Safety of the hottest main power transformation an

Safety of main transformation and distribution equipment

1. Power transformer

power transformer is the core equipment of transformation and distribution station, which is divided into oil immersed transformer and dry-type transformer according to insulation structure

the flash point of oil used in oil immersed transformer is 135 ~ 160 ℃, which belongs to combustible liquid. The solid insulation liner, cardboard, cotton yarn, cloth, wood, etc. in the transformer are combustible substances, which have great fire risk and explosion risk

the installation of transformer shall comply with the following requirements: the fixation of each part and body of transformer must be firm; The electrical connection must be good; The grounding of the transformer is generally the ground shared by the neutral point of its low-voltage winding, the shell and its valve type arrester, which put the control cabinet down to the original position. The grounding must be good, and there should be a disconnectable connection point on the grounding wire; There shall be no combustible objects in front of the explosion-proof pipe nozzle of the transformer; When the transformer room is located underground, the door must be repaired in time, the door from the transformer room to the power distribution device room, and the door between the transformer rooms should be fire doors; The single capacity of oil immersed transformer installed in residential buildings shall not exceed 400 kV · a; The shell of 10 kV transformer shall be no less than 1 m from the door and 0.8 m from the wall (no less than 1.2m when equipped with operation switch); When natural ventilation is adopted, the ground of transformer room shall be 1.1 m higher than the outdoor ground; Outdoor transformers with a capacity of not more than 315 kV · a can be installed on columns, and those with a capacity of more than 315 kV · A should be installed on platforms

during operation, the voltage deviation at the high voltage side of the transformer shall not exceed 5% of the rated value, and the maximum unbalanced current at the low voltage shall not exceed 25% of the rated current. The upper oil temperature should generally not exceed 85 ℃; The cooling device should be kept normal, and the color of the moisture absorbent in the respirator should be light blue; The valve leading to the gas relay and the valve of the radiator shall be open, the diaphragm of the explosion-proof pipe shall be complete, and the doors and windows, ventilation holes, shutters, protection and lighting lamps of the transformer room shall be intact; The foundation of outdoor transformer shall not sink, and the pole shall be firm and not inclined. The installation site of dry-type transformer shall be well ventilated, and the relative humidity of the air shall not exceed 70%

power capacitor

power capacitor is an oil filled equipment, which may catch fire or even explode if it is installed, operated or operated improperly. At that time, many heavyweight guests will discuss hot topics at the carbon fiber and its composites forum, and leaving charge can also pose a direct threat to personal safety

the installation of capacitors should meet the following requirements: the ambient temperature of capacitors should generally not exceed 40 ℃, the relative humidity of surrounding air should not be greater than 80%, and the altitude should not exceed 1000 m; High voltage capacitors with a total oil volume of more than 300 kg should be installed in a separate explosion-proof room. High voltage capacitors and low-voltage capacitors with a total oil volume of less than 300 kg should be installed in intervals with explosion-proof walls or partitions depending on their oil volume; The capacitor should be protected from direct sunlight, and the window glass exposed to direct sunlight should be painted white; The capacitor room shall be well ventilated. Necessary ventilation conditions shall be ensured when the capacitor is installed in layers; Grounding (or neutral connection) measures shall be taken for capacitor shell and steel frame; Capacitors should have qualified discharge devices; When the total capacity of high-voltage capacitor bank does not exceed 100 kvar, it can be protected and controlled by drop type fuse; When the total capacity is 100 ~ 300 kvar, load switch protection and control shall be adopted; When the total capacity is more than 300 kvar, vacuum circuit breakers or other circuit breakers shall be used for protection and control. When the total capacity of low-voltage capacitor bank does not exceed 100 kvar, it can be protected and controlled by AC contactor, knife switch, fuse or knife switch; When the total capacity is more than 100 kvar, low-voltage circuit breaker shall be used for protection and control

during the operation of the capacitor, the current should not exceed 1.3 times the rated current of the capacitor for a long time; The voltage should not exceed 1.1 times the rated voltage of the capacitor for a long time; The temperature of capacitor shell shall not be higher than the specified value of the manufacturer (generally 60 ℃ or 65 C) until the spline twists and even breaks

3. High voltage switch

high voltage switch mainly includes high-voltage circuit breaker, high-voltage load switch and high-voltage disconnector. High voltage switch is used to complete the circuit conversion, which has great danger

high voltage circuit breaker is the most important and complex switchgear in high voltage switchgear. The high-voltage circuit breaker has a powerful arc extinguishing device, which can not only connect and disconnect the load current under normal conditions, but also cut off the overload current and short-circuit current under fault conditions with the help of relay protection devices. According to the arc extinguishing medium and arc extinguishing mode, the circuit breaker can be divided into less oil circuit breaker, more oil circuit breaker, vacuum circuit breaker, sulfur hexafluoride circuit breaker, compressed air circuit breaker, solid gas circuit breaker and magnetic blowing circuit breaker. The high-voltage circuit breaker must be used in series with the high-voltage disconnector. The circuit breaker connects and disconnects the current, and the disconnector disconnects the power supply

high voltage disconnector is abbreviated as knife switch. The disconnector has no special arc extinguishing device. It cannot be used to turn on and off the load current, nor can it be used to cut off the short-circuit current. The disconnector is mainly used to isolate the power supply to ensure the safety of maintenance and switching operation

the temperature of the connection part of the high-voltage disconnector in operation shall not exceed 75 ℃. The mechanism should be flexible

the high voltage load switch has a relatively simple arc extinguishing device, which is used to turn on and off the load current. The load switch must be used with the high-voltage fuse with high breaking capacity, and the fuse cuts off the short-circuit current. When the high-voltage load switch breaks the load current, there is a strong arc. Therefore, there must be no combustible in front of it