The influence of external environmental factors on the life of electrical equipment
According to incomplete statistics, the current external environment factors caused by the electrical equipment failure accounted for 62% of the overall fault of the device, design and device defects of 18%, the use of maintenance factor of 11%, other factors: 9%.
Temperature influence
In the operation of electrical equipment, if the temperature is too high or too low, exceeding the allowable limit, may have a fault.
1.1 effect on conductor material
With the increase of temperature, the softening of the metal material and the mechanical strength will decrease obviously. For example, the mechanical strength of copper metal material decreases obviously when the working temperature is over 200 degrees. The mechanical strength of aluminum alloy material is also closely related to the temperature, usually the long-term working temperature of aluminum should not exceed 90 DEG C, short working temperature should not exceed 120 degrees C. If the temperature is too high, the organic insulation material will become brittle and aging, the insulation performance will decline, even the breakdown.
1.2 effect on electrical contact
Poor electrical contact is responsible for many failures
1.3 impact on components
In a sense, in the case of damage, the effect of temperature on the electrical components are mainly embodied in the zero drift and linearity, resulting in a decline in high temperature, heat dissipation device temperature rise, more than the limit will occur when the breakdown, short circuit or open circuit device damage fault.
The first is the thermistor and electrolytic capacitors, electrolytic capacitors at low temperatures (how many degrees will be different), the capacity value will be reduced by half or even capacity. When the temperature is high, the life will plummet, so all the electronic products are calculated according to the electrolytic capacitor.
Two, humidity influence
The vast majority of electrical equipment are used in dry conditions and storage of low humidity (especially dry environment) will produce static electrical equipment for use in adverse, need to control the appropriate humidity range.
According to statistics, every year more than 1/4 of the world's industrial production of harmful substances and wet. For the electronics industry, the harm of moisture has become one of the main factors affecting the quality of products.
2.1 impact on integrated circuits
Moisture on the semiconductor industry, the main damage in the wet through the IC plastic package from the pin and other cracks into the interior of the IC, resulting in IC moisture absorption. Water vapor is formed in the heating process of the SMT process, resulting in the cracking of the IC resin encapsulation, and the oxidation of the inner metal of the IC device, which results in the failure of the product. In addition, when the device is in the welding process of PCB plate, because the water vapor pressure release, will also lead to.
2.2 effects on liquid crystal devices
Glass substrate and polarizer, liquid crystal display and liquid crystal device filter in the production process to be cleaned while drying, but its effect will still be affected by moisture after cooling, reducing the rate of qualified products. Therefore, in the dry cleaning should be stored in the following 40%RH dry environment.
2.3 effects on other electronic devices
Capacitors, ceramic components, connectors, switches, solder, PCB, crystal, silicon wafer, quartz oscillator, SMT glue, electrode material adhesive, electronic slurry, high brightness device, are subjected to wet damage.
Electrical equipment from humidity hazards during use, if used for a long time in a high humidity environment, will lead to failure, the computer board CPU will make the gold finger oxidation leads to poor contact failure.
Most of the use of electrical equipment environmental humidity should be below 40%.
Three, dust influence
The influence of dust control system of electrical equipment and other electronic components reliability, to shorten the service life, ensuring the quality of products, the working conditions and environment becomes worse, all the dust and waste gas cause harm to human body.
Taking as an example to discuss the impact of metallurgical dust dust on electrical equipment:
It is inevitable to produce a large amount of harmful dust in metallurgical production. The production of dust not only pollutes the environment, but also damages the health of people.
3.1 cause electrical equipment short circuit
The dust in metallurgical production mostly mineral dust and metal dust, and the dust resistance is not high, such as sintering machine dust resistance of 1.47 * 10~9.06 * 10. Cm, and because the dust particle charge (floating in the air of dust particles are 90% 95% positively charged or charged), water (water quantity and environmental temperature and humidity), it is easy to make the dust settling around the agglutination of electrical equipment, thereby reducing the electrical distance, the insulation strength, or electrical operation online overvoltage of electrical breakdown short-circuit accident caused extremely easily in the process of electrical equipment failure. If the total step-down station for steelmaking plant and close, outdoor HV porcelain product of steelmaking dust more, caused by creepage on the short circuit, the blackout caused great losses. And as low as 2 from the transformer room, due to the prolific dust area, dust accumulation in DZ type automatic air switch upper, makes the interphase insulation strength greatly reduced, resulting in short line bus accident, make the production discontinued for more than ten hours. There are dust collection on the terminal board, resulting in electrical misoperation, short circuit and so on, causing great harm to its safe operation.
3.2 cause bad electrical switch contact
When the dust collector is stored in the contact between the electric switch and the electromagnetic iron core, the utility model can cause the bad contact fault of the electric switch, especially in the control circuit of the electric contactor. The electric control system is unstable, and it is good or bad, so the phenomenon of the single phase operation contact adhesion often causes the accident of the equipment.
3.3 dust caused by poor ventilation
The cooling of the motor is driven by the exhaust of the air passage, the forced cooling of the fan and the casing