Analysis of independent oil system of oil immersed transformer
Writer： Hengfeng you electric Time：2023-04-12 views：times
Oil immersed transformers have several isolated oil systems. During the operation of oil immersed transformer, the oil in these independent oil systems is not connected with each other, and the oil quality and operating conditions are also different. Chromatographic analysis of gas in oil should be done separately to identify potential problems.
(1) Oil system in the main body. The oil system connected with the oil around the winding is the system in the main body, including the oil in the cooler or radiator, the oil in the oil conservator and the oil in the oil filled bushing of 35kV and below.
During oil filling, the gas vent plug stored in the oil system must be discharged. Generally speaking, the above components shall have their own vent plug. The oil in the main body mainly has the effect of insulation and cooling. Oil can also be added with insulating paper or
Electrical strength of insulating paperboard. During vacuum oil filling, if some parts cannot accept the same vacuum strength as the main oil tank, temporary gate shall be used for blocking, such as the gate valve between the oil conservator and the main oil tank. The lift of the submersible pump on the cooler shall be sufficient to prevent air from being sucked in due to negative pressure. The oil system should have a maintenance system of pressure relief equipment to eliminate the pressure when there is something wrong with the device.
(2) Oil in on load tap changer switching switch room. This part of oil has its own maintenance system, namely flow relay, oil conservator and pressure release valve. The oil in this switch room has the effect of insulation and extinguishing current. The oil will be removed from the oil generated when the switching switch blocks the load current. The oil system should have excellent sealing function, and the sealing function should be maintained even if the arc pressure occurs during the switching process.
Although the oil in the on load tap changer switching switch room is blocked from the oil in the main body, during vacuum oil injection, in order to prevent damaging the seal of the switching switch room, vacuum oil injection shall be carried out simultaneously with the oil in the main body. During vacuum oil injection, the two systems shall have the same vacuum degree. If necessary, the oil conservator of this system shall also be blocked during vacuum pumping. In order to facilitate the structure, the oil conservator of the main body and the oil conservator of the change-over switch room are planned as a mutually isolated whole.
(3) Fully sealed with voltage level of 60kV and above. The main insulation effect in this oil system, or add oil to the electrical strength of insulating paper in capacitive bushing. When filling oil in the main body, the terminal at the end of the sleeve shall be sealed to prevent air intake.
(4) Oil in high-voltage outlet box or oil in gas outlet box. The high-voltage outgoing line of three-phase 500kV transformer passes through corrugated insulation barrier oil system. This oil system has the primary effect of insulation.
In order to simplify the structure, the oil system can also be connected with the oil system in the main body through connecting pipes or planned into a separate oil system.
(5) When conducting various insulation experiments on oil immersed transformers, the first step is to release the gas that may be stored through the vent plug. By analyzing the gas content in the oil of each system, chromatographic analysis can predict whether there are potential problems. Each oil system shall meet the requirements of operation, such as the change of oil volume when absorbing oil expansion and contraction, oil drain valve, vent plug, barrier valve between cooler and radiator and main oil tank, etc. Each oil system has excellent sealing function. The oil in the on load tap changer change-over switch room can be replaced independently without discharging the oil in the main body. During transportation, the oil in the main body can be discharged and filled with dry nitrogen.
For more information about transformers, please contact us. Email: hfy@hengfengyou.com , we will give you more detailed answers and look forward to your consultation!
