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Independent release. Circuit breaker release: main types and their features Types of releases

In each electrical circuit Various protective devices are installed. Quite often, in addition to them, it is used independent release, connected to circuit breaker mechanically. If conditions arise that threaten damage to the devices and the line itself, it promptly breaks the electrical circuit. This usually occurs when there is a short circuit, breakdowns and leaks, as well as an increase in current strength above rated limits that are dangerous for cables and wires.

General design of the release and connection diagram

Each independent release is a device that is used to remotely switch off protective equipment. As a rule, it is used in conjunction with various circuit breakers - with one, two, three or four poles. Usually the release is connected to the input circuit breaker and when emergency situation produces a complete de-energization of the shield.

The design of the release is made in the form of an electromagnet. When it receives a short-term impulse, the device uses a special lever to influence the mechanism that turns off the automatic protective device. The electromagnetic coils used in the design can be different, designed for alternating or direct current with a voltage of 12-60 V and 110-415 V, in accordance with one or another modification. Attachment to the machine also depends on the specific model and is performed on the right or left side.

From correct connection a trip unit with a protective device depends on the precise operation of the entire system.

The normal operation of both devices largely depends on compliance with all the requirements of the connection diagram. For example, phase conductors must be connected from the lower phase terminals of the machine. If this condition is not met, there is a high probability of failure of an incorrectly connected release. Normally, the circuit breaker with an independent release should turn off and the voltage from the device coil should disappear.

Remote control of operation is carried out using a normally open contact of one of the devices fire alarm or by pressing a regular button with normally open contacts. Using a similar scheme, several tripping devices are switched off at once, distributed into separate groups.

Independent release for circuit breakers

As already noted, this device is an additional protective element of the electrical circuit. It is used to remotely switch off circuit breakers or load switches.

The independent release is most widely used in the design of ventilation systems. In accordance with regulatory documents, in the event of a fire, ventilation must be turned off very quickly. Therefore, to the input machine installed in the switchboard serving ventilation system, an independent release is additionally connected.

Modular circuit breakers are installed in electrical panels designed for currents up to 100 amperes. The common input is in most cases protected by a load switch. It is to this that an independent tripping device is connected, which shuts down in emergency situations. If the input current is over 100 A, installation of a more powerful circuit breaker is required. You can also select the most suitable independent release for it.

Using this device, it is possible to disconnect not only single-phase, but also three-phase equipment. In order for the release to start operating, one voltage pulse is applied to its coil. The release is returned to its original state using the “return” button. Manually pressing it indicates remote tripping rather than tripping due to a short circuit.

Triggering of independent releases can occur due to various reasons. The most widespread are the following:

  • Excessive voltage surges either up or down.
  • Violation set parameters, change in state of electric current.
  • Malfunction of machines, inability to perform their functions.

There are similar disconnecting devices used in conjunction with circuit breakers. They perform the same functions, but according to the principle of operation they are thermal and electromagnetic.

Thermal releases of automatic machines

The main element of thermal tripping devices is a bimetallic plate. It is made of two metals, each of which has own coefficient thermal expansion.

Both metals are pressed together and during heating they experience different degrees of expansion, which in turn causes deformation and curvature of the plate. If the current situation does not return to normal over a certain period of time, then the plate, under the influence of rising temperature, will touch the contacts of the machine, turning off the electrical circuit.

Thus, triggering thermal release is caused by an increase in the temperature of the plate under the influence of excessive load in any area under the protection of the machine. That is, a strictly limited number of devices and equipment can be connected to a wire or cable with a certain cross-section. If you try to turn on another device, general power devices will exceed its permissible value for of this cable. The current will begin to increase and cause the conductor to heat up. Severe overheating often leads to melting of the insulating layer and fire.

This situation is prevented by the operation of a thermal release. The bimetallic plate heats up along with the wire, and after some time its bending, acting on the machine, turns off the current supply. After cooling, the protective device is switched on manually, first turning off the devices that caused the overload. Without this procedure, the machine will turn off again after a while.

The use of a thermal release requires an exact match to the cross-section of the given cable. Failure to comply with this condition will result in trips even under normal loads. And, conversely, if the current is dangerously high, the release will not react and the wiring will fail.

Automatic machines with electromagnetic releases

Switching devices, which include an independent release and a thermal release, are complemented by an electromagnetic device with similar functions.

The need for their use is dictated by the specifics of thermal releases, which cannot operate instantly and perform a shutdown only for one second or more. Due to this, they cannot provide effective protection from short circuits. Therefore, in addition to the thermal one, another tripping device is installed - electromagnetic.

