Transformer installation method steps and procedures

The transformer can be directly thrown into the transformer room by car crane, or set up a temporary track with wood, with three steps, chain crane to the temporary track, and then pull the chain into the appropriate position indoors. The transformer should pay attention to its orientation and distance from the wall size in accordance with the drawing, the allowable error is ±25mm, the horizontal distance from the wall should not be less than 800mm, the distance from the door should not be less than 1000mm when the drawing is not marked. Installation of transformer bench: the transformer is installed on the double pole, and the root of the two poles is open to 2m. The depth is 2m. The distribution transformer platform is fixed on two poles with two or four channel steels. The height of the platform from the ground is not less than 2.5m, and the plane slope of the platform 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 distance between the waist bar and the live part should not be less than 0.2m. At the same time, the high voltage cylinder of the transformer is equipped with a dust cover, and the transformer is suspended with a warning board.

Installation of drop fuse

Fuses shall be installed on the high and low voltage sides of the transformer respectively. The vertical height of the bottom of the high-voltage side fuse to the ground shall not be less than 4.5m, and the horizontal distance of each phase fuse shall not be less than 0.5m. In order to facilitate the operation and the fuse tube can fall down smoothly after the fuse is fused, the axis of the drop fuse should have an Angle of 15° ~ 30° with the vertical line. The vertical distance of the bottom of the low-voltage side fuse to the ground shall not be less than 5m, and the horizontal distance of each phase fuse shall not be less than 0.2m. The fuse of the drop fuse is selected according to the principle of "ensuring rapid fusing when the internal or high and low voltage outlet busings of the distribution transformer occur short circuit", and the fusing time of the fuse is less than or equal to 0.1s. According to the regulations: when the capacity is 100kVA or less, the rated current of the high voltage side fuse shall be selected by 2 ~ 3 times of the rated current of the transformer capacity; If the capacity is above 100kVA, the rated current of the high voltage side fuse shall be selected by 1.5 ~ 2 times of the rated current of the transformer capacity. The low voltage side fuse of the transformer is selected according to the rated current of the low voltage side.

Installation of lightning arrester

Selection of non-gap synthetic insulated jacket metal oxide arrester. The arrester should be installed between the fuse and the transformer, and as close as possible to the transformer. In addition, in order to prevent the invasion of reverse conversion wave and low pressure side lightning wave, low pressure arrester should also be installed on the low pressure side. In order to avoid the voltage drop of the lightning current on the grounding resistance and the residual voltage of the arrester being overlaid together and acting on the insulation of the transformer, the grounding end of the arrester, the shell of the transformer and the neutral point of the low voltage side should be connected together with a multi-strand copper core plastic wire with a cross section of not less than 25mm2, and then connected with the grounding device lead wire.

Ground grounding device

For 10kV distribution transformer: the capacity is below 100kVA, the ground resistance should not be greater than 10Ω; If the capacity is above 100kVA, the ground resistance should not be greater than 4Ω. The grounding resistance test shall be carried out after the construction of the grounding device, and the soil can be backfilled after passing the test. At the same time, the transformer shell is well grounded, the shell grounding should be tightened by bolts, not welded directly for maintenance. The underground part of the grounding device is composed of a horizontal grounding body and a vertical grounding body. The horizontal grounding body adopts 6 40×4mm flat steel with a length of 6m, and the vertical grounding body adopts 10-6 L50×50×5mm Angle steel with a length of 2m to weld with the horizontal grounding body respectively. The horizontal grounding body is buried in the soil at a depth of 0.6 ~ 0.8m, while 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 convenient detection and power consumption, the connection point of the lead wire should be located in the channel steel position under the transformer for the transformer installed on the column.

Change stage lead down line

The lead wire of the new and transformed transformer shall adopt multi-strand insulated wire, and its section shall be selected according to the rated capacity of the transformer. However, the copper core of the lead wire of the high voltage side shall not be less than 16mm2, and the aluminum core shall not be less than 25mm2. The use of single wire and unqualified wire shall be eliminated. At the same time, the distance of the lead line to the surrounding buildings should be considered.