BA series circuit breakers are designed for alternating current circuits with a frequency of 50/60 Hz with rated voltages up to 690V and rated currents up to 6300A. The VA switch is used in power plants, factories, mines and other large facilities in power distribution circuits and protection circuits for electrical circuits and power sources from long-term overloads and short circuit currents, from an unacceptable decrease in supply voltage, single-phase ground fault, as well as for prompt switching and disconnecting sections of electrical circuits. Depending on the type of circuits, operating conditions and type of load, VA circuit breakers are manufactured for different rated currents and types of protective characteristics.

The VA circuit breaker is equipped with a microcontroller that provides precise programmable selective protection, which ensures high reliability of circuit protection and avoids nuisance tripping. The basic installation option is stationary. A roll-out version is available complete with mounting socket and trolley.

Automatic switches VA 47-29, VA 47-100 Automatic switches BA 47-29 and VA 47-100 are designed to protect electrical circuits from overloads and short circuit currents, as well as to implement operational control of sections of electrical circuits. Switches are produced with protective characteristics B, C, D (VA 47-100 only C, D). During overloads in the protected circuit, the flowing current heats the bimetallic plate. When heated, the plate bends and acts on the free release lever. When there is a short circuit in the protected circuit, the current flowing through the electromagnet coil of the circuit breaker increases many times, and accordingly, a magnetic field appears that moves the core, acting on the free tripping lever. In both cases, the moving contact is separated from the stationary one, the machine turns off, the circuit breaks, thereby protecting the electrical circuit from overloads and short circuit currents. The machines have two overcurrent protection systems: electrothermal and electromagnetic, with mutually agreed upon characteristics. Available in one-, two-, three- and four-pole versions; Installation of circuit breakers is carried out on a 35 mm mounting DIN rail. Wide operating temperature range from -400 C to +500 C.

Automatic switches VA 50-41, VA 50-43 Automatic switches VA 50-41, VA 50-43 are designed to conduct current in normal mode and cut off the current in case of short circuits, overloads and unacceptable low voltages, as well as for infrequent operational switching on and off of electrical circuits and are designed for operation in electrical installations at rated voltage up to 440 V DC and voltage up to 660 V AC at 50 and 60 Hz. The switches operate normally at altitudes up to 4300 meters above sea level; above 2000 meters the rated current is reduced by 20%. It is allowed to operate switches at an ambient temperature of 55°C. Fixed-type switches allow front and rear connection to the main circuit terminals, while withdrawable-type switches allow only rear connection. The operating position of stationary switches in space is on a vertical plane with the terminals of the fixed contacts upward. A deviation of up to 90° in any direction in the specified plane and up to 5° in any direction from the specified plane is allowed. The operating position of switches with a retractable device in space is on a vertical plane with the terminals of the fixed contacts up, with the possibility of rotating from this position in the indicated plane 90° to the left at the rated currents of the releases 250; 400; 630 A.

Automatic switches VA 57-31 Automatic switches are designed to conduct electric current in normal mode and cut off the current in case of overloads, short circuits and unacceptable voltage drops, as well as up to 30 operational switching on and off of electrical circuits per day. Switches 57-31 comply with GOST standards: Application category – A (according to GOST R 50030.2); Switches of the BA 57-31 series are designed for currents of 16-100 A. Operation in electrical installations with a rated operating voltage of up to 660 volts, alternating current with a frequency of 50 and 60 Hz and up to 220 V direct current is allowed.

Automatic switches VA57-35, VA57F-35 Automatic switches are designed to conduct electric current in normal mode and cut off the current in case of overloads, short circuits and unacceptable voltage drops, as well as up to 30 operational switching on and off of electrical circuits per day. Switches VA57-35, VA57F-35 comply with GOST standards: Application category – A (according to GOST R 50030.2); Mechanical design group – M3 (according to GOST 17516.1); Atmosphere type II (according to GOST 15150); Types of climatic versions of switches UHL3 and T3 (according to GOST 15150) Switches of the VA57-35, VA57F-35 series are designed for currents of 16-250 A. Operation in electrical installations with a rated operating voltage of up to 660 volts, alternating current with a frequency of 50 and 60 Hz and up to 220 V direct current is allowed.

