Introduction
transformer
A device that changes voltage, current, or phase by coupling a magnetic circuit
Why learn Transformers?
Transformers are also known as stationary AC motors

In March, our indian sales manager lead a team to attend the MIDDLE EAST ELECTRICITY Exhibition. 
During the exhibition, we met different customers in the mid-east countries. Introduce our latest equipment-AI Robot Lamination Processing Centre to them. 
We are confidence that our latest model can lead the market!

Oil-immersed transformers have the characteristics of good heat dissipation, low loss, large capacity and low price. At present, most of the power transformers running on the grid are oil-immersed transformers, of which more than 80% are cooled by natural oil circulation. It is a commonly used cooling structure to set a guide plate in the coil of a natural oil circulation transformer. This paper focuses on analyzing the structure, operation and maintenance of oil-immersed power transformers, and specifically analyzes the oil system of oil-immersed power transformers, and briefly analyzes the faults of oil-immersed power transformers. Hope to increase understanding and analysis of my country's oil-immersed power transformers.

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.

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.

01 Inrush current
When a transformer is first energized, a phenomenon called magnetizing inrush occurs. Although inrush currents are generally not as disruptive as fault currents, the duration of magnetizing inrush currents is on the order of seconds (compared to periods with fault currents).

Corresponding protection devices shall be installed for the short-circuit faults of the transformer lead wires, bushings and internals, and shall meet the following requirements: 
1) The single-running transformer of 10MVA and above and the parallel running transformer of 6.3MVA and above should be equipped with longitudinal differential protection. Important transformers with 6.3MVA and below operating independently can also be equipped with longitudinal differential protection.
2) Transformers below 10MVA can be equipped with current quick-break protection and overcurrent protection. For transformers of 2MVA and above, when the current quick-break sensitivity coefficient does not meet the requirements, longitudinal differential protection should be installed. 
3) 0.4MVA and above, the primary voltage is 10kV and below, and the coil is a transformer with a delta-star connection, and a two-phase three-relay type overcurrent protection can be used.
4) The various protection devices specified in this article shall operate to disconnect the circuit breakers on each side of the transformer.

The power loss of the transformer is divided into iron loss and copper loss. Iron loss is also called no-load loss, which is its fixed loss. It is actually the loss generated by the iron core (also called iron core loss, and copper loss is also called load loss).

The winding and iron core of the transformer are the main components for transmitting and transforming electromagnetic energy, and ensuring their safe operation is a problem that people are concerned about. Statistics show that the fault is caused by the iron core problem, accounting for the third place in the total transformer accident. The manufacturing department has paid attention to the defects of the transformer core, and has made technical improvements in the metal hose and stainless steel hose grounding monitoring of the iron core and ensuring a little grounding.

This article mainly counts 7 types of fault judgment methods and solution analysis of dry-type transformer noise. If there is any error or omission, please point it out in the comment area.
Analysis of 7 types of fault judgment methods and solutions for dry-type transformer noise
➢Resonance problems of fans, casings and other components
➢Installation problems
➢Influence of installation environment
➢The problem of vibration of busbar bridge
➢Transformer core resonates by itself.
➢Transformer coil self-resonance
➢The problem of the nature of the load

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:

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: