Abstract Global Wang Xiao Xiao Bian finishing the 2020 Middle Safety Engineer Q & A: Transmission Line Icing and Remedies What?,For reference!View more content please pay attention to the pro forma Global Wang Xiao Middle Safety Engineer channels, and have fun learning!
problem:
Transmission Line Icing and Remedies What?
Q & A:
1, the transmission line Icing reasons
Lu Di transmission line icing in winter and early spring (temperature is about minus five degrees), or in the snow or rain and snow weather Cross, in Lu Di wire transmission line, lightning line, etc. Insulator string will have to be ice, cream are mixed to form the wet snow and ice.This is a layer of solid but transparent or translucent tightly ice, ice is formed overlying the reason, because water droplets adhered on the nature of the object, when the temperature drops, the drops will condense into ice, and the thicker end.
Sometimes, also on the surface of the conductor layer of frost on the junction, it was nuggets properties which are much lighter than the weight of the solid ice,
However, the thickness is much larger.Usually, when there is a lot of moisture in the air and there is a breeze, most likely to form flute.
When wet snow falling, wet mine on the one hand glued to the wire, and will penetrate the wood is frozen, the ice more
Thick, the thickest of up to 10 cm.
When the line is parallel with the wind direction, the ice elliptical cross section; and when a line perpendicular to the wind direction, fan-shaped cross section of the ice, i.e. at the side surface of a ground conductor; when no wind, ice is a layer of uniformly.
In addition, icing is also related to the line, the cold and hot air through the intersection of the line, the more serious icing.Trade and ice remain on the wire or Insulator local time is different, the temperature reached depends mainly on the ground level and the size of the wind, as short as a few hours or as long as up to a few days.
2, the accident occurred due to icing
Lightning conductor and ground line under ice load is very thick to sometimes, in severe exceed the design line.If the wire, lightning line icing occurs Shihai accompanied by a strong wind, but also to increase its load, which may cause a lightning conductor or line break, with the gold and destruction Insulator string, so that even damage the tower.Particular sector ice, which enables the wire is twisted, so the fittings and the maximum Insulator string threaten.Common ground icing accidents are the following:
(1) tower damage due to icing, generally due to a conductor break straight tower caused by the side.At this time, since the wires are formed with iced largely tension tower to the other side of the tower by an excessive load, it causes the lever down or inverted column accident.
(2) icing accident, if the wire is arranged vertically in the tower, when the wire line and the lightning ice has partial loss, due to non-uniform load to each wire, the wire will Faquan jumping phenomenon, so that wire collision, causing a short circuit fault.
(3) each span line icing accident caused by uneven, since each of the line span ice interior unevenness and other reasons, each span will vary greatly interior vertical arc occurs.Severe icing to span large inland wire load, will lead a serious sag, so sometimes the distance from the ground to reduce the lead to a very dangerous extent, thus accident.
(. 4) ice management Insulator string accident, although the increase in ice thickness on Insulator little to the weight, but reduces the insulation to the insulation level of the string, ground fault cause flashover, even burn Insulator, very serious consequences.
3, prevent and eliminate icing measures
In order to prevent icing of the earth faults, tower design, consideration should be given to a load applied due to the ice formed.Regular area to severe icing, anti-icing formula erected to line providing a large tower to tower than the average mechanical strength, short span, small wire tension.To avoid collision, wires should be arranged horizontally disposed method, and should be appropriately increased linear distance between the conductor and lightning.
When the path select line, to be noted that to avoid the cold and hot air Interchange.
But in the ice particular area seriously, these measures are not enough, the ice can still cause damage to the line accident.Therefore, we must observe produce ice to the situation on the lead in the operation, and to take appropriate measures to eliminate.
Elimination of ice on the conductor, current and mechanical fusion method knocked.
(1) Current melting method
This method is mainly used to increase the load current or short circuit current to the heating wire so that the melting ice floor, to head reaches deicing.Specifically the following three:
① by changing the operation mode to the power grid to increase the current load circuit.
② the line disconnected from the system, and three-phase short circuit to one end of it, with the other end to a transformer or an ad hoc short-circuit current is supplied to the generator.
③ When the load current is increased to heat the conductor line to practice employed, should start at the beginning of ice formation, ie to increase the load current, as a precaution.However, this approach would be the line voltage drop, power loss increases, it is not used for a long.
When the short-circuit method used to melt ice, it should be based on the line length, the cross section of the wire material and the team, and prepare the device are necessary, which capacity should be calculated in advance, so as to meet the requirements of the melting ice.
(2) mechanical deicing
Mechanical deicing is primitive, the de-icer is also not the same style each region, its many types, mechanical deicing main drawback is the need for power, time-consuming, laborious.When using mechanical deicing, and lightning conductor must ensure that any mechanical damage occurs line.
① short throw stick to the wire from the ground or a lightning conductor, breaking ice, so that off.It may be tapping with a wooden or bamboo the ice off.If the power lines can also be difficult to beat the insulating rod ice.
② on the wire, and pull down the wire snare with a rope with a wooden cover, can eliminate icing.
③ with pulley deicer deicing.
Above is the 2020 Middle Safety Engineer Q & A: Transmission Line Icing and Remedies What?For your reference learning!To help candidates timely access to 2020 Intermediate safety engineer exam registration time, you can click on.
View more mid-level registered safety engineer pro forma below the article content can click “click free download Security Engineer Examination / test sites essence” more free content all in one.