The design of electromagnetic devices consists of an inductor - a solenoid and a core. In normal operating mode of the circuit, electrons pass through the solenoid and form a weak magnetic field that does not affect the overall performance of the network. When a short circuit occurs, the current instantly increases many times. At the same time, there is a proportional increase in power magnetic field. Under its influence, an instantaneous shift of the core occurs, affecting the tripping mechanism. This prevents serious consequences from short circuit overcurrents.

How to check the serviceability and functionality of the release

This check should only be performed qualified specialists. The actions are performed in the following order:

  • Visual inspection of the surface of the case for chips, cracks and other defects.
  • Make a few clicks of the switch. The lever should move easily into all positions.
  • At the next stage, you need to perform the so-called loading of the device by creating unfavorable conditions. This will require special equipment and the presence of a qualified electrical technician. The main testing indicator is the time interval from the moment the current increases until the device is completely turned off. Exactly the same procedure is performed on the device with the housing removed.
  • When checking the thermal release, it is imperative to set the time required to switch off the device affected by increased strength current

Circuit breakers are devices that are intended for protective shutdown DC circuits and alternating current in cases of short circuit, current overload, voltage drop or disappearance. Unlike fuses, automatic switches have a more accurate shutdown current, can be used repeatedly, and also in a three-phase design, when a fuse trips, one of the phases (one or two) may remain energized, which is also an emergency mode of operation (especially when powered three-phase electric motors).

Circuit breakers are classified according to the functions they perform, such as:

  • Minimum and maximum current machines;
  • Minimum voltage circuit breakers;
  • Reverse power;

We will look at the principle of operation of a circuit breaker using the example of an overcurrent circuit breaker. Its diagram is shown below:

Where: 1 – electromagnet, 2 – armature, 3, 7 – springs, 4 – axis along which the armature moves, 5 – latch, 6 – lever, 8 – power contact.

When the rated current flows, the system operates normally. As soon as the current exceeds the permissible setting value, the electromagnet 1 connected in series with the circuit will overcome the force of the restraining spring 3 and retract the armature 2, and turning through the axis 4, the latch 5 will release the lever 6. Then the tripping spring 7 will open the power contacts 8. Such a machine is turned on manually.

Currently, automatic machines have been created that have a shutdown time of 0.02 - 0.007 s for shutdown currents of 3000 - 5000 A.

Circuit breaker designs

There are quite a lot various designs circuit breakers of both AC and AC circuits direct current. IN Lately Small-sized automatic machines, which are intended for protection against short circuits and current overloads household and industrial networks in installations for currents up to 50 A and voltage up to 380 V.

Main protective agent in such switches are bimetallic or electromagnetic elements, triggered with a certain time delay when heated. Automatic machines that contain an electromagnet have a fairly high operating speed, and this factor is very important in case of short circuits.

Below is a cork machine with a current of 6 A and a voltage not exceeding 250 V:

Where: 1 – electromagnet, 2 – bimetallic plate, 3, 4 – on and off buttons, respectively, 5 – release.

The bimetallic plate, like the electromagnet, is connected in series to the circuit. If more than rated current flows through the circuit breaker, the plate begins to heat up. When an excess current flows for a long time, plate 2 is deformed due to heating, and affects the release mechanism 5. If a short circuit occurs in the circuit, electromagnet 1 will instantly retract the core and thereby also influence the release, which will open the circuit. Also, this type of machine is turned off manually by pressing button 4, and turned on only manually by pressing button 3. The release mechanism is made in the form of a breaking lever or latch. Fundamental electrical diagram machine is shown below:

Where: 1 – electromagnet, 2 – bimetallic plate.

The operating principle of three-phase circuit breakers is practically no different from single-phase ones. Three-phase switches are equipped with special arc-extinguishing chambers or coils, depending on the power of the devices.

Below is a video detailing the operation of the circuit breaker:

How does a circuit breaker work?

Normal operating mode of the machine at rated or low current. The operating current passes through the upper terminal of the machine, through the pendant contact, through the coil electromagnetic release, then passes through the thermal release mechanism and the lower terminal of the machine. When the current exceeds the nominal value, electromagnetic or thermal protection is triggered.

Types of circuit breakers

In order to protect against overcurrent, the machine uses a thermal release as overload protection - this is a bimetallic narrow strip of plate assembled from two types of alloys that have different coefficients of thermal expansion.

The composite bimetallic plate is heated by the flowing current and bends towards the metal with a slight expansion. When the current is greater than the rated value, then over time the plate bends so much that this bending is enough for the thermal protection to respond. The time at which the release reacts depends on the degree of excess relative to the rated current.

With a significant increase in current rating, thermal protection will turn off the circuit breaker faster than with a small excess of the rating. The second type of circuit breaker protection is triggered by a short circuit in the load - this is an electromagnetic release. It consists of copper coil with a metal core. Relative to the magnitude of the passing current, the electromagnetic field of the coil also increases, which magnetizes the steel core.

