In the power system, the transformer is the core equipment for power conversion and distribution, and its operational stability is directly related to the safety of the entire power grid. Partial Discharge (PD for short) is an important signal of transformer insulation degradation and one of the main hidden dangers leading to transformer failures. Especially for equipment widely used in industrial and commercial scenarios such as dry type distribution transformer and 150 kva dry type transformer, understanding the basic knowledge of partial discharge is crucial. This article will detailedly explain the definition, causes, hazards, detection methods and preventive measures of transformer partial discharge, helping relevant practitioners scientifically maintain equipment and extend the service life of transformers.
JINSHANMEN TECHNOLOGY CO., LTD, as a professional manufacturer of power transmission and distribution equipment, has been deeply engaged in the transformer field for many years. The company mainly produces oil immersed power transformers, dry-type power transformers, oil immersed three-dimensional coiled power transformers, dry-type three-dimensional coiled power transformers, mining explosion-proof dry-type transformers, mining explosion-proof mobile substations, amorphous alloy power transformers, on load capacity regulating power transformers, locomotive dry-type transformers, as well as prefabricated substations, modular substations, wind energy box type substations, high and low voltage switchgear and other transmission and distribution equipment. With exquisite production technology and strict quality control, the company effectively reduces the partial discharge hidden dangers of 150 kva dry type transformer and dry type distribution transformer, providing reliable power transmission and distribution solutions for global customers.
I. What is Transformer Partial Discharge?
Partial Discharge (PD for short) refers to the phenomenon of local repeated breakdown and extinction that occurs at some insulation weak points in the transformer insulation structure under a certain applied voltage, but does not immediately form a complete insulation breakdown. This kind of discharge limited to local positions (weak points) of the insulation is called partial discharge.
The amount of partial discharge is relatively weak, which is difficult to perceive by human intuition and can only be captured and quantified with professional measuring equipment. For 150 kva dry type transformer, which is often used in small and medium-sized power distribution scenarios, its insulation structure is relatively compact. Once partial discharge occurs, if not handled in time, it is easy to accelerate insulation aging and affect the normal operation of the equipment; as a key equipment in the power distribution system, the control of partial discharge of dry type distribution transformer is the core link to ensure power distribution safety.
II. Causes of Transformer Partial Discharge
The causes of transformer partial discharge are complex, involving insulation materials, operation process, installation technology and other aspects, which can be mainly divided into the following three categories. Among them, some causes are more prominent in the production and operation of dry type distribution transformer and 150 kva dry type transformer:
1. Problems with Insulation Materials and Structure Itself
(1)Defects such as bubbles, impurities and cracks in insulation materials will directly affect the insulation performance of materials and become "hidden danger points" of partial discharge. Especially for the insulation materials of dry-type transformers, if the purity is not up to standard during the production process, the probability of defects will increase significantly.
(2)The dielectric constant of bubbles is usually lower than that of insulators, so the electric field strength borne by bubbles is much higher than that of adjacent insulation materials, which is more likely to be broken down, thus causing discharge. This problem is particularly common in the winding casting process of 150 kva dry type transformer. If the casting process is not in place, bubbles are easy to remain.
(3)Unreasonable design of insulation structure. In the insulation structure design of dry type distribution transformer and 150 kva dry type transformer, if the electric field strength between layers or turns is too high, it will lead to local electric field concentration, and then cause discharge.
(4)Insulators, metal bodies and other parts in the transformer often have some sharp corners and burrs, which will lead to the concentration of electric field strength at specific positions, thus causing partial discharge. In the process of lead wire production of dry-type transformers, if the process is not refined, burrs are easy to generate, which become the source of discharge.
2. Influences in the Operation Process
(1)Long-term operation and load changes will lead to the aging and wear of insulation materials inside the transformer, losing their original insulation performance, and easily causing partial discharge. For dry type distribution transformer that has been operating at full load for a long time, this aging phenomenon is more obvious.
(2)Overvoltage is one of the main causes of transformer partial discharge. Overvoltage in the power system may be caused by external factors (such as lightning strikes) or internal factors (such as switch operation). When the voltage exceeds the breakdown voltage of the material, partial discharge will occur.
