The oil-immersed transformer is to use oil as the main insulation means of a transformer, relying on oil as the cooling medium (self-cooling, air-cooling, water-cooling). When the oil volume of the transformer tank is above 1000 kg, oil storage or oil blocking facilities should be set. When set to accommodate 20% of the oil storage pit, the bottom of the pit should be equipped with an oil drainage pipe, the accident oil will be discharged into the accident oil storage pit.
The inner diameter of the oil drainage pipe should not be less than 150 mm, the oil should be discharged quickly when the accident occurs, and the mouth of the pipe should be equipped with an iron grille screen. When the above requirements cannot be met, oil storage or oil blocking facilities that can accommodate 100% of the oil volume should be set up. The oil storage pit should be larger than the equipment outline of each side by 1000 mm, and around the ground should be higher than 10Omm. The pit should be equipped with a net distance of not more than 40 mm grid, grid upper pebble layer, the thickness of the pebble layer should not be less than 250 mm, pebble diameter of 50 ~ 80 mm. The transformer foundation needs to be higher than the pebble layer by more than 100 mm. When set up with oil and water separation measures of the total accident oil storage pool, oil storage pool capacity should be determined by the largest oil tank capacity of 60%.
The part below the oil-immersed transformer is usually called the oil discharge pool or oil discharge pit, leading to the accident oil pit or accident oil pool. In the oil discharge pond, some do the fence, and some do not do the fence. To do the barrier, the pebbles are placed on top of the barrier. If you do not do the barrier, the pebbles are placed in the oil discharge pit. Do not do the barrier, with the transformer type, capacity, and voltage level related. When the transformer in operation suddenly exploded and caught fire, the oil ejected or discharged from the accident oil discharge valve, through the pebbles into the oil discharge pit, and then flow to the accident oil pool.
The role of the pebble layer
1. Fire prevention
The Pebble layer plays a role in isolation, reducing the fire, to facilitating the fire. In addition, high-temperature transformer oil through the pebbles after cooling can reduce the fire. Pebble layer also has a role is when the transformer oil on fire, fuel leakage to the pool, the fire source, and the transformer body isolation. Avoid the expansion of the fire accident.
2. Oil drainage
When the transformer is working abnormally, whether it is overeating or an internal short circuit causing pressure rise, the oil may be ejected from the pressure relief valve. Below the transformer is the oil pool, the oil will flow between the gaps in the transformer pebble layer to the oil pool below, the surface to avoid oil pollution, and to facilitate future maintenance or inspection.
3. Oil absorption
When the transformer's explosion-proof glass is broken, that is, when the transformer spray oil, absorbs the excess oil.
4. Overhaul
You can judge the oil leakage of the main transformer according to the oil stains on top of the pebbles, which is convenient for overhaul.
5、Insulation
The operation area of the substation equipment is equipped with additional operation insulation flooring, the stronger the adiabatic performance of the operation insulation flooring, the higher the safety protection for the operating personnel. Outdoor substations should not use the artificial green lawn, distribution device sites can use gravel, pebbles, or gray soil closed flooring treatment. When gravel and pebbles are used, no operation flooring is provided.
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