface has to be smooth, without visible irregularities, cracks, inflates, dents, hollows and so on. 7. Special Tests 7.1. General The special tests shall be performed on the cable samples taken from the cable lengths on the drums belonging to the batches mentioned in SubClause 7.2. The special tests requirements are: a) Conductor Examination (SubClause 7.4); b) Check of Dimensions (SubClause 7.5); c) High Voltage Test (SubClause 7.6); d) Hot Set Test (SubClause 7.7); e) Insulation Imperfection discovering and Measurements (SubClause 7.8).

6 7.2. Sampling for Special Tests Sampling of the cable for the Special Test shall be performed according to the following table: *) Definition Total number of drums in the cable batches *) Repetition of Tests Cables shall be considered of the same batch if they are manufactured continuously without interruption from the same batch of insulation material with no alteration in the setting of the manufacturing machines. If one of the samples fails in any of the special tests, the manufacturer shall immediately inform the purchaser. The decision concerning further sampling and testing shall then be the prerogative of the purchaser, taking into consideration the failure cause. Above up to and including etc. Number of cable drums from which samples shall be tested etc Conductor Examination The conductor construction shall comply with the requirements of I.E.C specifications and shall be examined by visual inspection and by measurement when practicable Check of Dimensions

7 The dimensions of the cables shall be measured as specified in Table 1 of this specification. The test result shall comply with the requirements given in the relevant clauses of NPS361 Specifications. Table 1 Test methods for cable dimensions 1. Conductor screen (HD605, sub clause ) The smallest thickness Irregularities 2. Insulation ((IEC Publication and ) The average thickness The smallest thickness Difference between maximum and minimum value of thickness Diameter over insulation 3. Insulation screen (HD605, sub clause ) The smallest thickness The maximum thickness The difference between the lowest and the highest value over the insulation screen 4. Metallic screen The wire diameter and the tape thickness shall be measured by means of a micrometer having two flat noses to the accuracy of ±0.01 mm. The average copper tape thickness The wire diameter The calculated crosssectional area of the screen

8 Table 1 (continued) Tests 5. Outer protective sheath (IEC Publication and ) The average thickness The smallest thickness 6. Cable outer diameter ((IEC Publication ) The outer diameter, maximum The outer diameter, minimum 7.6. High Voltage Test a) Sampling: The sample shall be a piece of the completed cable at least 5 m in length between the test accessories. b) Procedure: A power frequency test voltage shall be applied for 4 h at a room temperature between the conductor and the metallic screen. c) Test Voltage: The test voltage shall be 4U 0. d) Requirement: 7.7 Hot Set Test No breakdown of the insulation shall occur. The sampling and test procedure shall be carried out in accordance with the IEC Publication , using conditions and requirements given in Table 3 of this Specification.

9 7.7. Imperfection Discovering and Measurement a) The test procedure shall be as follows: The test specimen with the outer semiconducting layer removed shall be placed in a heated air convection oven at the temperature of 80ºC for two hours. Then the test specimen shall be placed in a glass tube filled with hot silicone oil at the temperature of 130ºC or, if necessary, higher up to about 150ºC, until the XLPE insulation becomes fully transparent. The test specimen shall be then examined with the naked eye with the help of lighting and recognized imperfections or irregularities shall be marked on the surface of the specimen. Then the specimen shall be cooled to a room temperature. To enable the measurement of the ascertained imperfections the test specimen shall be cut at the marked points, in thin slices. b) Requirements The imperfections found with the above mentioned procedure shall answer the following requirements: they are only permitted as separate cases; The imperfections with the largest size less than 0.05 mm should not be taken into account; The imperfections with the largest size more than 0.2 mm are not permitted. In the presence of imperfections with the largest size in the range from 0.05 mm to 0.2 mm, the repeated test should be performed; in this test any imperfections with largest size more than 0.05 mm should not be found.

10 8. Type Tests 8.1. General a) The tests shall be carried out on samples of the cable of the same type to be manufactured and supplied. The manufacturer shall submit to the bid type test certificates according to I.E.C Specifications NPS361. b) The type tests shall comprise of the electrical tests on completed cable specified in SubClause 8.2 and the nonelectrical test of the cable components specified in SubClause Electrical Type Tests General a) The electrical type tests shall be performed on samples of completed cable, at least 10 m in length between the test accessories. b) With the exceptions of the provisions of SubClause all the tests listed in SubClause shall be applied successively to the same sample Sequence of Tests The normal sequence of tests shall be: a) Partial discharge test; b) Bending test plus the partial discharge test; c) Tan measurement as a function of the temperature; d) Heating cycle test plus the partial discharge test; e) Impulse withstand test followed by the power frequency voltage test; f) Highvoltage alternating current test; g) Measurements of electric resistivity of the semiconducting layers.