Automatic switches are designed to conduct electric current in normal mode and cut off the current in case of overloads, short circuits and unacceptable voltage drops, as well as up to 30 operational switching on and off of electrical circuits per day. VA57-39 switches comply with GOST standards: Application category – A (according to GOST R 50030.2); Mechanical design group – M3 (according to GOST 17516.1); Atmosphere type II (according to GOST 15150); Types of climatic versions of switches UHL3 and T3 (according to GOST 15150) Switches of the BA57-39 series are designed for currents of 320-630 A. Operation in electrical installations with a rated operating voltage of up to 660 volts, alternating current with a frequency of 50 and 60 Hz and up to 220 V direct current is allowed.

Automatic switches are designed to conduct electric current in normal mode and cut off the current in case of overloads, short circuits and unacceptable voltage drops, as well as up to 30 operational switching on and off of electrical circuits per day. Modular circuit breakers BA 61-29, for currents 0.5-63 A are available in: Switches of the BA61-29 series are designed for currents of 0.5-63 A. Modular circuit breakers of the BA61-29 series are designed for operation in alternating current networks with a voltage of 220/380 V, frequency 50 Hz, and direct current with a voltage of 60/110 V. The switches are operated in electrical installations for industrial and domestic use and comply with the requirements: GOST 50030.3

Automatic switches BA61E-29 Automatic switches are designed to conduct electric current in normal mode and cut off the current in case of overloads, short circuits and unacceptable voltage drops, as well as up to 30 operational switching on and off of electrical circuits per day. Modular circuit breakers BA 61E-29, for currents 16-100 A are available in: type B, C, D (for domestic use); type Z, L, K (for industrial use) Switches with RCD-DM comply with the requirements of fire safety standards NPB-243-97. BA61F29+UZO-DM circuit breakers with a leakage current release disconnect the voltage from the consumer if the current in the protected pole differs from the current in the neutral pole by an amount greater than the setting. Setting 100, 300 mA - protection against fire in the event of violation of the insulation of networks of industrial and domestic buildings. Switches of the BA61E-29 series are designed for currents of 16-100 A. Modular circuit breakers of the BA61E-29 series are designed for operation in alternating current networks with a voltage of 220/380 V, frequency 50 Hz, and direct current with a voltage of 60/110 V. The switches are used in electrical installations industrial and domestic use and meet the requirements: GOST 50030.3

Automatic switches VA67-31, VA67-33, VA67-35, VA67-37, VA67-39, VA 67-3(11) Automatic switches of the BA67 series are designed to conduct current in normal mode and cut off the current in case of short circuits, overloads, unacceptable voltage drops, as well as rare operational switching on and off of electrical circuits and are designed for operation in electrical installations with a rated voltage of up to 660 V AC with a frequency of 50 Hz with rated currents from 10 A to 800 A. Automatic switches are manufactured in accordance with IEC 60947-2 (GOST R 50030.2-99) Scope of application: protection of distribution networks, protection of electric motors. According to the method of protection against electric shock, VA67 automatic switches correspond to class 0 according to GOST 12.2.007.0-75 and must be installed in distribution equipment with protection class not lower than I. The degree of protection of distribution equipment from access to hazardous parts, ingress of external solid objects and water must be at least IP 30 according to GOST 14254-96.

Structure of the symbol for switches:

VA XX - XX - XX XX X X - XX XX
VA - Designation of the type of device
XX - Series designation: 04, 06
XX - Symbol of rated current: 36
XX - Symbol for the number of poles and the number of overcurrent releases in combination with the design of overcurrent releases for the protection zone:
- 3 poles with releases in the zone of short circuit currents – 33;
- 3 poles with releases in the zone of overload and short circuit currents – 34;
- 2 poles with releases in the zone of short circuit currents – 83;
- 2 poles with releases in the zone of overload and short circuit currents – 84.
XX - Designation of execution for additional assembly units:
- without additional assembly units – 00;
- with free contacts – 11;
- with free contacts and independent release – 18.
X - Designation of the design according to the type of drive and method of installation of the switch:
- stationary with manual drive – 1;
- stationary with electromagnetic drive – 3;
- retractable with manual remote drive – 5;
- retractable with electromagnetic drive – 7;
- cutter with manual drive – 2;
- cutter with electromagnetic drive – 9.
X - Designation for additional mechanisms:
- absent – ​​0;
- manual remote drive; for operating through the switchgear door – 5.
XX - Symbol of the degree of protection of the circuit breaker:
- IP20 - 20
- IP00 - 20
XX - Symbol of climatic version: UHL3, TZ

Circuit breakers of the BA51 and BA52 series have rated currents of 250, 400 and 630 A and are designed for operation in electrical installations with voltages up to 660 V AC and up to 440 V DC. The two-digit number 35, 37 or 39 following the series number means the rated current of the circuit breaker is 250, 400 or 630 A, respectively.

Switches provide protection against short-circuit currents, overloads and unacceptable voltage drops, as well as infrequent operational switching on and off of electrical circuits. They have electrothermal and electromagnetic current releases, but can only be designed with an electromagnetic release.

The rated currents of thermal releases have the following values: 100, 125, 160, 200, 250 A - for AB BA51 (52)-35; 250, 320, 400 A - for switches of the BA51 (52)-37 series; 400, 500, 630 A - for BA51-39 switches, 250, 320, 400, 500, 630 A - for BA52-39 series switches.

The ratio of the operating current of electromagnetic releases to the rated current of thermal releases (cut-off factor) is in the range of 10 - 12. The specified factor (cut-off factor) applies to AC circuit breakers. Automatic circuit breakers with thermal overload releases must operate at a current value equal to 1.25 of the rated current of the release for a time of less than 2 hours (in a heated state).

In Fig. 1. shows the protective characteristics of circuit breakers of the BA51(52)-35 series

Rice. 1. Protective characteristics of circuit breakers of the BA51(52)-35 series: zones of characteristics from the cold (1) and heated (2) states, zones of operation of the electromagnetic maximum release at direct (3) and alternating (4) currents.

VA53(55)-37 circuit breakers have rated currents of 160, 250, 400 A; switches BA53(55)-39 - 160, 250, 400, 630 A. The purpose and operating conditions are the same as for the switches BA51, BA52 described above.

Circuit breakers of the BA53 series are current-limiting, the BA55 series are selective with a time delay in the short-circuit current zone. The switches have a semiconductor overcurrent release and allow stepwise adjustment of the following parameters:

rated current of the release: 0.63; 0.8; 1.0 rated current of the circuit breaker. For example, for a circuit breaker with a rated current of 160 A, the rated current of the release during regulation can be set to 100, 125 and 160 A;

settings for operation current in the zone of short-circuit currents, a multiple of the rated current of the release: 2, 3, 5, 7 and 10 - for alternating current; 2, 4 and 6 - for direct current;

operating time settings in the short-circuit current zone for BA55 series circuit breakers: 0.1; 0.2 and 0.3 s - for alternating current; 0.1 and 0.2 s - for direct current.

Time settings operate in the selectivity zone, which is limited by the short-circuit current value of 20 - 28 kA, depending on the specific type of circuit breaker. Above the selectivity zone limit, the switches operate without a time delay.

The tripping current in the overload zone (trip current) is equal to 1.25 of the rated current of the release for all circuit breakers.

BA75-45 series circuit breakers have one rated release current - 2500 A; VA75-47 have a maximum release with a rated current of 2500 or 4000 A. The specified values ​​of the rated currents of the releases are also considered the rated currents of the circuit breakers. The protective characteristics of the switches are shown in Fig. 2.

