Discussion on the fire fighting of power transform

2022-08-15
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Talking about the fire fighting of power transformer

as mankind enters the modern civilized society, the popularity of electricity goes deep into thousands of households and is widely used in all fields of society. With the development of production and science and technology, the requirements for electrical fire prevention are higher and higher. There are countless cases of fire caused by electricity every year, causing serious economic losses and casualties to the country and people. Power transformer is an important part of power supply system. There are the following common links: it can be said that where there are people, there is electricity; Where there is electricity, there is a transformer. In order to enhance the insulation performance of power transformation devices, most of them use insulating materials such as oil paper. If these insulating materials encounter sparks and arcs, they will not only burn themselves, but also form regional power cuts and fire accidents caused by them, which will bring great inconvenience to people's normal work, life and production. Moreover, when the transformer fires, the combustion spreads rapidly and it is difficult to put out the fire. When conditions permit, generally, the method of power-off fire extinguishing should be adopted. However, in the actual fire-fighting battle, if the fighter plane is lost due to waiting for the power-off, or the production is seriously affected due to the power-off, the method of live fire extinguishing should be immediately adopted to quickly and effectively control the fire and extinguish the fire. However, in our grass-roots Squadron, very few of the on-board equipment can extinguish the fire with electricity. Often, the fire brigade can only wait for the fire and sigh after arriving at the scene, and can only effectively implement the extinguishment and re welding after the power supply bureau arrives and cuts off power; Check whether there is a short-circuit point in the 5V load circuit? If any, remove the fire. Therefore, in order to better fight electrical fires, we must understand the structure, principle, fire causes, fire extinguishing measures and precautions of the transformer

I. structure and basic principle of transformer:

1. Structure of transformer:

A. transformer, also known as converter, is an electrical facility that converts high-voltage electricity produced by power plants into low-voltage electricity required by electrical appliances in the long-distance transmission of electric energy. It has various functions such as voltage transformation, current transformation, etc. According to the function of power transmission and distribution, it can be divided into step-up, step-down and distribution transformers. According to the different cold distribution media, it can be divided into air self cooling, dry type and oil immersed type. Among them, oil immersed transformer is the most widely used one, which is mainly composed of the main part (iron core coil), cooling part (oil tank, heat dissipation pipe), outgoing device (insulating sleeve and tap changer) and protective device (oil conservator, explosion-proof pipe, gas relay), etc

b. Working principle of transformer: wind one or three pairs of coils (single-phase or three-phase) on the closed iron core. The coil connected with the power supply is called the primary coil (primary or primary coil), and the coil connected with the load is called the secondary coil (secondary or secondary coil). When the primary coil is connected to the AC power supply, there will be current in the primary coil, which will generate alternating magnetic flux in the closed iron core Φ, This alternating flux Φ At the same time, it passes through the primary coil and the secondary coil. According to the principle of electromagnetic induction, the primary coil will generate self induced electromotive force, and the secondary coil will generate mutual inductance electromotive force. At this time, connect the bulb (load) to the secondary coil, the electric lamp will light up, and there will be current in the circuit. Add the safety engineer site to the favorites

2. Common fire causes of transformers: there is a large amount of insulating oil in the oil immersed power transformer, and there are a certain number of combustibles, such as cardboard, cotton yarn, cloth, wood, etc. if these organic combustibles encounter high temperature, sparks and arcs, they are easy to cause fire and explosion, resulting in the risk of fire in the transformer. For indoor transformers with oil content> 600kg, oil storage pits shall be set

1. The insulation of the internal coil is damaged and short circuit occurs due to poor manufacturing quality of the transformer, or maintenance errors, or long-term overload operation

2. Poor connection of the connector leads to excessive contact resistance and local high temperature fire

3. The iron core insulation is damaged, the full current increases, and the temperature rises, causing internal combustibles to burn

4. In case of short circuit or overload of electrical equipment, the transformer will overheat in case of failure of the protective device of the transformer or improper setting

5. The deterioration of transformer oil quality, or oil leakage and lack of oil in the oil tank, affects the thermal circulation of oil, reduces the heat dissipation capacity of oil, and leads to overheating and fire

6. The transformer is struck by lightning, which produces an arc or electric spark to ignite combustibles

7. If the animal is connected across the low-voltage bushing of the transformer, it will cause short circuit and fire

II. Fire fighting measures and precautions for transformer fire:

(I). Power off and fire extinguishing:

1. Technical measures for power off: in order to prevent electric shock accidents on the fire site, it is necessary to have the cooperation of electricians and technicians of the unit at first, and then there should be special power off equipment. When cutting off the power supply, the following technical measures should be taken:

a. Disconnect the main switch in the substation

b, cut off the power supply with a falling fuse

c, request the power supply bureau to cut off power in the area where the transformer is located

2. Fire fighting measures after power failure: in case of transformer fire, the fire fighting method after cutting off the power supply is the same as that for combustible liquid fire

a. if the oil tank is not damaged, dry powder, 1211, CO2 and other fire extinguishing agents can be used to put out the fire

b. if the oil tank breaks, a large amount of oil flows out and burns, and the fire is fierce, you can remove the self weight of the spring and put out the fire with spray water or foam after cutting off the power supply. The scattered oil fire can also be buried with sand. When it is maximum, you can dig ditches to put out the oil with foam

c. Large substation equipment has many beautiful insulating bushings. When these bushings encounter rapid cooling or uneven cooling at high temperature, they are easy to burst and damage the equipment, which may cause unnecessary losses. If the bushing with insulating oil bursts, it will also cause the insulating oil to disperse, which will further expand and spread the fire. Therefore, in this case, it is best to use spray water to extinguish the fire, and pay attention to the uniform cooling of the equipment

(II) live fire fighting:

in the fire fighting battle, we often encounter the situation that the equipment is live, and some situations are urgent. In order to win the fighter, we must carry out fire fighting under the condition of live. Sometimes when it is impossible to cut off the power supply due to production needs or other reasons, or when there is still a high residual voltage after cutting off the power supply for the sample, it is also necessary to put out the fire with electricity. The key to putting out the fire with electricity is to solve the danger of electric shock. When various safety measures are taken, the fire fighting method for the live transformer is the same as that after power failure

1. Live fire extinguishing with fire extinguishers:

① common fire extinguishing agents and minimum safe distance: common fire extinguishing agents include CO2, 1211, dry powder, etc., which are non-conductive and have sufficient insulation capacity. For the sake of safety, we should ensure that the minimum safe distance between the human body and the charged body should not be less than 3m

②. Precautions: first, pay attention to the operation essentials and use requirements; Second, try to spray in the upwind

③ keep the minimum safe distance

2. Start the fire extinguishing device to extinguish the fire with electricity:

fixed or semi fixed fire extinguishing devices are installed, which plays an important role in extinguishing the initial fire in time, protecting equipment and preventing the spread and expansion of the fire. At present, the fixed fire-extinguishing devices used in power plants and power supply systems include steam, 1211 and mist water, but in terms of the current situation in China, there are almost no fixed fire-extinguishing devices installed in outdoor transformers

①, 1211 devices. 1211 fire extinguishing device is commonly used in the transformer in the substation. Its nozzle is installed around the oil storage at the upper and lower parts of the transformer, so that the fire extinguishing agent can be sprayed into the combustion area with emphasis

② water spray fire extinguishing device: in reality, it is only for indoor large and important substation equipment, machine room and power supply system. It adopts automatic control system, which can automatically alert and extinguish fire in case of fire

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