For three-phase transformers installed above the second floor, the influence of vertical and horizontal transportation on the load of passages and floors should be considered. If dry-type transformer is used, its capacity should not be greater than 630kVA. The capacity of a single transformer in residential substation should not be greater than 630kVA.
(2) The oil-immersed power transformer installed inside should be installed in a separate cabinet. Detachable guardrails shall be installed on both sides of the high voltage side interval of the transformer.
There should be a channel entity door between the transformer and the low-voltage distribution room and transformer room. If wooden doors are used, one side of the transformer should be covered with iron. The transformer base shall be provided with shockproof measures, such as fixing fixtures.
The noise level of transformers should be strictly controlled, and measures such as installing noise reduction pads can be taken when necessary to meet the national environmental noise hygiene standards. Relevant living and working rooms should be ≤45dB(A) during the day and ≤35dB(A) at night.
(3) Voltage Regulation When the user system has voltage regulation requirements, an on-load automatic voltage regulation power transformer should be selected. It is suggested to adopt on-load automatic voltage regulating transformer in newly-built substation, which is beneficial to the economy of network operation. Although the temporary investment is slightly higher, the increased investment can be recovered in a short time.
When a substation with three voltages is needed, and the power passing through the coils on each side of the main transformer reaches more than 15% of the transformer capacity, the main transformer should adopt a three-coil transformer. Such as 220kV, 1 10kV and 35kV, three-winding transformers are usually used.
(4) When the following situations occur, a special transformer can be set up: When the power and lighting transformers are used, which seriously affects the lighting quality and bulb life, a special transformer can be set up. When the seasonal load capacity is large (such as the load of air conditioners and freezers in large civil buildings), special transformers can be set.
When the neutral current caused by single-phase unbalanced load exceeds 25% of the rated current of transformer low-voltage winding, single-phase transformer should be set. Some special equipment (such as large-capacity X-ray machine, etc. ) Due to functional needs, special transformers should be equipped.
Extended data
When using dry-type transformer, it should be equipped with winding thermal protection device, and its main functions should include: temperature sensor disconnection alarm, fan start/stop, over-temperature alarm/trip, maximum display of three-phase winding temperature inspection, etc.
Energy-saving transformers should be selected, the overload capacity of transformers should be considered when accidents occur, and forced air cooling measures can be taken when necessary. D, Yn 1 1 transformer should be selected when it is necessary to increase the single-phase short-circuit current value or limit the third harmonic content, or when the three-phase unbalanced load exceeds the rated capacity of each phase of the transformer by more than 5%.
Non-fuel transformer can be installed in an independent room or near the low-voltage side power distribution device, but measures should be taken to prevent personal contact. The shell protection level of non-fuel transformer shall be no less than IP2X.
Indoor oil-immersed power transformer should be installed in a separate cabinet. Detachable guardrails shall be installed on both sides of the high voltage side (including the upper cable) of the transformer.
There should be a channel entity door between the transformer and the low-voltage distribution room and transformer room. If wooden doors are used, one side of the transformer should be covered with iron. The transformer base shall be provided with shockproof measures, such as fixing fixtures.
The noise level of transformer should be strictly controlled. When necessary, measures such as installing noise reduction pads can be taken to meet the national environmental noise hygiene standards (related to living and working rooms), which should be ≤45dB(A) during the day and ≤35dB(A) at night.
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