Rice. 2. Protective characteristics of circuit breakers of the BA75-45(47) series of direct (a) and alternating (b) current: with releases of 1600, 2000, 2500 A and settings in overload current zones of 4, 8, 16 s, and short-circuit current zones - 0.1 and 0.2 s

The switches are designed for installation in electrical circuits with a rated voltage of alternating current up to 660 V and direct current up to 440 V and serve to protect electrical installations during overloads and short circuits, as well as for infrequent switching on and off of electrical circuits under rated operating conditions.

The switches have a semiconductor overcurrent release and allow stepwise adjustment of the following parameters:

rated current of the release: 0.63; 0.8; 1.0 rated current of the circuit breaker;

trip current settings in the short-circuit current zone are multiples of the rated current of the release: 2, 3, 5, 7 - for AC circuit breakers with a 2500 A release; 2, 3, 5 - for AC circuit breakers with a 4000 A release; 2, 4, 6 - for DC switches with a 2500 A release and 2, 4 - for DC switches with a 4000 A release;

response time settings in the overload current zone of 4, 8 and 16 s (at six times alternating and five times direct current);

response time settings in the short-circuit current zone (up to the upper limit of the selectivity zone) 0.1; 0.2; 0.3 s - for AC switches and 0.1; 0.2 s - for DC switches.

The selectivity zone is limited to values ​​of 36 and 45 kA (rms value) for AC circuit breakers with 2500 and 4000 A releases, respectively, and to values ​​of 50 and 60 kA for DC circuit breakers BA75-45 and VA75-47, respectively.

Automatic switches VA 21-29

BA 21 series circuit breakers are designed to protect electrical circuits from overloads and short circuits, promptly turn on and off these circuits (including asynchronous motors) and conduct current in the rated mode. Switches are manufactured in three types: VA 21-29 - with medium breaking capacity; VA 21-29V - with increased breaking capacity; VA 21-29T - for urban transport (single-pole in three-pole dimensions).

Main technical characteristics of automatic circuit breakers VA 21-29

Three-pole circuit breakers BA51 and BA52

Automatic switches of the BA51, BA52 type are designed to conduct current in normal mode and cut off the current in case of short circuits, overloads and unacceptable voltage drops, as well as for infrequent (up to 6 per day) operational switching on and off of electrical circuits. It is allowed to use switches for infrequent direct starts and protection of asynchronous electric motors.

Symbol structure:

Switch Series:
VA51— switches with average switching capacity;
VA52— switches with increased switching capacity

Rated current:
35 — 250 A;
37 - 400 A;
39 — 630 A;

Number of poles and number of overcurrent releases:
3 — 3 poles with overcurrent releases in each pole;
8 — 2 poles with overcurrent releases in two poles in a 3-pole design of the circuit breaker;

Design of overcurrent releases according to the protection zone:
3 — release in the zone of short circuit currents;
4 - release in areas of short circuit and overload currents

Versions for additional assembly units

Type of drive and method of installation of the switch:
1 — manual drive, stationary version;
3 — electromagnetic drive, stationary version;
5 — manual remote drive, retractable version;
7 — electromagnetic drive, withdrawable version

Execution by additional mechanisms:
- absent;
5 — manual remote drive for operating a stationary circuit breaker with a manual drive through the door of the switchgear;
6 — a device for blocking the “Off” position of a stationary circuit breaker with a manual drive;

Switch protection degree according to GOST 14255-89: IP20, IP00

Basic technical data of circuit breakers:

Rated current of the circuit breaker, A

Rated currents of thermal overload releases, A

80, 100, 125, 160, 200, 250

250, 320, 400, 500, 630

Rated voltage of the main circuit, V:

