Method for detecting winding material of three-phase winding device based on thermocouple principle
A three-phase winding and phase winding technology, applied in the direction of material resistance, can solve problems such as unscientific judgment, large difference in transformer volume, and increased volume of three-phase winding equipment, achieving simple operation, strong anti-interference ability, and detection. handy effect
Active Publication Date: 2013-08-21
HUAZHONG UNIV OF SCI & TECH
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Problems solved by technology
[0003] The electrical conductivity of aluminum is lower than that of copper. In order to keep the end resistance of aluminum windings the same as that of copper windings, it is necessary to increase the cross-sectional area of aluminum wires, which will eventually lead to an increase in the volume of three-phase winding equipment. However, the volume of transformers of the same type from different suppliers varies greatly. Large, it is unscientific to judge the winding material only based on the volume
There is a significant difference between the conductivity of aluminum and copper as a function of temperature. The whole three-phase winding equipment can be heated, and the winding material can be determined by measuring the change curve of winding resistance with temperature. However, this method requires large-scale heating equipment, and the test can Operability is not strong
[0004] At present, there is no simple and effective method for non-destructive testing of the winding materials of three-phase winding equipment
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[0029] In order to make the content of the present invention more clear and intuitive, the low-voltage winding materials of two S11-M-400 / 10 oil-immersed three-phase aluminum winding and copper winding transformers of the same model were tested respectively. The test wiring is as follows: image 3 shown.
[0030] In the test, the voltage is applied to the high-voltage side, and a single-phase short circuit is used to induce a large current on the low-voltage side to realize the heating of the low-voltage winding. On the high-voltage side of the transformer, the AC phase is connected to a variable-amplitude power-frequency AC voltage through a voltage regulator. On the low-voltage side, a copper rod with a large enough cross-sectional area short-circuits the a-phase winding, and the a-phase heats up. Before pressurization, detect the DC voltage between the two phases on the low-voltage side of the two test samples. During the test, raise the voltage regulator to a certain volta...
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The invention provides a nondestructive detection method of a three-phase winding material based on thermocouple principle, belonging to the technical field of medium and large-sized electric power three-phase winding devices in an electrical power system. The method concretely comprises the steps of: respectively connecting outgoing lines of all phases of windings of a three-phase winding device with copper conductive rods; carrying out asymmetrical heating on a three-phase winding by electrifying the copper conductive rods through power supplies arranged outside the copper conductive rods, so that temperature difference is generated between one phase of winding and the other two phases of windings; at the time, interrupting the current and collecting the direct current (DC) voltage between the two phases with temperature difference; if the collected DC voltage shows that parasitic thermoelectric potential is not generated, judging the winding material of a transformer is copper; and if the collected DC voltage shows that parasitic thermoelectric potential is generated and direct current voltage collected after the current is interrupted is gradually vanished, judging the winding material of the transformer is aluminum (or other non-copper materials). The method can effectively detect the winding material, and is simple to operate, convenient for detection, high in accuracy and nondestructive to electrical equipment.
Description
technical field [0001] The invention relates to the technical field of large-scale power three-phase winding equipment in electric power systems, and in particular to a method for detecting winding materials of three-phase winding equipment. Background technique [0002] Large-scale power three-phase winding equipment (transformers, motors, reactors) is the most critical equipment in the power system, and its quality directly affects the safety and reliability of power grid power supply, while the reliability of three-phase winding equipment depends largely on the winding used Material. The winding material of three-phase winding equipment is generally copper or aluminum, and copper and aluminum materials have large differences in performance parameters and market prices. The mechanical properties and temperature characteristics of aluminum materials are not as good as copper, and the short-circuit resistance of aluminum three-phase winding equipment is worse than that of c...
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IPC IPC(8): G01N27/14
Inventor 张丹丹周志强武兰民王金虎丁漫江周吴
Owner HUAZHONG UNIV OF SCI & TECH