The busbar of indoor high and low voltage switchgear sets refers to the conductors used in the switchgear sets to connect the cabinets and all electrical equipment inside the cabinets to collect, distribute and transmit electric energy. In the case of short circuit fault, it should bear the heating and electric power caused by short circuit current. The following small make up a detailed explanation of the high, low voltage switch cabinet bus influencing factors.
The switchgear cabinet is divided into three kinds of bus according to its cross section: rectangular, circular (or double D) and groove bus. When the cross section area of the bus is the same, the perimeter of the rectangular bus is larger than that of the circular bus, and its heat dissipation effect and cooling condition are good. Moreover, at a certain allowable temperature, the current passing through the rectangular bus is larger than that of the circular bus, and the skin effect of the circular bus is stronger, while the rectangular bus is more uniform. Therefore the complete set of switch cabinets are generally used in the rectangular bus.
Switch cabinet bus phase sequence position and international color comparison table: * h(g) o! S4 [7 F4 e2 g; K% s2 i#} cabinet body ground bus: yellow and green alternate (if it is copper, can adopt the color, paste the ground mark). F# O(E" w4 u% u: a1 uLayout of bus in cabinet:
(1) according to the vertical or horizontal "one" shape, such as ggla-12f type and gbc-40.5 type, the cabinet top main bus line layout structure;
(2) according to the shape of "product" or triangle: for example, kyn28a-12, kyn61-40.5 main bus line layout structure.
Factors affecting bus carrying capacity:
A. arrangement: vertical and horizontal, vertical dynamic stability current value is larger than horizontal.
B. Ambient temperature (the temperature value in the table below is the maximum temperature value that bare bus can bear).
C. material of bus: copper; Aluminum; Steel. Copper, which has the highest conductivity and the largest carrying capacity at the same cross-sectional area, and steel, which is the smallest, is often used in PT or arrester circuits.
D. the number of busbars: when multiple busbars are arranged side by side, the heat dissipation condition is much worse than that of a single busbar.
For example, the current test value of LMY100X10: the single carrying capacity is 1728A/1(as the reference); In the case of double-root arrangement, the carrying capacity is 2558A/1.48. When three roots are arranged, the carrying flow is 3181A/1.84. When the four pipes are arranged, the carrying capacity is 3622A/2.09.
E, heat dissipation conditions: open switch cabinets than closed switch cabinets used in the bus load capacity to be large, with air conditioning substation than no air conditioning is better.
Bus is also a function of insulation: to prevent contact with small animals caused by the phase or relative short circuit fault, prevent pollution flashing or condensation flashing, prevent human casualties, prevent salt fog and harmful chemical gas direct corrosion of the bus.
The insulation mode of bus is:
(1) heat-shrinkable sheath: it can improve the insulation level between the busbars, but the sheath has the problem of insulation aging, and the heat dissipation condition of the busbars will also become worse, which increases the production cost.
(2) cold shrinkage sheath: easy to operate, no need to heat. However, the cost is high, and there are aging insulation and bus cooling conditions.
(3) vulcanization spraying: the production process is complex, when the collision can not be remedied, the connection of the bus can not be sprayed.
(4) SF6 gas insulation: fill 0 in the sealed main busbar room and circuit breaker room. 04Mpa SF6 gas can improve the insulation performance between bus; The main bus does not need to be repaired and maintained in the whole life cycle, and is not affected by the external environment, so it is safe and reliable. However, the production process is complicated, which is the main insulation mode of the c-gis gas-filled cabinet at present.
(5) installation of partitions: when the clear distance between phases or relative to the ground cannot reach a safe distance, insulation partitions can be installed between phases or the ground. SMC: according to the requirements of national standard insulating clapboard and charged body of minimum distance requirement is: 12 kv switchgear ≮ 30 mm.
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