General Background on Electronic Equipment: The Interrelation of Circuit Design, Mechanical Design and Manufacturing

Lecture

An electrical apparatus – an electrical engineering device used for switching electrical circuits on and off,

for monitoring, measurement, protection, control and regulation of installations

intended for the transmission, conversion, distribution and consumption of electric power.

Electronic equipment — a collection of technical devices based on the use of electronic components and designed for processing, transmitting, storing and managing information. It covers a wide range of equipment — from household appliances to complex industrial systems.

Electronic equipment — electrical engineering devices whose operation is based on the use of electronic circuits, components and technologies. It is used to control electrical circuits, protect equipment, convert signals and perform computational operations.

Main Functions

Control: switching electrical circuits on and off, regulating parameters.
Protection: preventing fault conditions, protection against overloads and short circuits.
Monitoring and measurement: monitoring voltage, current, frequency, temperature.
Signal conversion: amplification, filtering, digital processing.
Automation: keeping systems running without constant human intervention.

The development of semiconductor technology and microprocessor devices has made it possible to expand the functional capabilities and scope of application of electrical apparatus and electronic devices.

Consequently, the term "electrical apparatus" is now understood to cover a broad range of devices used in the home,

in industry and in the power sector.

This textbook covers the fundamentals of the theory, design and operating characteristics of such apparatus

Classification

Electronic equipment is divided into several categories:

Category	Examples	Purpose
Switching	relays, contactors, switches	Switching circuits on/off
Protective	fuses, circuit breakers	Protection against fault conditions
Regulating	stabilizers, sensors	Maintaining grid parameters
Starting and regulating	starters, regulators	Control of electric motors
Information	computers, microcontrollers	Data processing and storage
Household	televisions, smartphones, audio systems	Everyday use

Electrical apparatus (EA) – electrical engineering devices used in the utilization of electric power, from its generation, transmission and distribution through to its consumption.

One of the main classification criteria for electrical apparatus is voltage. On this basis, a distinction is made between

low-voltage apparatus, up to 1000 V (LVA)
and high-voltage apparatus, above 1000 V (HVA).

Low-voltage apparatus is generally divided into the following main types:

Control and protection apparatus – automatic circuit breakers,

contactors, relays, electric motor starters, switches, knife switches, fuses, control buttons and other apparatus that govern the operating modes of equipment and its protection.

Automatic regulation apparatus – stabilizers and regulators of voltage, current, power and other electric power parameters.

Automation apparatus – relays, sensors, amplifiers, converters and other apparatus performing the functions of monitoring, amplification and conversion of electrical signals.

LVA is sometimes classified by the magnitude of switching current

into low-current (up to 10 A) and high-current (above 10 A) types. Here, the lower limits of switching currents in modern electrical apparatus (EA) reach 10-9 A, and of voltages – 10-5 V.

HVA, operating in networks with voltages of up to 1150 kV AC and 750 kV DC, also differ considerably in their functions. HVA generally includes the following main types of apparatus:

High-voltage circuit breakers – providing for the switching of electrical circuits on and off under various operating conditions,

including fault conditions, for example a short circuit (SC).

Reactors: current-limiting reactors – for limiting short-circuit currents, and shunt reactors – for limiting overvoltages and compensating reactive power.

Overvoltage limiters based on spark gaps and elements with a nonlinear current-voltage characteristic (for example, zinc oxide surge arresters – ZOSA).

Disconnectors and load-break switches – for de-energized disconnection of a circuit during repair of electrical equipment.

Instrument transformers – for connecting electrical measuring equipment in high-voltage circuits.

Most electromechanical EA are based on a contact system with various types of drives – manual, electromagnetic, mechanical, pneumatic, etc.

The processes occurring in EA are described by various and diverse physical phenomena studied in electrodynamics, mechanics, thermodynamics and other fundamental sciences.

The presence of moving mechanical parts, sparking and arcing phenomena during switching, limited speed of response and other negative factors inherent in electromechanical EA prompted work on developing static EA based on semiconductor elements. Earlier, in the scientific and technical literature, such EA were called contactless apparatus, and more recently – power electronic apparatus.