AC frequency 50 and 60 Hz

Settings for the operation current of the electromagnetic overcurrent release in the short-circuit current zone, multiples of the rated current of the thermal overcurrent release:

at alternating current

(250, 320, 400A) 10

(250, 320A) 12;
(500, 630A) 10

at constant current

(80A) 10;
(100, 125A) 8;
(160, 200, 250A) 6

Automatic switches VA 04-36

The VA04-36 automatic machine is designed for switching electrical circuits and automatically opening during short circuits and overloads, as well as for manual switching on and off.
Switches can be manufactured in the following designs.
-Stationary version, retractable, plug-in,
-Climatic version UHL3, T.
-With electromagnetic and thermal releases
Complete set of circuit breakers BA 04-36.
When ordered, switches can be equipped with the following equipment
An independent release is a device that allows you to remotely turn off the circuit breaker when voltage is applied. The voltage of independent releases can be of the following ratings.
110V, 127V, 220V, 240V, 380V, 400V, 415V, 550V, 660V AC 50Hz;
115V, 220V, 230V, 380V, 400V, 415V, 440 V AC with a frequency of 50-60 Hz;
24V, 110V, 220V DC.
Minimum voltage release - a device that turns off the circuit breaker when the threshold voltage drops.
Electromagnetic drive is a device that allows you to remotely turn on a circuit breaker when voltage is applied to the contacts of the electric drive; the electromagnetic drive can have the following ratings
110V, 127V, 220V, 230V, 240V, 380V, 400V, 415V, 550V, 660V single-phase alternating current with a frequency of 50 Hz; 220V, 380V, 400V, 440V with a frequency of 60 Hz;
110V, 220V DC.

Automatic switches VA 47-63, VA 47-100, VA 47+N

Automatic circuit breakers VA 47-63, VA 47-100, VA 47+N are a modern generation of switching devices designed to protect circuits, as well as wires and cables from short-circuit currents and long-term overloads.
Switches are produced in single-pole, pole+neutral, two-, three- and four-pole versions.
It is possible to use a switch to quickly turn the network on and off.
The possibility of sealing is provided to prevent unauthorized access to the conductors.

1. Housing made of heat-resistant ABC - non-flammable plastic
2.Control handle
3.Contact position indicator “ON/OFF”
4.Knurled clamps for fixing external conductors
6.Electromagnetic release coil
7. Arc chamber
8. Mounting for 35mm DIN rail
9.Bimetallic plate

Automatic switches series VA-63

VA-63 circuit breakers are a modern generation of domestic switching devices of the highest quality and reliability, designed for operational control of sections of electrical circuits, as well as protection against overloads and short circuits.
Characteristics of circuit breakers: in EKF VA-63 circuit breakers, combined circuit protection is implemented: thermal (bimetallic plate) and electromagnetic (electromagnet).
The arcing chamber of the switches consists of 13 plates, which increases the switching wear resistance and gives high values ​​of the ultimate switching capacity. VA-63 have one-, two-, three- and four-pole versions and are produced with a type C response characteristic. For reliable connection of conductors, clamps made of anodized steel with notches are provided.
In terms of their technical characteristics, response time and breaking capacity, automatic switches of the VA-63 series are comparable to switches from the world's most famous manufacturers of low-voltage equipment.

1. Housing made of heat-resistant plastic
2.Control handle
3.Contact position indicator “ON/OFF”
4.Knurled clamps for external connection
5. Contacts with increased wear resistance
6.Electromagnetic splitter coil
7. Arc chamber
8.Adjustment screw

Operating principle of VA-63 circuit breakers
The main part of the circuit breaker is the thermal and electromagnetic releases. An electromagnetic release is an electromagnet coil connected in series to a controlled circuit, and a thermal release is a bimetallic plate that bends under the influence of overload currents. When switched on, the tripping springs in the switch are charged, and conditions are created for automatic shutdown when an emergency mode occurs.
When the current reaches the trip settings, the releases develop a force sufficient to bring the free release mechanism into an unstable state at the place where the switch latch. The force required to knock down the latch depends on the material and design of the latch assembly, the latch elements, the presence and condition of the lubricant, the coefficient of friction, etc. This explains the spread of response parameters in the short-circuit current zone (protective characteristics B, C and D and for modular circuit breakers Israb = I set + 20%).
In the event of an emergency shutdown, the free release mechanism disconnects the control handle from the contact system to prevent the circuit breaker from being re-closed.
To bring the VA-63 into working condition, it is necessary to check the circuit breaker, namely, so that the position of the cocking handle is in the lowest position.
The main advantages of VA-63 circuit breakers
Contacts with increased wear resistance;
Limit switching capacity 10 kA;
The number of plates in the arc-extinguishing chamber has been increased to 13;
A channel is provided for the removal of gases;
The main contacts are made of oxygen-free copper;
The body is made of flame retardant plastic;
Availability of contact position indicator;
Possibility of connection via comb bus;
The warranty on manufactured equipment is 5 years; The service life of the circuit breaker is more than 20 years.

