Brief introduction of transformer conservator
The conservator is an oil storage device used in the transformer. Its function is to expand the oil in the oil tank when the oil temperature rises due to the increase of the load of the transformer. At this time, too much oil will flow into the conservator. On the contrary, when the temperature decreases, the oil in the conservator will flow into the oil tank again to automatically adjust the oil level, that is, the conservator plays the role of oil storage and oil replenishment, which can ensure that the oil tank is full of oil. At the same time, since the oil conservator is equipped, the contact surface between the transformer and the air is reduced, and the moisture, dust and oxidized oil dirt absorbed from the air are deposited in the precipitator at the bottom of the oil conservator, thus greatly slowing down the deterioration speed of the transformer oil.
Structure of oil conservator: the main body of the oil conservator is a cylindrical container welded with steel plates, and its volume is about 10% of the volume of the oil tank. The conservator is horizontally installed on the top of the oil tank. The oil inside is connected with the transformer oil tank through the connecting pipe of the gas relay, so that the oil level can rise and fall freely with the change of temperature. Under normal conditions, the lowest oil level in the oil conservator shall be higher than the raised seat of the high-pressure casing. For the casing with connected structure, the lowest oil level in the oil conservator shall be higher than the top of the casing. A glass oil level gauge (or oil level gauge) is installed on the side of the oil conservator to observe the change of the oil level in the conservator at any time.
Form of transformer conservator
There are three types of transformer conservator: corrugated type, capsule type and diaphragm type.
1. The capsule type oil conservator separates the transformer oil from the external atmosphere with rubber capsules inside, and provides the transformer oil with space for thermal expansion and cold contraction.
2. Diaphragm type conservator is used to separate the transformer oil from the external atmosphere with rubber diaphragm and provide space for thermal expansion and cold contraction of the transformer oil.
3. Corrugated oil conservator is a metal expander composed of metal corrugated sheets to separate transformer oil from the external atmosphere and provide space for thermal expansion and cold contraction of transformer oil. The corrugated oil conservator is divided into internal oil conservator and external oil conservator. The internal oil conservator has better performance but larger volume.
Sealing of transformer conservator
The first type is an open (unsealed) oil conservator, in which the transformer oil is directly connected with the outside air. The second type is a capsule oil conservator, which has been gradually reduced in use because the capsule is easy to age and crack and has poor sealing performance. The third type is diaphragm type oil conservator, which is made of two layers of nylon cloth with a thickness of 0.26rallr-0.35raln, with neoprene sandwiched in the middle and cyanogen butadiene coated on the outside. However, it has higher requirements for installation quality and maintenance process, and its use effect is not ideal, mainly due to oil leakage and wearing rubber parts, which affect the safety, reliability and civilized production of power supply. Therefore, it is also being gradually reduced. The fourth type is the oil conservator using metal elastic elements as compensators, which can be divided into two categories: external oil type and internal oil type. The inner oil vertical oil conservator uses corrugated pipes as the oil container. According to the amount of compensated oil, one or more corrugated pipes are used to place the oil pipes on a chassis in parallel and in a vertical manner. The dust cover is added externally. The volume of insulating oil is compensated by moving the corrugated pipes up and down. The appearance is mostly rectangular. The external oil horizontal oil conservator is placed horizontally in the cylinder of the oil conservator with the bellows as the air bag. The insulating oil is contained between the outer side of the bellows and the cylinder, and the air in the bellows is communicated with the outside. The internal volume of the oil conservator is changed by the expansion and contraction of the bellows to realize the volume compensation of the insulating oil. The external shape is a horizontal cylinder:
1 open type oil conservator (conservator) or low-voltage small capacity transformer iron barrel oil tank is the most original, that is, the oil tank connected with the outside air is used as the oil conservator. Because of its unsealed, the insulating oil is easy to be oxidized and affected by moisture. After long-term operation, the quality of the transformer oil is oxygenated, and the micro water and air content of the deteriorated transformer oil seriously exceed the standard, which poses a great threat to the safe, economic and reliable operation of the transformer, Which seriously reduces the safety of the transformer and the service life of the insulating oil. At present, this kind of oil conservator (conservator) is basically eliminated, which is rarely seen in the market, or is only used on transformers with lower voltage levels:
2 capsule type oil conservator capsule type oil conservator is an oil resistant nylon capsule bag installed inside the traditional oil conservator. It isolates the transformer oil in the transformer body from the air: as the oil temperature in the transformer rises and falls, it breathes, When the volume of oil changes, there is a sufficient space: its working principle is that the gas in the capsule bag is communicated with the atmosphere through the breathing tube and the moisture absorber. The bottom of the capsule bag is close to the oil level of the oil conservator. When the oil level changes, the capsule bag will also expand or compress: because the rubber bag may crack due to material problems, air and water will infiltrate into the oil and enter the transformer oil tank, resulting in increased water content in the oil, The insulation performance decreases and the oil dielectric loss increases, which accelerates the aging process of the insulation oil: therefore, the silicone rubber particles of the transformer need to be replaced. When the cleaning condition is serious, the transformer needs to be forced to filter the oil or cut off the power for maintenance.
