Three Phase Oil Immersed Transformer Structure

1- nameplate; 2- signal thermometer; 3- moisture absorber; 4- oil level; 5- oil storage tank; 6- safety airway; 7- gas relay; 8- high voltage bushing; 9- low voltage bushing; 10- tap changer; 11- oil tank; 12- oil drain valve; 13- body; 14- grounding plate; 15- trolley; 16 pressure relief valve

(1) Nameplate: specifically stated in the technical parameters;

(2) Signal thermometer: thermal protection device, monitor the temperature of oil and winding, the life of the three phase oil immersed transformer depends on its operating temperature

(3) Dehumidifier: The dehumidifier is also known as the respirator, and the commonly used dehumidifier is a hanging dehumidifier structure. The moisture absorber is equipped with adsorbent silica gel, and the insulating oil in the oil pillow communicates with the atmosphere through the moisture absorber, and the internal adsorbent absorbs moisture and impurities in the air to maintain the good performance of the insulating oil. In order to show the moisture of the silica gel, color-changing silica gel is generally used. The principle of color-changing silica gel is that it is made of several different colors based on the amount of crystal water contained in cobalt dichloride (CoCL2). When cobalt dichloride contains six molecules of crystal water, it is pink; when it contains two molecules of crystal water It is purplish red; it is blue when it does not contain crystal water. The function of the respirator is to provide a passage for the internal gas of the transformer to enter and exit when the temperature changes, and to relieve the pressure on the oil tank due to temperature changes during normal operation. The role of the silica gel in the respirator is to dehumidify the inhaled gas when the temperature of the three phase oil immersed transformer drops. The role of the oil seal cup is to prolong the service life of the silica gel and isolate the silica gel from the atmosphere. Only the air entering the transformer passes through the silica gel.

(4) Oil standard: you can observe the height of the oil level, the oil level should be half as high

(5) Oil conservator: When the volume of transformer oil expands or decreases with the temperature of the oil, the oil conservator plays the role of regulating the oil volume and ensuring that the transformer oil tank is always filled with oil. If there is no oil conservator, the fluctuation of the oil level in the fuel tank will bring some unfavorable factors: first, when the oil level lowers, the exposed core and coil will affect the heat dissipation and insulation; Discharge and suction, and because the upper oil temperature is very high, the oil will be quickly oxidized and damp. The oil surface of the oil conservator is smaller than the oil surface of the fuel tank, so that the contact surface between oil and air can be reduced to prevent the oil from being oxidized and dampened too quickly. The third is that the oil in the oil conservator hardly participates in the circulation in the fuel tank at ordinary times. Its temperature is much lower than that of the upper oil in the fuel tank, and the oxidation process of the oil is also much slower. Therefore, the oil conservator can prevent the oil from oxidizing. Oxidation too fast.

(6) Safety airway: The explosion-proof tube, also known as the safety airway, is installed on the upper cover of the fuel tank, and is communicated with the atmosphere by a trumpet-shaped tube, and the nozzle is sealed with a film glass plate or phenolic cardboard. In order to prevent the explosion-proof membrane from loosening or being damaged due to the rise of the oil level in the explosion-proof pipe and the air pressure in the pipe under normal circumstances, and the gas relay malfunctioning, a small pipe is connected between the explosion-proof pipe and the oil conservator to equalize the pressure at both places. The function of the explosion-proof tube is to discharge the gas decomposed in the oil in time when a fault occurs inside the transformer, so as to prevent the explosion or deformation of the oil tank caused by a sudden increase in the internal pressure of the transformer. Oil-immersed transformers with a capacity of more than 800KVA are equipped with explosion-proof tubes, and the burst pressure of the protective film should be lower than 50662.5Pa

(7) Gas relay: When the transformer fails, the body of the three phase oil immersed transformer will overheat, causing the oil to decompose and generate gas. If a small amount of gas is generated, an alarm signal will be issued, and if a large amount of gas is generated, the trip circuit will be connected to cut off the power supply.

(8) High-voltage bushing: The insulating bushing is the main insulating device outside the three phase oil immersed transformer box. The lead-out wire of the transformer winding must pass through the insulating bushing to insulate the lead-out wires and the transformer shell. At the same time, it plays the role of fixing the lead-out line.

(9) Low-voltage bushing: The insulating bushing is the main insulation device outside the three phase oil immersed transformer box. The lead-out wire of the transformer winding must pass through the insulating bushing to insulate the lead-out wires and the transformer shell. At the same time, it plays the role of fixing the lead-out line.

(10) Tap changer: The output voltage of the transformer may change due to changes in the load and primary side voltage. The tap changer can be used to control the output voltage within the allowable range. The tap changer is generally installed on the primary side (high voltage side). The output voltage is adjusted by changing the primary side; transformer voltage regulation is to set a tap on a certain winding of the transformer, and when the tap is changed, a part of the turns is reduced or increased, so that the number of turns of the transformer winding with the tap is reduced or Increase, the number of turns of other windings does not change, thus changing the turns ratio of the transformer winding. When the turns ratio of the winding changes, the voltage ratio also changes accordingly, and the output voltage changes, thus achieving the purpose of adjusting the voltage. In general, appropriate taps are extracted from the high-voltage windings, because the high-voltage windings are often set outside, and it is convenient to lead out the taps; in addition, the current on the high-voltage side is small, and the cross-sectional area of the tap leads and the current-carrying part of the tap changer is small. The switch contact part is also easy to solve. There are two ways of voltage regulation: non-excitation voltage regulation and on-load voltage regulation. In off-excitation voltage regulation, the transformer is not secondary without load, but all sides of the transformer are disconnected from the grid, and the winding taps are changed when the transformer is off-excitation; in on-load voltage regulation, the transformer does not interrupt the load. In the case of changing the tap of the winding.

(11) Oil tank: The oil tank is filled with transformer oil, which first protects the iron core and windings from moisture, and also plays the role of insulation and heat dissipation.

(12) Oil drain valve: As the name implies, it is a valve used to drain transformer oil.

(13) Body: iron core and winding. Iron core: The iron core is one of the important components in the power transformer. It is made of high-permeability silicon steel sheets laminated and clamped by steel clamps. The iron core has two functions. In principle, the core is the magnetic circuit that constitutes the transformer. It converts the electrical energy of the primary circuit into magnetic energy, and then converts the magnetic energy into the electrical energy of the secondary circuit. Therefore, the iron core is the medium of energy transmission. Structurally, it is the skeleton that constitutes the transformer. Put insulated coils on its iron core, and firmly support and compress them; Winding: Winding is the most basic part of the transformer. part of the circuit. It is made of copper or aluminum insulated wire wound. The primary winding inputs electrical energy, and the secondary winding outputs electrical energy. The higher voltage of the two windings is called the high voltage winding, and the lower voltage is called the low voltage winding. Power transformers with different capacities and voltage levels have different winding forms. Generally, power transformers often adopt two structural forms: concentric type and overlapping type.

(14) Grounding plate: used as the grounding of the three phase oil immersed transformer shell.

(15) trolley: easy to carry

(16) Pressure release valve: When a fault occurs inside the transformer, gas is generated, and the internal pressure exceeds 50KPa. The oil and gas will push against the diaphragm disc to release the pressure and play a protective role.