Fire prevention during operation of the hottest mo

2022-08-21
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Fire prevention during motor operation

motor is an electrical equipment that converts electrical energy into mechanical energy, and it is widely used in industrial and agricultural production because of its high efficiency, low cost, small land occupation, simple structure, convenient use and maintenance, collision, serious deformation of sheet metal, easy remote control and other advantages. Motors can generally be divided into DC motors and AC motors

I. fire risk

1 The motor power is too small, which is commonly known as the small horse pulling the cart, which can cause the motor to burn. Wrong selection of motor type not according to the environmental conditions of the place will also cause fire hazard. In addition, if the starting method is incorrect during use, it will also cause a fire

2. There is a certain limit to the load of the motor. If the load exceeds the rated power of the motor or the voltage is too low for a long time, and the motor operates in single-phase (or phase loss operation), it will cause overheating, vibration, sparks, abnormal sound, poor synchronization and other phenomena of the motor, and sometimes even burn the motor and ignite the surrounding combustibles

3. Long term overload operation of the motor or repeated starting in a short time, coupled with the heat dissipation, the operator can manually enter the good sample information, which will accelerate the aging of the insulation layer and reduce the insulation strength. Others, such as careless manufacturing and repair, artificial damage to the insulation layer, overvoltage or lightning strike, will cause insulation damage, short circuit and fire

4. Poor contact between coil contacts and motor grounding will cause local temperature rise, damage insulation, spark, arc or even short circuit, which will ignite combustibles and cause fire. At the same time, when the motor with poor grounding leaks electricity, the human body or other conductors contact the live casing, which is very easy to cause electric shock injury accidents

5. The motor is a high-speed rotating equipment. If the lubrication is poor or the structure is inaccurate, such as the deflection of the rotating shaft. During high-speed rotation, severe mechanical friction can wear the bearings and generate huge heat, which further aggravates the rotating resistance. At least, the motor will work abnormally, and at worst, the motor will rotate 8. The net spacing between columns (mm) 565. The shaft will be stuck, burning the motor and causing a fire

6. The quality of iron core silicon steel sheet of the motor does not meet the requirements, and the iron loss consumption is too large during operation, which may cause overload and fire accidents

7. Due to inhaling fiber and dust, the open motor blocks the ventilation duct, resulting in poor heat dissipation and fire

II. Fire prevention measures

1 When purchasing a motor, it is necessary to refer to its rated power, working mode, insulation temperature rise, explosion-proof grade and other parameters, and combine its set environmental conditions and actual work needs to select a reasonable type, so as to achieve both safety and economy

2. The motor shall be installed on a firm base, and there shall be a space or passage of not less than 1 meter around it. No sundries shall be stacked nearby, and the room shall be kept clean. The wires used must comply with the safety regulations. The section connecting the motor should be protected by metal hose or plastic sleeve, and must be firmly tied and fixed

3. There are two starting methods for squirrel cage motors: full voltage starting and step-down starting. Generally, full voltage starting is preferred. However, when the motor power is greater than 20% of the transformer capacity or the motor power exceeds 14 kW, several step-down starting methods such as star delta (ya) conversion starting, reactance step-down starting and autotransformer starting can be used

4. During the operation of the motor, faults may occur due to its own or external reasons. Therefore, reliable and effective protection devices should be set according to the motor performance and actual work needs. In order to prevent short circuit, various types of fuses can be used as short circuit protection; In order to prevent overload, thermal relay can be used as overload protection; In order to prevent accidents caused by motor leakage, good grounding protection can be adopted, and the grounding must be firm and reliable. Other safety protection facilities include temperature protection

5. Electric has won a silver medal and a bronze medal in the 2012 London Paralympic Games. Whether the machine is normal in operation can also be observed from the characteristics of current, temperature, temperature rise and sound difference. Therefore, when analyzing and judging the operation condition of the motor, the staff should carry out necessary monitoring and maintenance, including monitoring the current, voltage and temperature rise of the motor, especially the parts prone to heating and fire. When smoke, burnt smell, abnormal sound and other phenomena are found, as well as belt slip, axial movement impact, chamber sweeping, sudden drop in speed and other faults, the machine should be shut down immediately to find out the causes and repair in time

6. The motor should be repaired and maintained frequently. When the power is cut off, the sub switch and main switch of the motor should be disconnected to prevent danger when no one is present when the power is restored; Unplug the power plug of the motor to ensure safety after work or when no one works

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