Transformers can be directly thrown into the transformer room using a car crane, or temporary tracks can be set up with wooden tracks. Three steps and lifting chains can be used to lift the transformers onto the temporary tracks, and then the lifting chains can be used to pull them into a suitable position indoors. Transformers should pay attention to their orientation and distance from the wall, which should be consistent with the drawings. The allowable error is ± 25mm. If there are no markings on the drawings, the horizontal distance from the wall should not be less than 800mm, and the distance from the door should not be less than 1000mm. Installation of transformer stand: Install transformer on double pole with a root gap of 2m between the two poles. Buried at a depth of 2m. The distribution transformer stand is fixed to two poles with two or four channel steels, and the height of the stand from the ground is not less than 2.5m. The plane slope of the stand is not more than 1/100. The waist railing should be wrapped with iron wire with a diameter of no less than 4mm for more than two turns, and the winding should be firm. The distance between the waist railing and the live part should not be less than 0.2m. At the same time, dust covers are installed on the high-voltage column heads of the transformer, and warning signs are hung on the transformer.
Installation of drop type fuses
Fuses should be installed on the high and low voltage sides of transformers respectively. The vertical height of the bottom of the high-voltage side fuse to the ground should not be less than 4.5m, and the horizontal distance of each phase fuse should not be less than 0.5m. In order to facilitate operation and ensure that the fuse tube can smoothly fall down after fuse melting, the axis of the drop type fuse should be inclined at an angle of 15 ° to 30 ° with the vertical line. The vertical distance between the bottom of the low-voltage side fuse and the ground shall not be less than 5m, and the horizontal distance of each phase fuse shall not be less than 0.2m. The selection of the drop type fuse is based on the principle of "ensuring rapid melting in case of short circuit inside the distribution transformer or high/low voltage output bushing", and the melting time of the fuse is less than or equal to 0.1s. According to regulations, for those with a capacity of 100kVA or less, the rated current of the high-voltage side fuse shall be selected at 2-3 times the rated current of the transformer capacity; For transformers with a capacity of over 100kVA, the rated current of the high-voltage side fuse shall be selected at 1.5 to 2 times the rated current of the transformer capacity. The low-voltage side fuse of the transformer is selected according to the rated current on the low-voltage side.
Installation of lightning arrester
Choose a metal oxide lightning arrester with a seamless synthetic insulation jacket. The lightning arrester should be installed between the fuse and the transformer, and as close as possible to the transformer. In addition, to prevent the intrusion of reverse transformation waves and low-voltage side lightning waves, low-voltage lightning arresters should also be installed on the low-voltage side. To prevent the voltage drop of lightning current on the grounding resistance from overlapping with the residual voltage of the lightning arrester, which acts on the insulation of the transformer, the grounding end of the lightning arrester, the shell of the transformer, and the neutral point on the low-voltage side should be connected together with multiple copper core plastic wires with a cross-sectional area of not less than 25mm2, and then connected to the grounding device's lead wire.
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