To prevent operating personnel from coming into contact with live or moving parts, and to prevent foreign objects from getting inside the EA, protective enclosures are fitted. According to GOST 14254-80, the protective properties of an enclosure are denoted by the letters IP followed by two digits. The first digit indicates the degree of protection against personnel contact with hazardous parts, and the second – the degree of protection against the ingress of foreign objects and liquids. For example:

IP 00 – open design.
IP 20 – protected design.
IP 60 – dust-protected design.
IP 65 – dust- and splash-protected design.
IP 66 – dust- and water-tight design.
IP 67 – hermetically sealed design.

The effects of mechanical and climatic factors on EA are governed by standards (GOST 15150-69 and GOST 15543-70).

Climatic environmental factors are understood to mean ambient air temperature and humidity; solar radiation; wind and dust, snow, etc.

Technical documentation always specifies the values of climatic factors within which normal operation of the product is ensured. These values are commonly called rated values.

Operating and limiting values of the factors are also distinguished. The values of climatic factors at which

the retention of rated parameters and the warranty service life are ensured are called operating values.

Values of climatic factors:

a) at which the apparatus's operability is retained (permissible deviations in accuracy and rated parameters are ensured);
b) after the cessation of which the accuracy and rated

parameters are restored are commonly called limiting operating values.

From the standpoint of the effects of climatic factors, the surface of the globe is divided into a number of macroclimatic regions, and the design of the EA is chosen depending on which of them it is intended to work in:

with a temperate climate;
with a temperate and cold climate;
with a humid tropical climate;
with a dry tropical climate;
with a dry and humid tropical climate.

Depending on their location, EA are divided into five categories:

outdoors;
under a canopy or in an open enclosure;
indoors, with natural ventilation;
indoors, with semi-natural ventilation and its own microclimate;
indoors, with elevated humidity.

When designing apparatus, its design version, placement category, maximum installation height above sea level, etc. must be taken into account.

Applications

Everyday life: televisions, smartphones, audio systems, household appliances.
Industry: automation systems, CNC machine tools, measuring instruments.
Power engineering: control of generators, transformers, distribution networks.
Medicine: diagnostic instruments, ultrasound machines, laser systems.
Science and education: laboratory equipment, computing systems.

THE INTERRELATION OF CIRCUIT DESIGN, MECHANICAL DESIGN AND MANUFACTURING.

Basic definitions
Technology is the science that studies the fundamental laws governing the production
process and uses them to obtain products of the required quality,
in the specified quantity and range, at minimum cost in materials,
energy and labor
Design is a set of elements and parts with different physical
properties and shapes, existing in a definite spatial,
mechanical, thermal, electromagnetic and energy relationship
This relationship is determined by the electrical circuit diagrams and the design
documentation, and it ensures that the electronic equipment
(REA) performs its specified functions with the required accuracy and reliability under the influence of
various factors (production-related, operational and other factors).
Production, as a technological system, is a set of interrelated
processes by which, from raw material resources and under the action of natural forces,
people create the necessary products by means of the means of production and
items of consumption.
The objects of production are examples of equipment and products of labor intended for
direct use in the sphere of consumption or production.
The development of modern production is characterized by dynamism
(a continuous process of renewing the material and technical base and the methods
of running production), by the increasing complexity of the production preparation cycle, and by
comprehensive mechanization and automation of production operations.
Production technology, or the technological process (TP), is the main part
of the production process, consisting in carrying out specified actions in accordance with
process documentation, aimed at changing the initial properties
of the object of production and bringing it to a defined state that conforms to
the design documentation.

Design and production technology, being separate parts of
the complex process of developing electronic equipment, cannot, under present-day conditions,
be carried out in isolation, without taking into account the relationships between each other and other
stages in the creation of new equipment. Being stages of the overall
"development – production – operation" process, design and development
ultimately determine the overall consumer properties of the electronic equipment.
The subject of this discipline is the study of the constituent parts of modern
production technology for electronic equipment