A.2. General information about BA series circuit breakers

When operating electrical networks, long-term overloads of wires and cables and short circuits cause an increase in the temperature of the current-carrying conductors above the permissible limit.

This leads to premature wear of their insulation, which can result in a fire, explosion in hazardous areas, or injury to personnel.

To prevent this, the ESN line has a protection device that disconnects the damaged section.

Protection devices are: circuit breakers, fuses with fuse links and thermal relays built into magnetic starters.

Circuit breakers are the most advanced protection devices, reliable, triggered by overloads and short circuits in the protected line.

The sensitive elements of the machines are releases: thermal, electromagnetic and semiconductor.

Thermal releases are triggered during overloads, electromagnetic releases - during a short circuit, semiconductor releases - both during overloads and during a short circuit.

The most modern circuit breakers of the BA series are designed to replace the outdated A37, AE, AVM and Electron.

They have reduced dimensions, perfect structural components and elements. They work in DC and AC networks. Table A.6 provides VA data, since they are the most modern and are used in complete switchgears in the form of various combinations (PR 85, PR 87).

BA series circuit breakers

Switches of the VA series of developments 51, 52, 53, 55 are intended for shutdowns during short circuits and overloads in electrical networks, shutdowns during unacceptable voltage drops, as well as for infrequent operational switching on and off of electrical circuits.

BA series switches of developments 51 and 52 have thermal (TR) and electromagnetic releases, sometimes only EMR.

BA 51 have average switching capacity.

VA 52 - increased.

VA 51G and VA 52G are designed to protect motors with a short-circuit rotor operating in ASZ mode (start-up and shutdown).„

The response setting in the overload zone for a time of no more than 2 hours (with heating

They have 2- and 3-pole versions for voltages up to 660 AC and up to 400 V
standing current. . |

In A 51-31-1 they are used only for op-amps and have a 1-pole design.

BA series circuit breakers of developments 53, 55, 75 have a semiconductor maximum release with step control:

* rated current of the release: 0.63; 0.8; 1.0 from the rated current of the circuit breaker.
For example, at = 160 A you can set = 100, 125, 160 A;

* response settings in the short circuit zone for alternating current - (2, 3, 5, 7, 10) for direct current
yanny - (2, 4, 6)

* response time settings at 6 alternating and 5 direct current - 4.8
and 16 s.

VA 53 - current-limiting, VA 55 - selective with time delay in the short-circuit zone: 0.1; 0.2; 0.3 s - for variable and 0.1; 0.2 s - for direct current.

BPR - semiconductor release unit. Selectivity is ensured at short-circuit currents up to 20...28 kA, depending on the specific type of switch.

At high short-circuit currents, the switches operate instantly (without a time delay).

The tripping current in the overload zone is equal for all circuit breakers. Maximum

values ​​are selected if large current surges are possible in the protected area due to the technological process, the switching on of transformers or the start-up of electric motors.

If the load is quiet, you should choose no more than and in the absence of current surges. If necessary, the cutoff ratio can be increased in

The setting for the response time in the overload zone of more than 4 s should be taken under difficult conditions for starting the motor (high multiplicity of the starting current, significant moment of inertia of the mechanism) or during long peaks of the technological overload current.

According to the conditions of detuning from inrush currents (or load peaks), it is desirable that the current and response time exceed the calculated values ​​by at least 1.5 times.

