In the power system, transmission insulation is one of the key links to ensure the safe operation of high-voltage equipment. Transmission insulation materials usually include insulators, insulating oil and related auxiliary materials, which jointly undertake the tasks of isolating high voltage, preventing surges and protecting electrical equipment. However, due to the complex working environment of transmission insulation materials and long-term exposure to high loads and harsh natural conditions, their performance is easily affected by external factors. Therefore, it is crucial to regularly inspect and conditionally assess transmission insulation.
We will introduce the actual inspection methods, condition assessment standards and common troubleshooting measures for transmission insulation in detail from the perspective of practical operation, aiming to provide a reference for power system maintenance personnel.
Practical inspection of transmission insulation
Appearance inspection
Insulator integrity: First, check whether the appearance of the transmission insulation material is intact. If there are cracks, wear or damage on the surface of the insulator, it may affect its insulation performance.
Insulating oil layer status: For equipment using insulating oil, check whether the oil layer is aging, stratified or leaking. The oil layer status directly affects the insulation performance and equipment life.
Electrical characteristic test
Insulation resistance test: According to relevant standards, the insulation resistance test of transmission insulation materials should be carried out regularly. Under normal circumstances, the insulation resistance value should meet the specified requirements.
Dielectric loss ratio (ILR): The dielectric loss ratio reflects the degree of deterioration of the insulating oil. For new insulating oil, the ILR should be within the normal range (usually measured at 25°C, the normal value of ILR should be between 1.0 and 3.0); if it is out of range, it may need to be replaced.
Partial discharge detection
Partial discharge signal strength: The discharge signal in the transmission insulation can be detected by the partial discharge monitoring equipment. Under normal circumstances, the discharge signal strength should be lower than the set value.
Environmental factors
Check whether the transmission insulation material is affected by environmental factors such as temperature, humidity and pollutants. These factors may accelerate the aging of the insulation material or cause performance degradation.
Generally, high humidity and pollutant environment are the main reasons affecting the life of the insulation material. The service life of the insulation material can be extended by installing a dehumidification device or taking appropriate protective measures.
Equipment operation status
In the power system, the inspection of transmission insulation should also be carried out in combination with the actual operation status of the equipment. For example, if the equipment is in a state of frequent start-stop, it may affect the insulation performance of the insulation material.
By analyzing the operating parameters of the equipment (such as current, voltage, etc.), the health status of the transmission insulation can be indirectly evaluated.
Conditional evaluation of transmission insulation
Selection of insulation materials
When selecting transmission insulation materials, comprehensive consideration should be given to the specific application scenarios and working conditions. For example, a high humidity environment may be more suitable for the use of moisture-resistant insulation materials.
The selection of insulating oil should be selected according to the standards to ensure the long-term stable operation of the product
Performance parameters of insulation materials
Attention should be paid to the key performance parameters of transmission insulation materials, including insulation resistance value, dielectric loss ratio (ILR), partial discharge intensity, etc. These parameters should meet the requirements of relevant technical specifications.
For insulating oil, factors such as its freezing point and viscosity will also affect its actual application effect.
Maintenance strategy of equipment
Develop a reasonable maintenance strategy based on the actual situation of transmission insulation. For example, for insulation materials that are susceptible to environmental influences, regular dehumidification and anti-fouling treatment can be taken.
Regular preventive inspections and evaluations can help to detect potential problems in a timely manner and take corresponding measures.
Abnormal situation handling
If transmission insulation is found to be seriously aged or degraded, it should be replaced immediately. Avoid minor problems that lead to major failures.
When handling abnormal situations, standardized operating procedures should be followed to ensure the quality of repairs and extend the service life of the equipment.
Common transmission insulation failures
Insulator corrosion
As the insulation material is exposed to various pollution, weathering and corona activities that produce nitric acid, the galvanized finish on fittings and pins will gradually be lost.
Chalking
Chalking on insulators is usually not a pressing issue, but rather indicates that the insulation layer is beginning to age, leading to consideration of long-term retirement. This phenomenon is usually caused by UV degradation over time. Chalking does not usually occur in silicone polymer insulators, but can be prevalent on EPR/EPDM housings, making these materials less suitable for transmission applications. While chalking may not cause an immediate problem, it does allow contaminants to accumulate more quickly and promotes an increased incidence of water film formation on the insulator surface, a loss of hydrophobicity.
Delamination or leakage of insulating oil layer
It may be caused by improper storage conditions or excessive load of equipment during long-term operation.
Pollution and damage from birds and other sources
Such pollution reduces the ability of the insulator to achieve its full electrical insulation performance. Random flashovers may then occur, usually in wet conditions in the early morning or with light rain. While most insulating materials may be contaminated to some extent, for silicone rubber materials, the insulator remains resilient under mild to moderate pollution.
Summary and Suggestions
Transmission insulation is an integral part of the power system, and its health status directly affects the safety and service life of the equipment. Therefore, regular actual inspection and condition assessment of transmission insulation is very important. The inspection methods and technical specifications introduced in this article provide a reference for power system maintenance personnel.
In actual work, a scientific and reasonable maintenance strategy should be formulated in combination with the specific operating conditions and environmental factors of the equipment, and the relevant technical specifications should be strictly followed. At the same time, paying close attention to changes in the operating parameters of the equipment, timely discovering and dealing with potential problems, can effectively extend the service life of transmission insulation materials.
In short, through regular inspections and condition assessments, it can be ensured that the transmission insulation materials are always in the best condition, thereby providing strong guarantees for the safe operation of the power system.
