Chen Zunli (Shanghai Xinbo Fire-fighting Equipment Installation Co., Ltd., 200030) 1 - Starting an electrical fire in an air compressor room In the morning of June 2008, a fire broke out in the filling shop of a senior lubricants company. After investigation, the cause of the fire was caused by the failure of the electrical circuit in the air compressor room of the company and the paperboard piled in the air compressor room. 2 Abnormal heating of electrical equipment in air compressor room Most air compressors in enterprises are operated under full load or overload conditions, so abnormal heating of electrical equipment on air compressors is very common. Not only is it a hot summer, it is the same in winter. We once conducted infrared thermal imaging inspections at an auto parts company in Shanghai and found that the temperature of the low-voltage circuit breaker in the switch box of No. 2 air compressor reached 103.5 tons, and the temperature of another wire also exceeded 70 feet. Such as PVC sheathed cable, ordinary cable, flame retardant cable, the maximum allowable temperature of 70 feet, more than this temperature will accelerate the aging of the insulation layer, shorten the service life of the cable; rubber insulated wire allows the highest temperature is lower, only 65 The data shows that when the core exceeds the allowable temperature of 8~15t, the service life of the cable will drop by 25%~50%. If the insulated wire is in a high temperature state for a long time, scorching, cracking, insulation damage, insulation resistance drop, and serious It may cause leakage or short circuit or even fire accidents. According to the China Fire Statistical Yearbook, the proportion of fires caused by wire heating in China accounted for more than half of the total number of electrical fires. 3 Analysis of abnormal heating of electrical equipment in air compressor room Electrical equipment on the air compressor, such as low-voltage circuit breakers, contactors, wires and cables, are all supplied by air compressor manufacturers. The manufacturer may consider the air compressor's own overload capacity better, but the design margin is not considered enough for the supporting electrical equipment. Air compression is an exothermic reaction, so the temperature is relatively high in and around the compressor. I compared the thermal imaging data I captured, that is, in mid-November, the number of cable connectors for air compressor electrical switches exceeded one. For example, on November 2nd, 2006, when a thermal compression machine room of a plastic packaging company in Shanghai was used for thermal imaging of electrical equipment, it was once detected that there was 104 high temperature on the circuit breaker connection line; the same plastic packaging company was in Shenzhen factory. On July 10, 2006, the upper part of the air compressor circuit breaker measured a high temperature of 195.7 tons. Air compressor installation, materials and other factors. For example, when we conducted a thermal imaging inspection at a lighting company in Ningbo, it was found that the temperature of one phase in the lower pile head of an electrical main switch of an air compressor reached 93.7=1:. After inspection, it was found that the gasket had quality defects and the temperature dropped after the treatment. To 36.2 1, basically the same with the other two phases. This hidden danger has been there for 3 years. After the air compressor has been operated for a long time, the electrical resistance at the connection points of the electrical equipment may be excessive due to vibration, corrosion, oxidation, or heat, resulting in loose contact, oxidation, etc., resulting in excessive contact resistance. If there is a large current through the electrical circuit, it will cause a local temperature increase. When the contact point temperature increases, an oxide film is formed on the contact surface, which increases the contact resistance and forms a vicious circle. According to statistics from the US insurance company, electrical fires caused by poor contacts account for more than 25% of electrical fire accidents. According to the China Fire Statistics Yearbook, despite the fact that electrical fires caused by poor contacts accounted for only 12.6%, the direct or indirect causes of the short-circuit and overheating of the first and the second were also caused by poor contacts. As a chemical company of a Lubrizol Lubricants Co., Ltd., electrical equipment is vulnerable to corrosion by surrounding chemical gases, and the proportion of heat hazards caused by poor contact is high. When we conducted a thermal imaging inspection for a foreign-funded coating company in Shanghai, we found that there was a 15.5% report of thermal defects, which was much higher than the 8% ratio of the average company. There are 4 points with a temperature exceeding 1001, and the highest one is 150.8 feet. Some of the wires have already become discolored. 