运城干式变压器：运城干式变压器过渡过程与电动力

运城干式变压器过渡过程与电动力 　　
运城干式变压器与油浸式运城干式变压器一样，从一种状态转换为另一种状态的过程称为过渡过程，出于过渡过程时间很短，故也称为瞬变过程。在瞬变过程中运城干式变压器的正常运行受到扰动，此时运城干式变压器铁心中的磁通密度及绕组中的电流密度发生变化，在过渡过程中呈现出它们的效应。
在运城干式变压器中有两种过渡过程，一是必须进行的，如干变投入运行时进行的空载合闸;二是运行中二次侧突然发生的短路故障，如在任一分接位置时线端突然短路。
空载合闸是干变运行的必经的一种瞬变过程;当二次侧突然发生短路故障，特别是线端发生三相短路时，运城干式变压器将受到大电流冲击，产生很大的电动力和过热。干变设计时，若短路强度不够，尽管瞬变过程持续时间很短.运城干式变压器绕组也可能发生变形，并因此而损坏。
我国对运城干式变压器瞬变过程与电动力开展了试验研究工作，在实践中对运城干式变压器结构进行了不断改进，且积累了丰富经验，形成了自己的设计方法.保证了运城干式变压器的机械强度。
运城干式变压器在空载合闸时.由于铁心饱和，磁密大增，合闸电流可增至稳定电流的几十倍甚至上百倍。
根据对运城干式变压器短路试验结果的分析可知，绕组损坏的主要原因是短路时绕组产生的辐向力和轴向力作用的结果。对于双绕组的运城干式变压器，沿绕组的轴向力使绕组承受压力或拉力作用，拉力方向是向铁轭，它由绕组的端部通过铁轭绝缘到铁心夹紧装置。当轴向拉力大于结构件机械强度时，可使绕组及夹件等铁心零部件产生变形，严重时可将上铁轭顶起.从而使铁心整个结构受到破坏。
沿绕组径向的辐向力，使内绕组承受压力.外绕组受到拉力作用，当拉力大于绕组导线的抗张应力时，可使绕组变形，匝绝缘可能断裂.即干变的主纵绝缘受到损坏，严重时可能拉断导线，
运城干式变压器短路时，短路电流要比额定电流大上百倍.在短路电流作用下除产生电动力之外.还会使绕组温度迅速升高。所以应在短时间内排除故降，若不能排出故障.则可能烧毁运城干式变压器、
由于短路电流产华盈非晶合金变压器有限公司生的电动力作用而造成的运城干式变压器损坏.多见于浸渍式干变。而树脂绝缘干变.由于绕组被绝缘树脂包封.尤其是绕包绝缘干变绕组，绝缘中的玻璃丝有很强的加强作用，使绕组的抗短路能力大为加强，在短路试验中几乎可以完全通过。

Dry-type power transformers transition process and electrical power

Dry-type power transformers oil-immersed transformer, called the transition process of transition from one state to another state, a short time out of the transition process, it is also known as the transient process. Disturbed in the transient process in the normal operation of the transformer, the current density changes in the magnetic flux density and in the windings of the transformer iron core, and exhibit their effects in the transition process.
There are two transitional process in the dry-type power transformer, must be put into operation, such as dry change load closing; sudden short-circuit fault running in the secondary side, as in either a tap position The isochron end sudden short circuit.
Load closing dry change run must pass through a transient process; suddenly short circuit fault, especially the line-end three-phase short circuit occurs when the secondary side of the transformer will be the impact of the high-current, resulting in a lot of electric power and overheating. Dry change design, short circuit strength, despite the transient process duration is very short dry type transformer winding deformation may also occur, and thus damaged.
Our experimental research work carried out on the the transformer transient process with the electric power, the continuous improvement in the practice of dry-type power transformer structure, and accumulated a wealth of experience, formed their own design. Guarantee a dry-type power transformer mechanical strength.
Dry-type power transformer load closing due to core saturation flux density greatly increased, the closing current may be increased to several times of the current stable or even a hundred times.
Based on the analysis of the transformer short circuit test results shows that, the winding main reason for the damage is the result of short circuit winding produces radial and axial force. The double winding dry-type power transformers, the axial force along the winding, winding to withstand the pressure or tension of the role, the direction of pull to a yoke of iron, by the end of the winding insulation to the core by a yoke of iron clamping device. Winding and clamps core parts can be deformed when the axial tensile force is greater than the mechanical strength of structural components, can be severe on the iron yoke from the top so that the entire core structural damage.
Along the winding radial radial force, pressure within the winding. Outer winding under tension when the tension is greater than the tensile stress of the winding wire, winding deformation can turn insulation may fracture the main longitudinal insulation dry change damaged, severe cases may pull off the wire,
Dry-type power transformer short-circuit, short-circuit current than the rated current on a hundredfold. Addition to generating electric power in the short-circuit current role but also the winding temperature rises rapidly. So should exclude so the drop in the short period of time may be burned transformer fault can not be discharged.
Dry-type power transformer damage caused due to the role of the electric power generated by the short-circuit current. Prevalent in the impregnated dry type transformers. Resin insulation dry change. Winding insulating resin encapsulation. Especially wrapped insulated dry transformer winding insulation of glass has a strong role in strengthening the winding resistance to short-circuit the ability to significantly strengthen in the short-circuit test almost completely through.

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