Classification of electrical appliances

Electrical appliances This is a device that controls electrical consumers and supplies, and also uses electrical energy to control non-electrical processes.

Electrical devices for general industrial purposes, electrical household appliances and devices are produced with a voltage up to 1 kV, high voltage — above 1 kV. Up to 1 kV are divided into manual and remote control devices, protective devices and sensors.

Electrical devices are classified according to a number of characteristics:

1. by purpose, i.e. the main function performed by the device,

2. regarding the principle of action,

3. by the nature of the work

4. type of current

5. the magnitude of the current

6. voltage value (up to 1 kV and more)

7. performance

8. degrees of protection (IP)

9. by design

Features and areas of application of electrical devices

Classification of electrical devices depending on the purpose:

1.Control devices intended for starting, reversing, stopping, regulating the speed of rotation, voltage, current of electric machines, metal cutting machines, mechanisms or for starting and regulating the parameters of other consumers of electricity in power supply systems. The main function of these devices is to control electric drives and other consumers of electrical energy. Features: frequent switching on, switching off up to 3600 times per hour, i.e. 1 time per second.

These include electrical hand control devices — packet switches and switches, knife keys, universal keys, controllers and commanders, rheostats, etc., and electrical remote control devices — electromagnetic relays, appetizers, contactors etc.

2. Protective devices are used to switch electrical circuits, protect electrical equipment and electrical networks from overcurrent, i.e. overload currents, peak currents, short-circuit currents.

They include fuses, thermal relays, current relays, circuit breakers etc.

3. Control devices are designed to control certain electrical or non-electrical parameters. This group includes sensors. These devices convert electrical or non-electrical quantities into electrical ones and provide information in the form of electrical signals. The main function of these devices is to control the specified electrical and non-electrical parameters.

These include sensors for current, pressure, temperature, position, level, photo sensors, as well as relays that perform sensing functions, for example speed control relay (RKS), time relay, voltage, current.

Classification of electrical devices according to the principle of operation

According to the principle of operation, electrical devices are divided depending on the nature of the impulse acting on them. Based on the physical phenomena on which the operation of the devices is based, the following categories are the most common:

1. Electrical switching devices for closing and opening electrical circuits using interconnected contacts to ensure the passage of current from one contact to another or distant from each other to break the electrical circuit (keys, switches, … )

2. Electromagnetic electrical devices, the action of which depends on the electromagnetic forces arising during the operation of the device (contactors, relays, ...).

3. Electric induction device, the action of which is based on the interaction of current and magnetic field (induction relays).

4. Inductors (reactors, chokes for saturation).

Classification of electrical devices according to the nature of work

By the nature of work, electrical devices are distinguished depending on the mode of the circuit in which they are installed:

1. Devices that work for a long time

2. intended for short-term operation,

3. work under intermittent load conditions.

Classification of electrical devices according to the type of current

By the nature of the current: direct and alternating.

Requirements for electrical appliances

Design varieties of modern devices are particularly diverse, in this regard, the requirements for them are also different. However, there are some general requirements regardless of the purpose, application or design of the apparatus.They depend on the purpose, operating conditions and required reliability of the devices.

The insulation of the electrical device must be calculated depending on the conditions of possible overvoltages that may occur during the operation of the electrical installation.

Devices intended for frequent switching on and off of the rated load current must have high mechanical and electrical durability, and the temperature of the current-carrying elements must not exceed the permissible values.

In the event of a short circuit, the current-carrying part of the device is subjected to significant thermal and dynamic loads, which are caused by a large current. These extreme loads must not interfere with the continued normal operation of the apparatus.

Electrical devices in the circuits of modern electrical devices must have high sensitivity, speed, flexibility.

A general requirement for all types of devices is the simplicity of their construction and maintenance, as well as their efficiency (small dimensions, the lowest weight of the device, the minimum amount of expensive materials for the production of individual parts).