3 isolated oil conservator diaphragm oil conservator solves some problems of capsule type, but the quality problem of rubber material is difficult to solve, so that quality problems may occur in operation, which poses a threat to the safe operation of power transformers. 4 the technology adopted by metal corrugated (inner oil) sealed oil conservator is mature, The extension and amplification of the elastic element - sheet metal expander technology for transformer, which has been widely used in the power system for more than 20 years, is also to fill an elastic element with transformer oil and let its core expand and contract up and down to compensate the oil amount. The internal oil conservator is a two corrugated core (1 cr18nigti) composed of vacuum exhaust pipe, oil injection pipe, oil level indicator, flexible connecting pipe and cabinet foot. It is made of stainless steel with atmospheric corrosion resistance and high temperature resistance, which can meet the life of more than 20000 round trips. The core moves up and down with the change of transformer oil temperature and automatically compensates with the change of transformer oil volume.
(1) a pressure protection device damper is installed in the inner cavity of the core, which can delay the impact on the oil storage cabinet caused by the sudden increase of oil pressure in the transformer. When the core limit is reached, the core will break, and the transformer body will be protected by pressure relief, thus increasing the reliability of transformer operation. This function is not available in other conservators.
(2) the core is composed of one or more cores, with a protective cover outside. The outside of the core is connected to the atmosphere, which has good heat dissipation and ventilation effect, can accelerate the circulation of transformer oil, reduce the oil temperature in the transformer, and improve the reliability of transformer operation
(3) the oil level indication is also the same as the sheet metal expander for transformer. With the expansion and contraction of the core, the indicator board also rises or falls with the core. The sensitivity is high, and the oil level change can be seen through the observation window installed on the outer protective cover, which is intuitive and reliable. The alarm device and a range switch for monitoring the oil level are installed on the outer protective volume, which can meet the needs of unattended operation
(4) there is no false oil level phenomenon: various types of oil conservators in operation can not exhaust the air completely, which may cause false oil level. Secondly, the technology has high sensitivity due to the fact that the core is telescoping up and down. In addition, there is a balance steel plate in the core, which generates micro positive pressure, so that the air in the core can be smoothly exhausted until the air is completely exhausted and reaches the required oil level, thus eliminating the false oil level.
(5) the on load tap changer oil tank should not use the metal corrugated expander on load tap changer as an important component of the transformer. During its operation, it needs to adjust the voltage regularly according to the load condition. Secondly, because the arc will inevitably be generated during the adjustment process and certain gas will be generated, which is restricted by the volume of the fully sealed metal corrugated expander, which is not conducive to the release of gas generated by oil decomposition, It is necessary to send people to the site to exhaust frequently. Neither the manufacturer nor the user advocate that the small oil conservator with on-load tap changer should adopt the fully sealed metal corrugated expander:
Post time: Nov-13-2024