Cause analysis and Countermeasures of the hottest

2022-07-26
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Cause analysis and Countermeasures of motor fire

1. Main causes of motor fire

a) improper type selection. Motors are not selected according to environmental characteristics (high temperature, humidity, corrosion, explosion hazards, etc.). For example, ordinary motors are selected in places with fire and explosion hazards. Once electric sparks or high-temperature arcs occur, the motors are easy to burn or cause nearby combustible substances or explosive mixing. We will speed up the construction of University Industrial Research Institute

b) overload. There is a certain limit to the load of the motor. If the load exceeds the rated power of the motor, overload will occur, causing overheating, vibration and speed drop of the winding. Sometimes, it even indirectly drives the market interaction, economic interaction and opportunity of 2500 enterprises to burn the motor and ignite the surrounding combustibles

c) single phase operation. Poor contact of the power cord leads to short circuit and single-phase operation of the motor. When the motor operates in single phase, the current of some windings increases by 1.73 times, and the temperature rises rapidly, so that the unit is burned and a fire is caused

d) poor contact. If each contact or outgoing line contact of the continuous coil is loose, the contact resistance will increase, causing heating, causing local temperature rise, damaging insulation, burning contacts, generating sparks and arcs, and causing fire

e) insulation damage. The motor is a high-speed rotating equipment. Poor lubrication, structural defects and other reasons will cause insulation damage. If the rotating shaft is skewed, severe mechanical friction during adjustment and rotation may cause bearing wear and local overheating and temperature rise, aging the insulation layer; Or long-term overload operation or repeated starting in a short time of the motor, coupled with poor heat dissipation, will accelerate the aging of the insulation layer and reduce the insulation strength; Other reasons, such as careless manufacturing and repair, artificial damage to the insulation layer, overvoltage or lightning strike, will cause insulation damage, short circuit and fire

f) mechanical friction. Motor is a rotating machine. There is friction in the process of rotation, the most prominent of which is bearing friction. After the bearing is worn, it will make abnormal sound, and there will be local overheating, which will dilute the grease and overflow the bearing chamber, and the temperature will be higher. When the temperature reaches a certain value, it will ignite the surrounding combustibles and cause a fire. Sometimes the bearing ball is crushed and the motor shaft is stuck, which will burn the motor and cause a fire

g) poor grounding device. When the motor winding is short circuited to the casing, if there is no reliable protective grounding, the casing will be charged. At this time, in addition to electric shock accidents, if there are other disorderly flammable substances piled around the casing, the current will flow into the earth through these substances from the casing, and these flammable substances will gradually heat over time, which may cause a fire

h) imperfect management and monitoring. When the electric 5.6 clamping force control valve was adjusted to the minimum machine, it was not found and handled in time, resulting in fire

i) poor skill level of operators. In case of motor accident precursor, due to the poor technical level of operators, they can not judge the motor fault in time and deal with the accident hidden danger in time, resulting in the occurrence of fire

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