Transformer Installation Procedure

The transformer may be lifted directly into the transformer room using a truck crane, or temporarily laid on a track made of sleepers, hoisted onto the temporary track using a three-step support and chain block, and then pulled into the appropriate position within the room using the chain block. Attention should be paid to ensure that the transformer's orientation and its distances from the walls comply with the drawings, with an allowable deviation of ±25mm. Where not specified in the drawings, the horizontal distance from the wall shall not be less than 800mm, and the distance from the door shall not be less than 1000mm.

Transformer Platform Installation:

For transformers installed on double-pole structures, the distance between the two poles is 2m, with an embedment depth of 2m. The distribution transformer platform is fixed to the two poles using two or four channel steels. The platform height above the ground shall not be less than 2.5m, and the platform slope shall not exceed 1/100. The binding wire shall be made of iron wire with a diameter of not less than 4mm, wound around at least two turns, tightly secured, and shall be at least 0.2m away from live parts. Additionally, a dust cover shall be installed on the transformer's high-voltage bushing, and a warning sign shall be hung on the transformer.

Installation of Drop-Out Fuses

Fuses shall be installed on both the high-voltage and low-voltage sides of the transformer. The vertical height from the bottom of the high-voltage side fuse to the ground shall not be less than 4.5m, and the horizontal distance between fuses of each phase shall not be less than 0.5m. To facilitate operation and ensure the fuse tube can fall freely after the fuse element melts, the axis of the drop-out fuse shall form an angle of 15° to 30° with the vertical line. The vertical height from the bottom of the low-voltage side fuse to the ground shall not be less than 5m, and the horizontal distance between fuses of each phase shall not be less than 0.2m.

The fuse element selection for drop-out fuses shall follow the principle of "ensuring rapid melting in the event of a short circuit inside the distribution transformer or on the high/low-voltage outlet bushings," with a melting time of ≤0.1s. In accordance with regulations: for transformers with a capacity of 100kVA or less, the rated current of the high-voltage side fuse element shall be selected at 2 to 3 times the transformer's rated current; for transformers with a capacity above 100kVA, the high-voltage side fuse element shall be selected at 1.5 to 2 times the transformer's rated current. The low-voltage side fuse element shall be selected based on the low-voltage side rated current.

Installation of Lightning Arresters

Metal-oxide surge arresters with gapless composite insulation housings shall be selected. The arrester shall be installed between the fuse and the transformer, as close to the transformer as possible. Additionally, to prevent reverse conversion waves and low-voltage side lightning surges from intruding, low-voltage arresters shall also be installed on the low-voltage side. To avoid the superposition of the voltage drop across the grounding resistance caused by lightning current and the residual voltage of the arrester acting on the transformer insulation, the grounding terminal of the arrester, the transformer tank, and the low-voltage side neutral point shall be connected together using stranded copper-core plastic-insulated wire with a cross-section of not less than 25mm², and then connected to the lead-in wire of the grounding device.