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What is the distribution transformer?


Distribution transformer,  refers to the distribution system in accordance with the law of electromagnetic induction to transform AC voltage and current and transmission of AC electricity static electrical appliances. Some areas will be below 35 kv (most of them are 10KV and below) voltage level of power transformers, called "distribution transformer". The place where the distribution transformer is installed is both a substation. Distribution transformers should be installed on a column or on the ground in the open air.

According to its structure, oil-immersed distribution transformer can be divided into body, oil storage tank, insulation bushing, tap switch, protection device, etc.

Distribution transformer structure decomposition

  1. The body consists of the core, winding and insulating oil. The winding is the circuit of the transformer, and the core is the magnetic circuit of the transformer. The two constitute the core of the transformer electromagnetic part.

  2. Iron Core The iron core is the main magnetic circuit part in the transformer. It is usually made of stacked hot-rolled or cold-rolled silicon steel sheets with a high silicon content, a thickness of 0.35 or 0.5mm, and coated with insulating paint on the surface. The iron core is divided into two parts: the iron core column and the iron yoke. The iron core column is covered with windings and the iron yoke is used to close the magnetic circuit. There are two basic forms of core structure: core type and shell type.

  3. Winding The winding is the circuit part of the transformer, generally made of insulated flat copper wire or round copper wire wound on the winding die. The windings are set on the core column of the transformer, the low-voltage windings are set on the inner layer, the high-voltage windings are set on the outer layer of the low-voltage windings, between the low-voltage windings and the iron core, between the high-voltage windings and the low-voltage windings, are separated by insulating materials made of sleeve, so as to facilitate insulation.

  4. insulation oil, The composition of insulating oil transformer oil is very complex, mainly composed of cycloalkanes, alkanes and aromatic hydrocarbons, transformer oil in the distribution transformer plays two roles: one is in the transformer windings and windings, windings and core and oil tank between the insulating effect.

  5. Insulation bushing is the main insulation device outside the transformer box. Most of the transformer insulation bushing uses porcelain insulation bushing. The transformer leads the high and low voltage windings of the transformer from the tank to the outside of the tank through the high and low voltage insulating bushings, so that the transformer windings are insulated to the ground (shell and core), and it is the main part of the fixed lead and the external circuit connection. The high pressure porcelain bushing is taller, while the low pressure porcelain bushing is shorter.

  6. Tap transformer high voltage windings change tap device, adjust tap position, can increase or decrease the number of turns in the primary winding part, to change the voltage ratio, so that the output voltage is adjusted. After the transformer is out of operation and disconnected from the grid, the position of the tap switch is manually changed, and the output voltage is adjusted, which is called no-load voltage regulation.

  7. Gas relay Gas relay is installed in the middle of transformer oil tank and oil storage tank connection pipe, connected with the control circuit to form a gas protection device.

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