Fire and prevention of the hottest motor

Motor fire and prevention

motor is an electrical equipment that converts electrical energy into mechanical energy. The cause of fire is mainly caused by improper type selection, use, or poor maintenance. Some motors have poor quality and internal hidden dangers, which are very prone to failure during operation and cause fire

the main ignition parts of the motor are windings, leads, iron cores, brushes and bearings. The main causes of fire during its use are:

(I) overload

the maximum power of the motor is limited. If the load exceeds the rated output power of the motor, overload will occur. Low voltage will also cause overload. Once overload occurs, it will inevitably cause the winding to overheat, even burn the motor, or ignite the surrounding combustibles, causing a fire

(II) insulation damage

if the wire insulation of the motor is damaged, it will cause inter turn short circuit or inter phase short circuit; If the insulation between the winding and the casing is damaged, it will also cause a short circuit to the ground and a short circuit fire

(III) poor contact

if each contact of the connecting coil is loose, the contact resistance will increase, and it will be heated when passing the current. The hotter the contact is, the faster the oxidation is, and the greater the contact resistance is. Such repeated cycles will finally burn the point, generate electric sparks, the demand for rubber is rising every year, arc, or damage the insulation of the surrounding wires, resulting in short circuit and fire

(IV) improper selection

different forms of sjsz series conical twin-screw extruders should be selected for different occasions. They have the characteristics of forced extrusion, high quality, wide adaptability, long service life, low shear rate, material not easy to decompose, mixing and plasticizing performance. Dow pacxpert technology has collected all the eight strength awards in the global packaging industry, and powder direct molding, so as to meet the needs of production and safety. For example, in places with fire and explosion hazards, protective motors are selected. When the motor fails, the high temperature, arc and spark generated will ignite combustible substances or detonate explosive mixtures, causing fire and explosion. If protective motors are selected in wet places, the insulation is often damaged and the motor is burned because the winding is damp

(V) single phase operation

the three-phase asynchronous motor continues to operate when one phase is not energized, which is extremely harmful, ranging from burning the motor to causing a fire

(VI) mechanical friction

motor is a rotating machine, and there is friction in the process of rotation, the most prominent of which is bearing friction. After the bearing is worn, it will make an 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, the motor shaft is stuck, and the motor is burned, causing a fire

(VII) excessive iron loss

during the operation of three-phase asynchronous motor, there will inevitably be iron loss, that is, hysteresis loss and eddy current loss caused by alternating magnetic flux in the stator core. Hysteresis loss is reactive loss, while eddy current loss is active loss, resulting in core heating. If the quality and specification of iron core silicon steel sheets do not meet the requirements, or the insulation strength between sheets is too low, the eddy current loss will be too large. At this time, its no-load current can reach more than 50% of the rated current. If the motor drives the load, overload will inevitably occur

(VIII) poor grounding device

when the motor winding is short circuited to the housing, if there is no reliable protective grounding, the housing will be charged, and in case of inadvertent contact with the housing, it will cause an electric shock accident. If there are other messy inflammable substances piled around the enclosure, the current will flow into the earth through the enclosure, and it will gradually heat over time, which may cause a fire

II. Preventive measures for motor fire

as long as the structural form of the motor is properly selected, the head is installed, reliable protective devices are deployed, and the monitoring of the operation is strengthened, when the design structure is enough to be put into the computer host and can be put into the display device, the fire accident caused by burning the motor can be reduced. The specific measures are:

1 Select the corresponding models (closed, open, explosion-proof) according to the specific environment of the motor (high temperature, humidity, corrosion, gas, explosion hazardous places, etc.)

2. Select the capacity of the motor according to the load

3. Select the speed of the motor according to the mechanical speed of the load

4. Pay attention to the connection method, and select the tail line section. Fuses and switches are mounted on non combustible bodies

5. Carry out regular maintenance to prevent overload and two-phase operation

6. Do not stack flammable and combustible substances around