What factors affect the reliability of electrical equipment

Operating experience shows that the reliability of electrical equipment depends on numerous and different factors, which can be conditionally divided into four groups; constructive, production, installation, operational.

Design factors due to the installation of unreliable elements in the device; shortcomings of schemes and design decisions made during design; the use of components that do not meet the environmental conditions.

Production factors caused by violations of technological processes, pollution of the surrounding air, workplaces and devices, poor quality control of production and installation, etc.

During the installation of electrical devices, their reliability can be reduced if the technological requirements are not observed.

Operating conditions have the greatest influence on the reliability of electrical devices.Impact, vibration, overload, temperature, humidity, solar radiation, sand, dust, mold, corrosive liquids and gases, electric and magnetic fields affect the operation of devices.

Different operating conditions can affect the service life and reliability of electrical installations in different ways. Shock and vibration loads significantly reduce the reliability of electrical devices.

The impact of shock and vibration loads in some cases can be more significant than the impact of other mechanical as well as electrical and thermal loads. As a result of prolonged alternating action even under small shock-vibration loads, fatigue accumulates in the elements, which usually leads to sudden failures. Under the influence of vibrations and shocks, numerous mechanical damages occur to the structural elements, their fastenings are loosened and the contacts of the electrical connections are broken.

Loads in cyclic modes of operation associated with frequent switching on and off of an electrical device, as well as shock and vibration loads, contribute to the appearance and development of signs of element fatigue.

The physical nature of the increase in the risk of damage to devices when they are turned on and off is that during transient processes, overcurrent and overvoltage occur in their elements, the value of which often significantly exceeds (albeit briefly) the values ​​allowed by the technical conditions.

Electrical and mechanical overloads occur as a result of malfunctioning of the mechanisms, significant changes in the frequency or voltage of the power network, thickening of the lubricant of the mechanisms in cold weather, exceeding the nominal design temperature of the environment at certain times of the year and day, etc.

Overloads lead to an increase in the heating temperature of the insulation of electrical devices above the permissible level and a sharp decrease in its service life.

Climatic influences, especially temperature and humidity, affect the reliability and durability of any electrical device.

At low temperatures, the impact strength of the metal parts of electrical devices decreases: the values ​​of the technical parameters of the semiconductor elements change; there is "sticking" of the relay contacts; the tire is destroyed.

Freezing or thickening of lubricants makes switches, control knobs and other items difficult to operate. High temperatures also cause mechanical and electrical damage to the elements of an electrical device, accelerating its wear.

The effect of increased temperature on the reliability of the operation of electrical devices manifests itself in a wide variety of forms: cracks form in insulating materials, the insulation resistance decreases, which means that the risk of electrical damage increases, the tightness is broken (planting and impregnating joints begin to expire.

Damage to the windings of electromagnets, electric motors and transformers occurs as a result of insulation failure. Elevated temperature has a noticeable effect on the operation of the mechanical elements of electrical devices.

Under the influence of moisture, very rapid corrosion of metal parts of electrical devices occurs, the surface and volume resistance of insulating materials decreases, various leaks appear, the danger of surface destruction increases sharply, fungal mold forms, under the influence of which the surface of materials has corroded the electrical properties of the devices deteriorate.

Dust, getting into the lubricant, settles on the parts and mechanisms of electrical devices and causes rapid wear of the rubbing parts and contamination of the insulation. Dust is most dangerous for electric motors, where it falls with the intake air for ventilation. In other elements of electrical devices, however, wear is greatly accelerated if dust penetrates through the seals to the friction surface. Therefore, with a high dust content, the quality of the seals of the elements of electrical devices and their care are of particular importance.

The quality of operation of electrical devices depends on the degree of scientific validity of the working methods used and the qualification of the service personnel (knowledge of the material part, theory and practice of reliability, the ability to quickly detect and eliminate faults, etc.).

The use of preventive measures (routine maintenance, inspections, tests), repairs, use of experience in the operation of electrical devices guarantee their higher operational reliability.

See also: Measures to ensure the reliability of the operation of electrical devices