Ⅰ. Introduction
As essential power conversion devices for medium-voltage power grids, 33kv transformer units are widely adopted in industrial and municipal power distribution scenarios. Designed for outdoor long-term operation, oil filled distribution transformers stand out for their excellent heat dissipation and insulation performance. This article takes this mature power distribution device as the core topic to comprehensively introduce its complete internal structure, working mechanism and standard maintenance guidelines.
Professional power transmission and distribution equipment manufacturer JINSHANMEN TECHNOLOGY CO., LTD focuses on the R&D, production and customization of various transformers and complete power distribution equipment. 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. All products comply with international industry standards and are widely exported to overseas markets.
Ⅱ. High-Voltage & Low-Voltage Side Components
The voltage conversion of medium-voltage power grids relies on the cooperative work of high-voltage and low-voltage components. These core structures serve as the power inlet and outlet channels, realizing safe and stable voltage conversion for power grid operation.
1. High-Voltage Side Components
The high-voltage inlet terminal connects 33kV high-voltage transmission lines through busbars or cables to receive grid electric energy. The high-voltage bushing is a key insulating part for winding leads penetrating the fuel tank. Made of porcelain or epoxy resin materials, it effectively prevents high-voltage discharge toward the tank body. The outer umbrella skirt structure increases creepage distance, avoids flashover faults caused by dust and humidity, and guarantees the stable operation of power distribution equipment in harsh outdoor environments.
2. Low-Voltage Side Components
The low-voltage outlet terminal outputs stepped-down electric energy (usually 400V) to supply power for industrial equipment and civilian electrical loads. The low-voltage bushing adopts a structural design similar to the high-voltage bushing, with lower insulation grade and smaller overall size, which perfectly matches the low-voltage output demand of conventional distribution transformers.
Ⅲ. Oil System Core Components
The insulating oil system is the core support for transformer insulation and heat dissipation, directly determining the service life and operational stability of oil filled distribution transformers. The complete oil system includes an oil conservator, breather, fuel tank, oil level gauge and oil drain valve, covering all links of oil storage, ventilation, detection and maintenance.
1. Oil Conservator (Oil Tank)
Installed on the top of the fuel tank, the oil conservator is specially used for storing insulating oil. It can effectively compensate the volume change of insulating oil caused by thermal expansion and cold contraction under different temperature conditions. Meanwhile, it isolates most of the oil from air contact, slows down oil oxidation and aging, and greatly extends the service cycle of the transformer. A matched oil level gauge is installed on the side for real-time oil level observation.
2. Breather (Dehumidifier)
The breather is installed on the ventilation pipeline of the oil conservator and filled with high-efficiency silica gel desiccant. It can absorb moisture and impurities in the air entering the oil system to prevent insulating oil from getting damp and deteriorating. When the blue silica gel turns pink after absorbing moisture to saturation, it needs to be replaced or dried in time to ensure the dry and clean state of the internal oil system of 33kv transformer equipment.
3. Fuel Tank & Auxiliary Parts
The fuel tank adopts an integral welded steel structure, which is the main carrier for placing internal iron cores, windings and insulating oil. The fully filled insulating oil in the tank provides dual protection of electrical insulation and operational heat dissipation. The oil drain valve at the bottom is convenient for oil discharge during equipment maintenance and oil sample extraction for withstand voltage testing. The oil level gauge is marked with standard scales from -20℃ to +40℃ to guide standardized oil level management.
Ⅳ. Heat Dissipation System
The heat dissipation system determines the continuous load operation capacity of the transformer, mainly composed of radiators and automatic cooling fans. Sheet or tubular radiators accelerate the heat exchange between insulating oil and ambient air. The more the radiator groups, the stronger the heat dissipation efficiency. High-performance equipment represented by 33kv transformer is equipped with intelligent cooling fans to cope with high-load operation.
The cooling fan will automatically start when the oil temperature or operating load reaches the preset threshold. The forced air cooling mode speeds up heat dissipation, effectively improves the transformer's power output capacity, supports short-term overload operation, and ensures stable power supply during peak electricity consumption periods.
Ⅴ. Safety Protection Components
To prevent equipment damage and safety hazards caused by internal short circuits, overheating and other faults, reliable power distribution transformers are equipped with complete safety protection structures, including rising seats, pressure relief devices and main transformer terminal boxes.
1. Rising Seat
Installed under the high and low voltage bushings, the rising seat is the fixed installation cavity for current transformers (CT). The built-in through-type CT can realize real-time current measurement, differential protection and overcurrent protection, realizing real-time monitoring and early fault warning of transformer operating parameters.
2. Pressure Relief Device
When serious faults such as internal short circuit occur inside the transformer, a large amount of high-pressure gas will be generated instantly. The pressure relief device can automatically open for pressure relief to avoid tank explosion accidents caused by excessive internal pressure. After the action, manual fault inspection, reset or sealing replacement is required to restore the protection function.
3. Main Transformer Terminal Box
The main transformer terminal box is the external signal transmission hub of the equipment, internally equipped with terminal rows, relays, temperature controllers and other components. It can collect key data such as oil temperature, winding temperature and oil level, and connect with the background protection and measurement control system to realize intelligent monitoring and automatic safety protection.
Ⅵ. Daily Maintenance Key Points
Standardized daily maintenance is the key to prolonging the service life of power distribution transformers and reducing failure rates. Scientific operation and maintenance can ensure long-term stable operation of medium-voltage power distribution systems.
1. Regularly check the oil level, supplement oil when the oil level is too low, and drain excess oil when the oil level is too high to keep the oil level within the standard scale range. 2. Observe the color of the breather silica gel, replace or dry it in time when it turns pink due to moisture absorption. 3. Inspect radiators for oil leakage and check the operating sound and speed of cooling fans to ensure normal heat dissipation. 4. Regularly conduct oil sample chromatographic analysis to judge potential internal discharge and overheating faults. 5. Once the pressure relief device acts, check the fault cause thoroughly before resetting and putting it into operation.
Ⅶ. Summary
Each component of oil filled distribution transformers has independent functional attributes and coordinated operation logic, covering power transmission, insulation, heat dissipation and safety protection. As a professional power equipment manufacturer, JINSHANMEN TECHNOLOGY CO., LTD provides full-series, high-quality transformer and substation equipment, supporting customized solutions for various overseas power distribution projects.