3. Problems with Installation and Technology
(1)Imperfect production technology, such as poor vacuum control in the drying process, insufficient drying time and temperature, leading to residual gas in the coil, which is also a common inducement of partial discharge in 150 kva dry type transformer.
(2)The transformer insulation may be damaged during installation, or the water content of insulation materials exceeds the standard due to long idle time, and the whole body of the transformer is damp, which will affect the partial discharge capacity, especially for the insulation performance of dry type distribution transformer.
(3)Poor winding casting technology and assembly technology (such as burrs in the production of high and low voltage leads or improper distance) will also increase the risk of partial discharge. In the production process, JINSHANMEN TECHNOLOGY CO., LTD strictly controls every process link, effectively avoiding the above problems and ensuring product quality.
III. Hazards of Partial Discharge
Although the partial discharge of the transformer has a small range, small energy and short time, its long-term existence will bring serious hazards, which are mainly reflected in the damage to insulation materials, especially for dry type distribution transformer and 150 kva dry type transformer:
First, partial discharge directly bombards the insulation, causing local insulation damage, which may gradually lead to insulation breakdown. The electrolysis effect produced by discharge will generate active gases such as ozone and nitric oxide, corrode local insulation, and gradually cause insulation damage. Long-term accumulation will lead to equipment failure.
Second, the heat generated by partial discharge will increase the local temperature of the medium, even carbonize it, further accelerate insulation aging and shorten the service life of the transformer. For small and medium-sized equipment such as 150 kva dry type transformer, the repair difficulty is large after insulation carbonization, and parts often need to be replaced as a whole, increasing maintenance costs.
IV. Detection Methods of Partial Discharge
The detection of partial discharge is the key to timely find transformer hidden dangers. The commonly used detection methods mainly include electrical measurement method, ultrasonic measurement method, chemical measurement method, etc. These methods are applicable to various types of transformers, including dry type distribution transformer and 150 kva dry type transformer:
1. Electrical measurement method: Use oscilloscope, partial discharge instrument or radio interference instrument to find the discharge waveform or radio interference degree, which can accurately quantify the partial discharge capacity and is the most widely used detection method at present.
2. Ultrasonic measurement method: Detect the ultrasonic wave generated in the discharge and convert the sound wave into electrical signal for analysis, which can realize the accurate positioning of the discharge position, facilitating targeted treatment of hidden dangers.
3. Chemical measurement method: Detect the content of various gases dissolved in oil and their change rules, usually called "chromatographic analysis", which is applicable to oil-immersed transformers. For dry-type transformers, it can be detected by combining other auxiliary methods to ensure detection accuracy.
V. Preventive Measures of Partial Discharge
To avoid the hazards of partial discharge and extend the service life of transformers, especially to ensure the stable operation of dry type distribution transformer and 150 kva dry type transformer, the following preventive measures can be taken:
(1)Select insulation materials with good insulation performance to reduce the hidden dangers of partial discharge from the source. When producing dry-type transformers, JINSHANMEN TECHNOLOGY CO., LTD selects high-quality insulation materials and strictly controls the material purity, effectively improving the insulation performance of products.
(2)Regularly inspect and maintain the insulation materials of the transformer, and timely replace the aging and severely worn parts. Especially for dry type distribution transformer that has been operating for a long time, regular maintenance can effectively prevent partial discharge.
(3)Install overvoltage protection devices to timely detect and suppress overvoltage phenomena, avoiding discharge caused by overvoltage.
(4)Install temperature monitoring devices to regularly detect the surface temperature changes of the transformer, timely find the temperature abnormalities caused by partial discharge, and avoid the expansion of hidden dangers.
Summary: Partial discharge is an "early warning signal" of transformer insulation degradation. Especially for 150 kva dry type transformer and dry type distribution transformer, doing a good job in the detection and prevention of partial discharge is the key to ensuring the stable operation of equipment and reducing the risk of failure. With professional production technology and strict quality control, JINSHANMEN TECHNOLOGY CO., LTD effectively controls the hidden dangers of partial discharge in the production of various transformers, providing safe and reliable power transmission and distribution equipment and related technical support for global customers.