4 Measures to reduce electrical hazards in the air compressor room must begin with the selection, design, and equipment of the air compressor. Manufacturers of air compressors should appropriately increase the design margin when choosing air compressor electrical components and wires and cables, and design or construction units should also make requirements in this regard for manufacturing units. In this way, it can fundamentally reduce the electrical fire that occurs in the air compressor room. Stacking cardboard in an air compressor room indicates that a senior lubricants company is poorly managed. However, in high-risk enterprises such as flammable and explosive, it is not unusual for flammable and explosive materials to be stored around electrical equipment. On a certain day in August 2006, when we conducted a thermal imaging inspection at a bottle blowing plant of a foreign-funded plastics packaging company in Tianjin, we detected a maximum temperature of 164.8T for the electric wire of the control cabinet of a blowing machine. The wire has been severely aged and there is a short circuit at any time. And electrical fires are possible, and the equipment is surrounded by cardboard boxes and plastic products. Practice has proved that about 95% of electrical fire hazards can be discovered in time through thermal imaging. As long as periodic thermal imaging tests are performed, they can be promptly eliminated in the bud of electrical fires. Some chemical companies' flammable and explosive gases have a spontaneous ignition temperature of more than 1001. If the temperature exceeds 1001, it may become a necessary condition for an explosion or fire accident. In the analysis of modern security incidents, there is a "Hain's rule." Specifically, behind every serious aviation accident, there must be close to three minor accidents and more than 300 failed threats, and more than one potential accident. In order to eliminate this serious accident, we must control more than one accident. In fact, there is a "Hain's Rule" for any serious accident. Only by eliminating all security risks can major accidents be avoided. According to our many years of testing experience, the longer the service life of electrical equipment is, the more potential electrical thermal hazards will increase. 5 Conclusion Traditional electrical equipment inspections take "see, hear, touch, smell" And other methods use four of the five basic senses of human taste, sight, hearing, touch, and smell. The development of infrared technology has increased the human senses from five to six. The role of infrared thermal imaging technology in the inspection of electrical equipment can effectively compensate for the shortcomings of traditional electrical equipment inspection methods, thus avoiding or reducing the occurrence of electrical fire accidents. (Editing Shui Jia) Compressor Failure Safety Caused by Breakdown of Damping Resistance Caused by Damping Resistance Liu Xi, Inner Mongolia UMC Technician School, 012000) An enterprise adopts HCSFPZ-20000/35 type electric furnace transformer with a capacity of 20-times The side rated voltage is 35kV and the rated current is 330A. The production process requires the secondary side of the furnace to be directly connected to the electrode conductive jaw plate. The opening and closing of the power supply must be performed on the primary side. Therefore, the ZN23-40.5-1600 vacuum is selected. Circuit breaker as a power switch. In the preheating phase of the electric furnace, the primary winding is Y-connected and the working phase is A-connected. In order to increase the power factor of the equipment, a 7200 kvar reactive compensation capacitor bank is connected on the primary side of the transformer. When the electric furnace is in stable operation, the capacitor bank is thrown in and the capacitor bank is removed in advance. In order to prevent the damage caused to the equipment by shutoff over-voltage and re-ignition over-voltage in the switching operation of the switch, a resistance-capacitance absorbing device was installed on the primary side of the transformer. Use a three-phase damping and capacitance absorption circuit consisting of three BR35/-03-100 type damping resistors and three FFM35/-1 type protection capacitors. The wiring is as shown. 1 accident conditions and analysis According to regulations, each time the closing operation should lift any two of the three electrodes (reduced load), but the actual operation in order to process requirements often do not reduce the load, especially in the transformer When Y is connected, it is considered that the current is small and can be directly opened and closed. In the closing and closing operation, sometimes the damping resistance will give off A burst of sound with an arc, check for discharge traces on the damping resistor, and occasionally blown resistance wire. A problem was later found in the accident of two insulation breakdown cable terminals: which phase of the damping resistor has not been replaced, the cable termination of this phase may be broken down by insulation. According to the analysis, the resistance is disconnected, and the corresponding phase loses the capacity of absorbing and dissipating capacitance. When an overvoltage occurs, neither the capacitor absorbs energy nor the resistance damps overvoltage oscillation. In this way, the overvoltage increases the potential gradient of the transformer winding of the corresponding phase and the voltage at both ends of the vacuum interrupter and the cable termination to ground, breaking through the relatively weak part of the insulation. The damping resistor is a cylindrical non-inductive resistor wound on an insulating bracket with a bare resistance wire. It was found that some of the resistors were not brushed with insulating paint vertically on the top end. It was this unpainted slit that formed the discharge path, breaking the resistance wire and forming a cable terminal insulation breakdown accident. 2 Take measures to use adhesive paper to stick the two terminal surfaces of the resistor, and all the others shall be treated by dipping. In addition, operators are required to follow the procedures. (Edit Zhimin) furnace transformer failure BS 4346 Water Supply Fitting With Thread Pvc Male Plug,Pressure Pvc Male Plug,Pvc Female Thread Tee,Water Supply Upvc Male End Cap Zhejiang Huangyan Minghua Plastic Pipe Fitting CO.,LTD , https://www.pipefitting-mh.com