Switches, switches, knife switches and starters. Scheme, description

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Electrician

Switches, switches, knife switches and starters. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Electrician's Handbook

Electromagnetic starters are called electrical devices that connect the load to the alternating current network.

They are used for remote control of electrical loads up to 75-80 kW. The load is controlled by direct connection of the load through the main contacts of the starter to the 220/380 V network. The control signal is applied to the starter coil and this leads to the closure of the main contacts.

The main load is electric motors.

In most cases, starters have maximum protection:

from overloads of unacceptable duration;
from currents of increased magnitude in the event of a break in one of the phases;
as well as minimum protection from a voltage drop in the network.

The essence of minimum protection: when the voltage in the supply network drops by 30-35% of the nominal value, the magnetic flux of the coil is not able to hold the moving part of the core and the main contacts open.

Attention! Protection against short circuit currents is not provided. To do this, high-speed fuses are installed in the power circuit in front of the magnetic starter.

Starters classified according to several criteria:

1) Rated voltage.
2) Rated current in amperes, the value of which indicates the size of the starter.
Zero value - 6,3 A at a main circuit voltage of 380 V.
The first value is 10 A at a main circuit voltage of 380 V.
The second value is 25 A at a main circuit voltage of 380 V.
The third value is 40 A at a main circuit voltage of 380 V.
The fourth value is 63 A at a main circuit voltage of 380 V.
The fifth value is -100 A at a main circuit voltage of 380 V.
The sixth value is 160 A at a main circuit voltage of 380 A.

Permissible current of the main contacts may differ from the above. It depends on the application category - AC.

AC-1 - the load is purely active or low inductive.
AC-3 - in the mode of direct start of an electric motor with a squirrel-cage rotor or turning off rotating motors.
AC-4 - start of an electric motor with a squirrel-cage rotor or shutdown of stationary and slowly rotating electric motors.

Consider the example. Starter of the 6th magnitude in the mode:

AC-1 - rated current 160 A;
AC-3 - rated current 150 A, at T=45 °C;
AC-3 - rated current 145 A, at T=50 °C;
AC-3 - rated current 140 A, at T=55 °C.

Also, the permissible current of the main contacts of the starter is reduced if it is used in circuits with a voltage of more than 380 V.

3) Protection class (IP).

The classification of domestic starters is as follows:

By the type of load switching circuit (electric motor) - reversible or non-reversible.
By the presence of a push-button post on the body of the starter.
By the presence of additional contacts.
By the presence of thermal relays.
According to the parameters of the signal applied to the coil (direct/alternating current and nominal voltage of the coil).

Widely used brands - PML, PME, PMA.

All the necessary parameters are indicated on the cases of imported starters (and more and more often on domestic ones recently). This allows during installation to check the conformity of the mounted starter for a particular circuit.

Author: Koryakin-Chernyak S.L.

See other articles Section Electrician's Handbook.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Traffic noise delays the growth of chicks 06.05.2024

The sounds that surround us in modern cities are becoming increasingly piercing. However, few people think about how this noise affects the animal world, especially such delicate creatures as chicks that have not yet hatched from their eggs. Recent research is shedding light on this issue, indicating serious consequences for their development and survival. Scientists have found that exposure of zebra diamondback chicks to traffic noise can cause serious disruption to their development. Experiments have shown that noise pollution can significantly delay their hatching, and those chicks that do emerge face a number of health-promoting problems. The researchers also found that the negative effects of noise pollution extend into the adult birds. Reduced chances of reproduction and decreased fertility indicate the long-term effects that traffic noise has on wildlife. The study results highlight the need ... >>

Wireless speaker Samsung Music Frame HW-LS60D 06.05.2024

In the world of modern audio technology, manufacturers strive not only for impeccable sound quality, but also for combining functionality with aesthetics. One of the latest innovative steps in this direction is the new Samsung Music Frame HW-LS60D wireless speaker system, presented at the 2024 World of Samsung event. The Samsung HW-LS60D is more than just a speaker system, it's the art of frame-style sound. The combination of a 6-speaker system with Dolby Atmos support and a stylish photo frame design makes this product the perfect addition to any interior. The new Samsung Music Frame features advanced technologies including Adaptive Audio that delivers clear dialogue at any volume level, and automatic room optimization for rich audio reproduction. With support for Spotify, Tidal Hi-Fi and Bluetooth 5.2 connections, as well as smart assistant integration, this speaker is ready to satisfy your ... >>

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Random news from the Archive

More and more hard drives are being bought 11.10.2012

A year ago, the hard disk drive industry was hit hard by a Thai flood, which drastically reduced the supply of the product. Various sources gave different estimates of the timing of the recovery of the industry. Now you can forget about forecasts on this score - according to IHS iSuppli analysts, the industry has already fully recovered, and this year's shipments will be a record in history.

The total volume of HDD deliveries in 2012 will amount to 524,0 million units, which is 4,3% more than last year's figure of 502,5 million units. Growth engines named the corporate segment and the expected release of Windows 8.

Interestingly, the growth rate will continue in the coming years, at least until 2016. By that time, the market will increase to 575,1 million units, analysts believe.

The forecast includes only HDDs used in computers - desktop and mobile PCs, servers and storages. But it doesn't take into account HDDs intended for applications such as, say, car in-vehicle systems, video recorders, or external drives. Incidentally, unlike the PC HDD market, shipments of HDDs for consumer electronics will decline this year compared to last year.

Other interesting news:

▪ New material changes shape

▪ Hydrogen from nuts

▪ Temperature and synthesis of pure polymers

▪ New family of USB microcontrollers on M8

▪ Underwater typhoons

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Personal transport: land, water, air. Article selection

▪ article This mystery is great. Popular expression

▪ article Which producer publicly asked viewers not to watch his newly made film? Detailed answer

▪ article Orthosiphon staminate. Legends, cultivation, methods of application

▪ article Photo of a relay that switches the load from lighting, 10-12 volts 120 watts. Encyclopedia of radio electronics and electrical engineering

▪ article The cube went through the glass. Focus Secret

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews