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Specification

Enamelled Rectangular Copper and Aluminum Winding Wires for

Source:Original Editing:frank Time:2022-07-26 18:13
Inquiry:
In recent years, with the wide use of aluminum flat winding wire in the transformer industry, the performance comparison between enamelled rectangular copper wire and enamelled rectangular aluminum winding wire in dry-type distribution transformers has attracted more and more attention. Among them, the long-term creep behavior of copper flat winding wire and aluminum flat winding wire is one of the important indicators of reliability and stability of copper and aluminum transformers. The creep and conventional properties of enamelled rectangular copper and aluminum winding wires for power transformers are tested, and the reliability of copper and aluminum flat winding wires is evaluated and analyzed, which plays a certain reference role for transformer manufacturers to understand the differences between copper and aluminum transformers and select reliable materials and technologies.
 
According to gb1094.11-2007 power transformers Part 11: dry type transformers, gb/t1094.12-2013 power transformers Part 12: load guide for dry type power transformers and gb1094.5-2008 power transformers Part 5: ability to withstand short circuit doi:10.16105/ j.cnki.dxdl.2021.06.009 and actual work experience, it is recommended to set the withstand temperature of the creep test of enameled aluminum flat winding wire to 160 ℃. Therefore, the test temperature of the creep performance comparison test of copper flat winding wire and aluminum flat winding wire is set at 160 ℃, and the withstand stress is 35 ~ 70MPa.
 
 
 
Creep test shall be carried out according to gb/t2039-2012 uniaxial tensile creep test method for metallic materials [7] and gb/t4338-2006 high temperature tensile test method for metallic materials [8]. The main test steps are as follows: ① after putting the test line into the heating furnace, apply 3N offset tension (at room temperature) on it to straighten the test line without plastic deformation; ② Use the self weight of the lever system to apply tensile load on the test line; ③ After applying the required tensile load on the test line, the temperature in the furnace rises to the required test temperature, and the test temperature and load are kept constant during the creep test until the end of the test. The routine performance test of samples before and after creep test shall refer to gb/t7095.1-2008 enamelled copper flat winding wires Part 1: general provisions, gb/t7095.4-2008 enamelled copper flat winding wires Part 4: grade 180 polyesterimide enamelled copper flat wires, iec60317-0-9:2015 standard for special winding wires Part 0-9: General Provisions for enamelled aluminum flat wires Iec60317-74:2018 standard for special winding wires Part 74: polyesterimide enamelled aluminum flat wire of class 180 and other standards.

 
When the creep test temperature is 160 ℃, through the comparative study of the stress resistance, creep stage, surface morphology, conductor size and electrical properties of enamelled rectangular copper and aluminum winding wires, the following conclusions can be obtained:
 
(1) When the creep test temperature is 160 ℃, the withstand stress of aluminum flat winding wire is significantly lower than that of copper flat winding wire;
(2) When the creep test temperature is 160 ℃ and the withstand stress is 35MPa, the creep behavior of aluminum flat winding wire is more obvious than that of copper flat winding wire;
(3) The conductor size test results show that under the same test conditions, the section size shrinkage of aluminum flat winding wire sample is more obvious than that of copper flat winding wire sample;
(4) The results of DC resistivity calculation show that under the same test conditions, the conductivity degradation of aluminum flat winding wire is more obvious than that of copper flat winding wire.
It can be inferred that under the same creep test conditions, the creep resistance of enamelled rectangular aluminum winding wires is significantly inferior to that of enamelled rectangular copper winding wires.