The important structure of oil-immersed transformer

1. Iron core

Iron core is the oil-immersed transformer in the most important part of the equivalent circuit. Generally by the silicon content is relatively high, the thickness of 0.35 or 0.5 mm, the surface layer coated with three anti-painting hot rolled steel or cold rolled steel ferrite core stacked into the core is divided into the core column and the yoke of two parts of the core column set with the winding resistance, the yoke off the equivalent of the circuit of the use of the yoke. The basic form of the core structure with the core or shell two forms.

2. Winding resistance

Winding resistance is part of the line of oil-immersed transformer, generally with insulating layer of flat copper wire or round copper wire in the winding mold winding production and become. Winding resistance suits in the oil-immersed transformer core column, low-voltage winding in the layer, high-voltage winding suits in the low-voltage winding surface layer, low-voltage winding and core middle, high-voltage winding and low-voltage winding in the middle, will be made with the insulation layer material separated from the nut, so as to facilitate the insulation layer.

3.Transformer oil

Oil-immersed transformer oil composition is very complex, generally consists of cyclic hydrocarbons, ethane and aliphatic hydrocarbons, oil-immersed transformer oil in the distribution equipment in the oil-immersed transformer oil plays two key points: one is in the oil-immersed transformer winding resistance and windings, windings and cores and the oil tank in the middle of the insulating layer effect. Second, the oil-immersed transformer oil is heated to cause thermal convection, the oil-immersed transformer core and winding resistance to play a heat conduction effect. Common oil-immersed transformer oil has 10, 25 or 45 three sizes, its model indicates that the oil gradually condenses at sub-zero temperature, such as “25” oil reveals that this type of oil in sub-zero 25 ℃ when the beginning of condensation. Oil sizes should be selected according to local natural conditions.

4. Oil reservoir

The oil conservator is mounted on the cover of the oil tank. The volume of the oil conservator is 10% or less of the weight of the oil tank. There is a pipe connection between the oil conservator and the oil tank. When the volume of oil-immersed transformer along with the liquid temperature changes and surge or shrinkage, the oil conservator plays the role of oil storage tank and oil replenishment, to protect the core and winding resistance soaked in oil; and due to the installation of the oil conservator, reduce the contact area of oil and air, reduce the rate of oil deterioration.

Oil level meter on the side of the oil conservator, in the vicinity of the glass test tube has a temperature in -30 ℃, +20 ℃ and +40 ℃ when the oil level of the relative height of the baseline, indicating that the oil-immersed transformer not put into use should be reached the oil level of the relative height of the baseline key to reflect the oil-immersed transformer in various conditions of operation, the remaining oil is sufficient.

Oil storage cabinet with breathing holes, so that the upper end of the oil storage cabinet indoor space and atmospheric interoperability. Oil-immersed transformer oil heat up and cold shrinkage, oil storage cabinet upper gas can breathe through the hole in and out of the oil level can rise or fall, to avoid the oil tank shape or even damage.

5. Insulation tube

This is an oil-immersed transformer box on the important insulation layer equipment, the vast majority of oil-immersed transformer insulating pipe selection of porcelain insulating pipe. Oil-immersed transformer through the high and low voltage insulation tube, the oil-immersed transformer high and low voltage winding wire from the oil tank to the oil tank outside the oil tank, so that the oil-immersed transformer winding resistance to the ground voltage (shell and core) insulation layer, but also a fixed immobile conductor and the main components of the external circuit connection. High-voltage porcelain casing is taller and larger, low-voltage porcelain casing is shorter.

6. Tap tap

Oil-immersed transformer high-voltage winding to change the tapping device, adjust the tap part, can increase or reduce the primary winding part of the coil turns, in order to change the voltage ratio, so that the voltage is regulated. Oil-immersed transformer in the withdrawal of operation, and disconnected from the power grid and then manually change the tap changer area of the method, and adjust the voltage is called no-load voltage regulation.

7. Gas relay

The gas relay is connected to the oil tank of the oil-immersed transformer and the oil conservator in the middle of the rubber tube, and the control circuit is connected to form the gas protection equipment. The upper contact of the gas relay and the light gas signal constitute an independent control circuit, and the lower connector of the gas relay is connected to the external circuit to form the heavy gas protection, and the heavy gas posture makes the high voltage universal circuit breaker and sends out the heavy gas action signal.

8. Explosion-proof pipe

Explosion-proof tube is a kind of safety protection device of oil-immersed transformer, connecting to the upper side of the big cover of oil-immersed transformer, the explosion-proof tube is intercommunicated with the atmosphere, and the heat generated from the fault will make the oil of oil-immersed transformer gasify, and the gas relay will be activated to send out an alarm signal or shut down the power supply to prevent the oil tank from cracking.