1. Transformer Stabilization The transformer can be directly placed into the transformer room by using the car crane, or the temporary track can be set up with the road wood. It can be hoisted to the temporary track with a three-step hoist and chain, and then pulled into the indoor suitable position with the hoist chain. When the transformer is in place, it should be noted that its orientation and distance from the wall are consistent with the drawing. The allowable error is ±25mm. When the drawing is not marked, the longitudinal direction is in place, the lateral distance wall shall not be less than 800mm, and the distance door shall not be less than 1000mm.

Installation of the transformer frame: The transformer is installed on the double pole, and the root of the two poles is 2m. The distribution transformer gantry is fixed on two poles by two or four channel steels. The height of the gantry is not less than 25m from the ground, and the plane slope of the gantry is not more than 1/100. The waist bar should be wrapped with iron wire with a diameter of not less than 4mm for more than two turns, and the winding should be tight, and the waist portion should be no less than 0.2m from the live part. At the same time, the transformer high-pressure column head is equipped with a dust cover and the transformer is suspended with a warning sign.

2. Installation of drop fuses The fuses should be installed on the high and low voltage sides of the transformer. The vertical height of the bottom of the high-voltage side fuse to the ground is not less than 4.5m, and the horizontal distance of each phase fuse should not be less than 0.5m. In order to facilitate the operation and the fuse can be smoothly dropped after the fuse is blown, the drop-type fuse is blown down. The axis of the device should be at an angle of 15 to 30 degrees from the vertical. The vertical distance of the bottom of the low-voltage side fuse to the ground is not less than 3.5m, and the horizontal distance of each phase fuse is not less than 0.2m.

The selection of the fuse of the drop fuse is selected according to the principle of “guaranteeing the internal fuse or the high-voltage and low-voltage outlet bushings when the short-circuit is short-circuited”. The fuse blow time must be less than or equal to 0.1s. According to the regulations: for the capacity of 100kVA or less, the rated current of the high-voltage fuse is selected according to the rated current of the transformer capacity of 2~3 times; for the capacity of 100kVA or above, the rated current of the high-voltage fuse is 1.5~2 of the rated current of the transformer capacity. Double selection. The low-voltage side fuse of the transformer frame is selected according to the rated current of the low-voltage side.

3. Installation of arrester The operating experience proves that most of the external dangers affecting the safe operation of the distribution transformer are from lightning accidents. Therefore, the transformer should be equipped with lightning protection devices. Our bureau chooses the gapless synthetic insulation jacket metal oxide arrester to replace the original valve type porcelain jacket lightning arrester, which has strong power frequency voltage tolerance, good sealing performance and stable protection characteristics. The arrester should be installed between the fuse and the transformer as close as possible to the transformer.

This not only effectively protects the transformer, but also facilitates maintenance. In addition, in order to prevent intrusion of the reverse-converted wave and the low-voltage side lightning wave, a low-voltage arrester should be installed on the low-voltage side. In order to avoid the voltage drop of the lightning current on the grounding resistance and the residual voltage of the arrester, it acts on the transformer insulation. The grounding end of the arrester, the outer casing of the transformer frame and the neutral point of the low-voltage side should be no less than 25mm2. The copper core plastic wires are connected together and connected to the grounding device.

4. Grounding device In the current rural power network transformation, there are many small-capacity transformers in rural areas. The 10kV distribution transformers in the thunderstorm season often suffer lightning strikes. Because the grounding resistance is too large, the specified values are not met, and the lightning current cannot be quickly discharged into the earth, causing the lightning arrester. The residual voltage is too large, or a high voltage drop occurs on the grounding resistance, causing the transformer to burn. Therefore, the grounding resistance of the grounding device must comply with the regulations. For 10kV distribution transformers: the grounding resistance should be no more than 10Ω below 100kVA; the grounding resistance should be no more than 4Ω above 100kVA. After the grounding device is finished, the grounding resistance test should be carried out. After passing the test, the earth can be backfilled.

At the same time, the transformer frame shell must be well grounded, the shell grounding should be tightened with bolts, and it should not be welded directly for welding. The underground part of the grounding device is composed of a horizontal grounding body and a vertical grounding body. The horizontal grounding body adopts a 40×4mm flat steel with a length of 6m, and the vertical grounding body adopts three L50×50×5mm angle steels with a length of 2m. Solder separately with the horizontal grounding body. The horizontal grounding body is buried deep in the soil by 0.6 to 0.8 m, and the vertical grounding body is driven into the ground on the basis of the horizontal grounding body. The grounding lead wire adopts 40×4mm flat steel. For the convenience of inspection and safety of electricity, for the transformer installed on the column, the connection point of the lead wire should be located at the position of the channel under the transformer.

5. The landing line of the new and modified platform of the variable landing line should be multi-strand insulated wire. The cross section should be selected according to the rated capacity of the transformer frame, but the copper core of the high-voltage side drop wire should not be less than 16mm2, and the aluminum core should not be Less than 25mm2, eliminate the use of single stranded conductors and unqualified conductors. At the same time, the safety distance of the landing line to the surrounding buildings should be considered.