According to the conditions of selectivity, the switch that is closer to the power source must have an operating time of at least 1.5 times longer (at the same current) than the operating time of the switch below the underlying stage.

VA 56 switches do not have maximum releases, but have main contacts with electrodynamic compensators, which have thermal and electrodynamic resistance. Despite the absence of releases at high values ​​of short-circuit current, they are automatically turned off.

Table A.5. Calculation dependencies for the selection of protection devices

In LV power networks

Notes

- maximum rated current in the line, A;

- cut-off current, A;

- starting current ED, A, - multiplicity of starting current, in the absence of data it is accepted = 6,5;

- peak current, A. This is the highest current occurring in the line, lasting 1...2 s;

(in the group more than 5 ED); (in the group up to 5 ED inclusive);

- maximum rated current in the group, A;

- starting and rated currents of the largest electric motor in the group, A;

- the coefficient taking into account the starting conditions is accepted: = 1.6. 2 (for severe
start, duration > 2.5 s), = 2.5 (with easy start, duration

VA circuit breakers designed for use in mines, factories, power plants, or other large facilities. They are used in circuit protection circuits, power distribution circuits, and power supplies. Protects against short circuit currents, long-term overloads, single-phase ground faults, and reduced supply voltage. They are also used to urgently turn off or turn on certain sections of electrical circuits.

Automatic switches of the VA series are used in alternating current circuits, where the rated voltage does not exceed 690 V, the frequency is 50/60 Hz, and the rated current does not exceed 6300 A. They are produced for various types of protective characteristics and rated currents. This depends on the operating conditions, type of circuits and type of load.

One of the features of the VA circuit breaker is the presence of a microcontroller. It helps provide programmable, precise, selective security. This greatly increases the reliability of protection for the circuits and eliminates false shutdowns.

Automatic switches are divided into:

Installation circuit breakers have a protective insulating (plastic) casing and can be installed in publicly accessible places;
- universal - do not have such a housing and are intended for installation in switchgears;
- fast-acting (their own response time does not exceed 5 ms);
- slow-acting (from 10 to 100 ms);

The stationary installation option is considered basic. There are also roll-out models; they are supplied complete with trolley and landing nest.

Circuit breakers consist of the following main components:

Contact system;
- arc extinguishing system;
- releases;
- control mechanism;
- free release mechanism.

Contact system consists of fixed contacts fixed in the housing and movable contacts hinged on the axle axis of the control mechanism lever, and usually provides a single circuit break.

Arcing device is installed in each pole of the switch and is intended to localize the electric arc in a limited volume. It is an arc-extinguishing chamber with a deion grid made of steel plates. Spark arrestors in the form of fiber plates may also be provided.

Free release mechanism is a hinged 3- or 4-bar mechanism that provides disengagement and disconnection of the contact system for both automatic and manual control.

Electromagnetic overcurrent release, which is an electromagnet with an armature, ensures automatic tripping of the circuit breaker at short-circuit currents exceeding the current setting. Electromagnetic current releases with a hydraulic delay device have an inverse current time delay to protect against overload currents.

Thermal overload release is a thermobimetallic plate. During overload currents, the deformation and forces of this plate ensure automatic tripping of the circuit breaker. The time delay decreases as the current increases.

Semiconductor releases consist of a measuring element, a block of semiconductor relays and an output electromagnet that acts on the free release mechanism of the machine. A current transformer (AC) or a choke magnetic amplifier (DC) is used as a measuring element.

The semiconductor current release allows the following parameters to be adjusted:

Release base current;
- settings for operating current in the zone of short circuit currents (cut-off current);
- settings for response time in the overload current zone;
- settings for response time in the zone of short-circuit currents (for selective switches).

At the Alexma company you can buy VA automatic switches of various models: VA04-36, VA52-39, VA51-25, VA51-35M, VA51-39, VA57-35, VA55-43, VA53-41 and others in different versions . You can easily place an order through the online contact form with the operator, by phone, or simply send a request by fax. We offer high-quality products of our own production and those produced by other time-tested companies. Call us!