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The transformer is a static device in continuous operation, which is relatively reliable in operation and has less chance of failure. However, since most of the transformers are installed outdoors, and are affected by the load during operation and the short-circuit fault of the power system, various faults and abnormal situations inevitably occur during operation.

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No-load test: Apply the rated voltage of the sine wave rated frequency from a certain winding of the transformer (generally from the secondary low-voltage side), and open the other windings to measure the no-load current and no-load loss. If the test conditions are limited and the power supply voltage cannot reach the rated voltage, the test can be performed under non-rated voltage conditions. This test method has a large error and is generally only used to check whether the transformer is faulty. Only the test voltage reaches more than 80% of the rated voltage. can be used to test the no-load loss.

Transformer faults can be divided into internal faults and external faults.Transformer internal faults refer to the faults that occur in the transformer oil tank, including phase-to-phase short circuit of each winding, inter-turn short circuit of winding, short circuit fault between winding and iron core, single-phase grounding fault of single-phase winding or lead-out wire passing through the shell, winding disconnection fault, etc. Transformer external faults refer to various faults that occur on the external insulating bushing of the transformer oil tank and its lead-out wires, including single-phase grounding short-circuits and phase-to-phase short-circuits between lead-out wires caused by flashover or broken insulating bushings.

1. Why should the iron core of the transformer be grounded?Transformer core grounding is for safety and electromagnetic compatibility considerations.On the one hand, grounding the transformer core prevents contact voltages caused by ground faults, which can pose a shock hazard to humans. Because when a ground fault occurs on one side of the transformer, the iron core on the other side may have a voltage in contact with the earth. If it is not grounded, this voltage cannot be released.On the other hand, grounding the transformer core can also reduce electromagnetic radiation interference, especially for radio equipment and communication systems. This is because the current will generate a magnetic field in the iron core. If the iron core is not grounded, this magnetic field may leak into the surrounding environment and interfere with the normal operation of other equipment.In conclusion, grounding the transformer core is a protective measure against shock hazards and electromagnetic interference.

With the development of the power system in the direction of energy saving and intelligence, the quality, reliability and performance requirements of power transmission and distribution and control equipment are gradually improved. In order to adapt and meet market demand, manufacturers of power transmission and distribution and control equipment continue to improve Product structure, improving product performance, and strengthening independent R&D and exploration of new technologies, new industries, new formats, and new models. Its development presents the following trends:

Electrical Technology Q&A (1.1)What is the basic content of Kirchhoff's law?2. What is skin effect?3. What are the concepts and characteristics of parallel resonance?4. How are eddies created? What is eddy current loss?5.What is the transition process? What causes the transition process?6. What is the superposition principle?

To deal with transformer short circuit accident in daily operation, it is necessary to find out the essence of the problem through inspection and test. When the transformer suffers from sudden short circuit, the high and low voltage sides will be subject to large short circuit current. In the short time when the circuit breaker has no time to disconnect, the electric force generated by the short circuit current, which is proportional to the square of the current, will act on the transformer winding. This electric force can be divided into radial force and axial force. In case of short circuit, the radial force acting on the winding will make the HV winding subject to tension and the LV winding subject to pressure. Since the winding is circular, the circular object is more easily deformed under pressure than under tension, so the low-voltage winding is more easily deformed. The axial force generated in case of sudden short circuit compresses the winding and causes axial displacement of high and low voltage windings. The axial force also acts on the iron core and clamps. Therefore, when the transformer suffers from sudden short circuit, the low-voltage winding and balance winding are most likely to be deformed, followed by the high-voltage winding, iron core and clamp. In addition to checking the main windings, iron cores, clamps and other parts after the transformer short-circuit accident, a series of related problems should also be paid attention to during the handling process:

This paper analyzes the harm and cause of unbalance of three-phase load of distribution transformer, and puts forward some measures to solve the unbalance.  

During construction, dry transformer and oil transformer can be selected according to the space. Oil transformer can be selected when the space is large, and dry transformer can be selected when the space is crowded.

In the past year, I thank all new and old customers for their trust and support in CANWIN. As the Chinese Lunar New Year approaches，CANWIN wishes all new and old customers good luck, good health and happy family! In the new year, we will continue to bring more and better transformers and intelligent equipment and better pre-sale and after-sales services to new and old customers at home and abroad, and create more value for the society! Let's work together for a better future!

[Good News] Guangdong Canwin Intelligent Equipment Manufacturing Co., LTD., founded in 2002, won the 2020 China Science and Technology Progress Award and Guangdong Provincial Technology Invention Award for its key Technology and Equipment for Precision and Efficient Cutting of High-end Metal Plate and Belt. In addition, the push and pull material technology applied by Guangdong Canwin for cutting silicon steel sheet material below 0.18mm in 2014 has won the national invention patent [Patent Number: CN103990731A], which has become the standard configuration of thin plate shear transverse shear line in the electrical equipment industry. Recently, Guangdong Canwin launched another subversive product, double robot six-station automatic laminating horizontal cutting line. The product is the No.1unit in China, but also the No.1unit in the world. Its key technology is to grab five pieces at a time (double robot is equivalent to ten pieces at a time), can fold six transformer cores. [has applied for a number of patents] This technology ends up the history of the traditional transverse cutting line only cutting function without stacking function, and is the turning point for leading the technology take-off of the global electrical equipment industry!