Fire fighting of the hottest power transformer

Fire fighting of power transformer

as human beings enter the modern civilized society, the popularity of electricity goes deep into thousands of households and is widely used in various 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. 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 work, life and production when setting the conditions for the end of the experiment. 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 a friend doubts and waits for the power-off soon and loses the fighter, or the production is seriously affected by the power-off, the method of live fire extinguishing should be adopted immediately to control the fire quickly and effectively and extinguish the fire. But in our grass-roots Squadron, few of the on-board equipment can extinguish the fire with electricity. Often, the fire brigade can only sigh at the fire after arriving at the scene, and can only effectively extinguish the fire after the power supply bureau arrives and cuts off power. 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), the fourth sub part of the 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

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. The poor connection of the joint causes excessive contact resistance. The high-strength bolt test fixture is mainly the tensile test fixture and wedge load test fixture, causing 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