Operating modes of electrical devices

The nominal mode of operation is a mode in which an element of an electrical circuit operates at the values ​​of current, voltage, power specified in the technical passport, which corresponds to the most favorable operating conditions in terms of efficiency and reliability (durability).

Normal operation — a mode when the device operates with mode parameters slightly different from the nominal ones.

Emergency operation — this is a mode when the parameters of current, voltage, power exceed the nominal two or more times.In this case, the object should be disabled. Emergency modes include passing short-circuit currents, overload currents, undervoltage in the network.

Reliability - trouble-free operation of the device for the entire period of its operation.

The property of an electrical device to perform certain functions, maintaining in time the values ​​of the established operational indicators within the specified limits, corresponding to the specified modes and conditions of use, maintenance and repair, storage and transportation.

Execution of electrical devices according to the degree of protection

Degree of protection against penetration of solid particles and liquids determined by GOST 14254-80. In accordance with GOST, 7 degrees from 0 to 6 of the penetration of solid particles and from 0 to 8 of the penetration of liquid are established.

Determination of degrees of protection

Protection against ingress of solids and personnel contact with live and rotating parts.

Protection against water penetration.

0

There is no special protection.

1

Large areas of the human body, such as hands and solid particles larger than 50 mm.

Drops falling vertically.

2

Fingers or objects no longer than 80mm and solid bodies over 12mm long.

Drops when the shell is tilted up to 150 in any direction from the normal position.

3

Tools, wires and solid particles with a diameter of more than 2.5 mm.

Rain falling on the shell at an angle of 600 from the vertical.

4

Wire, solid particles larger than 1 mm.

Splashes falling on the shell in every direction.

5

Insufficient amount of dust to interfere with product performance.

Ejected jets in every direction.

6

Full protection from dust (dust proof).

Waves (water should not enter during waves).

7

—

When immersed in water for a short time.

8

—

With prolonged immersion in water.

The abbreviation «IP» is used to indicate the degree of protection. For example: IP54.

As for electrical devices, there are the following types of implementation:

1. Protected IP21, IP22 (not lower).

2. Splash proof, drip proof IP23, IP24

3. Waterproof IP55, IP56

4. Dustproof IP65, IP66

5. Enclosed IP44 — IP54, these devices have an internal space isolated from the external environment

6. Sealed IP67, IP68. These devices are made with particularly dense insulation from the environment.

Climatic characteristics of electrical appliances determined by GOST 15150-69. In accordance with the climatic conditions, it is designated by the following letters: У (N) — temperate climate, CL (NF) — cold climate, TB (TH) — tropical humid climate, ТС (TA) — tropical dry climate, О ( U) — all climatic regions, on land, rivers and lakes, M — temperate maritime climate, OM — all marine zones, B — all macroclimatic regions on land and in the sea.

Categories placement of electrical devices:

1. Outdoors,

2. Rooms in which fluctuations in temperature and humidity do not differ significantly from fluctuations in the open air,

3. Closed premises with natural ventilation without artificial regulation of climatic conditions. No exposure to sand and dust, sun and water (rain),

4. Room with artificial regulation of climatic conditions. No exposure to sand and dust, sun and water (rain), outside air,

5. Rooms with high humidity (prolonged presence of water or condensed moisture)

The climatic version and the placement category are entered in the type designation of the electrical product.

Selection of electrical devices

The choice of electrical devices is a problem, in the solution of which the following should be considered:

• electrical apparatus, switched currents, voltages and powers;
• parameters and nature of the load — active, inductive, capacitive, low or high resistance, etc.;
• the number of circuits involved;
• voltages and currents of control circuits;
• voltage windings of electrical apparatus;
• operating mode of the device - short-term, long-term, multiple-short-term;
• operating conditions of the device — temperature, humidity, pressure, vibrations, etc.;
• methods of fixing the device;
• economic and weight and size indicators;
• ease of pairing and electromagnetic compatibility with other devices and devices;
• resistance to electrical, mechanical and thermal overloads;
• climate modification and placement category;
• Degree of IP protection,
• safety requirements;
• height above sea level;
• Terms of Use.