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Operating conditions (use), requirements for maintenance and repair

Lecture



Extensive use of radio-electronic devices in various environments of human activity is reflected in the design requirements for operating conditions. Depending on the type and purpose of the RES, in general, indicate: the operating conditions under which the use of the product with the specified technical indicators should be ensured; permissible climatic conditions (temperature, humidity, atmospheric pressure, solar radiation, corrosive media, dust, etc.); permissible impact of mechanical loads (vibration, shock, twisting, wind, etc.): the time of preparation of the product for use after transportation and storage: type of service (permanent or periodic) or the admissibility of work without maintenance; frequency and estimated complexity of maintenance and repair; The required number and qualification of personnel; the parameters of the product with which the product under development should function, as well as the requirements for ensuring the use of this product in the event of a failure of the product under development.

From a design point of view, the effects of climatic conditions and mechanical loads are extremely important. Climatic influences are characterized by the influence of temperature, thermal shock, humidity, atmospheric pressure, dust, solar radiation. This should take into account the content in the atmosphere of corrosive substances — sulfur dioxide, chloride and ammonia. For tropical operating conditions, biological factors are additionally taken into account — the influence of mold, insects and rodents.

During operation and (or) transportation, almost all types of radio electronic devices are subject to mechanical stress — vibrations, shocks, linear accelerations and acoustic shocks. Mechanical effects can cause large destructive stresses in the elements of radio electronic devices.

Vibrations are periodic oscillations that occur in the apparatus when in contact with a collar source (installation object, vehicle). Distinguish vibration resistance (functioning of the apparatus in terms of vibration) and vibration strength (opposition of the apparatus to the damaging effects of vibration in the idle state). The parameters of vibration exposure are frequency and acceleration specified in the TOR. A shock is characterized by a pulse duration and acceleration, and a linear acceleration by acceleration.

Acoustic noise occurs in the working engines of an installation facility (rockets, airplanes) and is characterized by sound pressure and a spectrum of sound frequencies.

Accounting for all factors influencing the RES in their design is extremely difficult, requires a large amount of experimental and research work. To simplify this issue, the execution of products suitable for work in different climatic areas, as well as the conditions of placement at the facility are systematized and standardized.

Table 6.1 The main climatic modification of products

Area code

Execution, climate

Have

Moderate

UHL

Temperate and cold

Tv

Wet tropical

Vehicle

Dry tropical

M

Moderately cold sea

Tm

Tropical sea

ABOUT

Climate for sushi

OM

All-Climate Marine

AT

All-climate performance for land and sea (does not apply to Antarctica)

Table 6.2 Location category of radio electronic facilities at the facilities

Category

Characteristic

one

Outdoors

1.1

for storage and work in category 4 premises and for short-term work in other conditions, including in the open air

2

Under a canopy and on objects where the rims of *** temperature and humidity are slightly different from the conditions of the open air

2.1

Inside product placement categories 1; 1.1; 2, but with the exclusion of the condition of moisture condensation

3

In closed rooms with natural ventilation without air conditioning

3.1

In irregularly heated rooms (objects)

four

In rooms (objects) with an artificial climate

4.1

When air conditioning or partial air conditioning

4.2

Inside industrial heated rooms

five

In rooms with high humidity. leading to frequent moisture condensation on walls and ceilings

5.1

Inside products of category 5. but subject to the exclusion of moisture condensation on this product

Depending on the operating conditions, domestic RES are divided into four groups. In accordance with these groups, the equipment must withstand the climatic and mechanical influences established in GOST 11478-83.

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Design and engineering of electronic equipment

Terms: Design and engineering of electronic equipment