11 Special Provisions a) Test (c and d) may be carried out on different samples from the sample used for the normal sequence of tests listed in SubClause b) A new sample may be taken for test g), provided this test sample is submitted previously to test b) and e) listed in SubClause Test methods and requirements for the electrical type tests are given in Table 2 of this Specification. Table 2 1. Partial Discharge Test (IEC Publication, subclause ) Tests Units Requirements 1.1 Test voltage 1.2 Partial discharge, maximum kv pc 2U Bending Test (IEC Publication, sub clause ) 2.1 Diameter of test cylinder 20 (dd) 5, where: D actual external diameter of the cable; d actual diameter of the cable conductor; 2.2 Number of test cycles 2.3 Partial discharges, maximum mm mm pc Tan measurement as a function of the temperature (IEC Publication. Sub clause ) 3.1 Test voltage 3.2 Tan at ambient temperature, maximum Tan at (90 2) C, maximum kv Table 2 (continued) Tests Units Requirements

12 4. Heating cycle test (IEC Publication. Sub clause ) 4.1 Temperature at the test, maximum 4.2 Time of heating, minimum 4.3 Time of natural cooling, minimum 4.4 Number of heating/cooling cycles 4.5 Partial discharges, maximum C h h pc Impulse withstand test (IEC Publication , SubClause ) 5.1 Conductor temperature 5.2 Impulse form 5.3 Impulse test voltage 5.4 Number of impulses C s kv 90 (5 10) C 1.2/ pos. 10 neg. 6. A.C. voltage test (IEC Publication , SubClause ) 6.1 Test voltage 6.2 Time of the test voltage application kv min 3.5 U High voltage test for 4 h (IEC Publication , SubClause ) 7.1 Test voltage 7.2 Time of the test voltage application kv h 4 U 0 4 Table 2 (continued) Tests Units Requirements 8. Measurements of electric resistivity of the semiconducting layers (IEC Publication Appendix D) 8.1 Resistivity of the conductor screen at 90 C, maximum 8.2 Resistivity of the insulation screen at 90 C, maximum Ohm m Ohm m

13 8.3 NonElectrical Type Test The nonelectrical type tests are listed in the following table: Tests XLPE Insulation ST7 Outer Sheath 1. Check of the cable construction 2. Mechanical properties (tensile strength and elongation): Before aging After aging in an air oven After aging of pieces of the complete cable 3. Hot set test 4. Pressure test at a high temperature 5. Carbon black content 6. Shrinkage test 7. Test of longitudinal water tightness in the screen area

14 8.3.1 Check of the Cable Construction Check of dimensions and the examination of the conductor shall be carried out in accordance with the requirements of SubClause 7.4 and Test methods and requirements for the nonelectrical type tests are given in Table 3 of this Specification Test of longitudinal watertightness in the screen area a) Sample The test shall be made on a 3 m long piece of the cable cut from the sample undergone the bending test described in Clause 2 of Table 2 without additional partial discharge test. b) Test Method The test shall be carried out in accordance with the method described in Appendix F of IEC Publication c) Evaluation During the period of testing no water shall emerge from the ends of the test piece

15 Table 3 Tests Units XLPE Insulation ST7 Outer Sheath 1 Mechanical Properties 1.1 Before ageing (IEC Publication Clause 9) Tensile strength, minimum Elongation at break, minimum N/mm After ageing of test pieces and pieces of complete cable (IEC Publication , Clause 8) Treatment: Temperature for the test pieces; for the complete cable Duration for the test pieces; for the complete cable C C days days Tensile strength: Variation maximum Elongation on break: Residual value, min. 25 variation, maximum Pressure Test at High Temperature (IEC Publication , Clause 8) 2.1 Test temperature 2.2 Time under load 2.3 Depth of indentation, maximum C hours Table 3 (continued) Tests Units XLPE Insulation ST7 Outer Sheath

16 3. Hot set test (IEC Publication , Clause 9). 3.1 Treatment: Air temperature Time under load Mechanical stress 3.2 Elongation under load, maximum C min N/mm Permanent elongation after cooling, maximum Shrinkage test (IEC Publication , Clause 10) 4.1 Treatment: Temperature Duration 4.2 Heating cycles 4.3 Permissible shrinkage, maximum C hours Carbon black content (IEC Publication , Clause 11) Qualification tests Qualification tests are intended to demonstrate the capability of the manufacturer to supply high quality cable with the desired performance characteristics. The Qualification tests shall be performed optionally on samples of a completed cable according to the requirements of the HD Publication 620 part 5c, clause 6.6 or a similar national standard upon agreement between the manufacturer and the purchaser. 9. Acceptance test The acceptance tests shall be performed according to I.E.C. Specification No. S2000/3/7.10.