Demonstration of machine mechanisms

The magnetized core is attracted, overcoming the force of the spring holding it, pushes the mechanism electromagnetic protection and breaks contacts. Rated current and the current a little higher is not enough to magnetize the core so that the release mechanism operates. And the short circuit current creates a magnetization of the core sufficient to turn off the machine in hundredths of a second or even less.

Protection of the machine under different overloads

Thermal release mechanism will not work with a small and short-lived current above the rated current. If the current duration is greater than the rated one, the thermal release will operate. The time it takes to turn off the machine by thermal protection can reach up to an hour.

Circuit breaker mechanisms

The time delay allows you not to turn off the circuit breakers in case of significant starting currents of the engine and short-term surges of current. thermal releases also depends on ambient temperature. At elevated temperatures, thermal protection will work faster than in the cold.

You can cause an overload by turning on several household appliances- a kettle, a washing machine, an air conditioner, an electric stove. When overloaded, the machine turns off, but it is impossible to turn it on immediately; you need to wait for the bimetallic plate to cool down.

Operation of the machine during a short circuit

Large short circuit currents can melt electrical wiring or burn insulation. To save electrical wiring, use electromagnetic release. In case of short circuits, the mechanics of the electromagnetic release are triggered instantly, protecting the electrical wiring, and it does not have time to heat up.

However, when the contacts open, an electric arc with enormous temperature appears. An arc-extinguishing chamber is designed to protect against burnt contacts and destruction of the housing. Structurally, the chamber consists of an element with a set of thin copper plates with a small gap.

Electromagnetic and thermal protection of circuit breaker

Electric arc touching a set of plates through copper wire connected to the contact, falls apart, cools down and disappears. When a short circuit occurs, gases are formed that escape through the holes in the chamber. To turn the machine back on, you need to eliminate the cause of the short circuit, or the machine will turn off again.

The culprit of the short circuit can be determined by sequential shutdown household electrical appliances. But if after turning off all the devices the short circuit does not disappear, then there is a high probability that it originated in the electrical wiring. A short circuit condition can be caused by electric lighting devices, which also need to be turned off.

It is easier and cheaper to prevent the fire-hazardous consequences of destruction than to bitterly complain about the measures not taken. Preventing electrical fires involves installing protective equipment. In the last century, the function of protection against short circuits and the danger of overload was entrusted to porcelain fuses with replaceable fuse links, then to automatic plugs. However, due to a significant increase in the load on power lines, the situation has changed. It's time to change outdated devices for reliable machines. In order for the selection of a circuit breaker to result in the purchase of a device with the appropriate characteristics, information about a number of electrical technical nuances is required.

Why do we need machine guns?

Circuit breakers are devices designed to protect power cable, more precisely, its isolation from melting and loss of integrity. The machines do not protect equipment owners from impacts and do not protect the equipment itself. For these purposes, an RCD is equipped. The task of the machines is to prevent overheating that accompanies the flow of overcurrents to the entrusted section of the circuit. Thanks to their use, the insulation will not melt or be damaged, which means that the wiring will operate normally without the risk of fire.

The operation of circuit breakers is to open the electrical circuit in the event of:

  • the appearance of short circuit currents (hereinafter short circuit currents);
  • overload, i.e. the passage of currents through the protected section of the network, the strength of which exceeds the permissible operational value, but is not considered a TKZ;
  • noticeable reduction or complete disappearance of tension.

The machines guard the section of the chain that follows them. Simply put, they are installed at the input. They protect lighting lines and sockets, lines for connecting household equipment and electric motors in private homes. These lines are laid with cables of different sections, because equipment of different power is powered from them. Consequently, to protect network sections with unequal parameters, protection devices with unequal capabilities are needed.

If you want to learn how to install socket boxes, we recommend that you read the article

It would seem that you can, without unnecessary hassle, purchase the most powerful automatic shutdown devices for installation on each of the lines. The step is completely wrong! And the result will pave a direct “path” to the fire. Protection from the vagaries of electric current is a delicate matter. Therefore, it is better to learn how to choose a circuit breaker and install a device that breaks the circuit when there is a real need for it.

Attention. An overrated circuit breaker will carry currents that are critical to the wiring. It will not disconnect the protected section of the circuit in a timely manner, which will cause the cable insulation to melt or burn.

Automatic machines with reduced characteristics will also present many surprises. They will endlessly break the line when starting up the equipment and will eventually break due to repeated exposure to too much current. The contacts are soldered together, which is called “stuck”.

Design and principle of operation of the machine

It will be difficult to make a choice without understanding the circuit breaker design. Let's see what's hidden in a miniature box made of refractory dielectric plastic.

Releases: their types and purpose

The main working parts of automatic circuit breakers are releases that break the circuit in case of exceeding the standard operational parameters. Releases differ in the specificity of their action and in the range of currents to which they must respond. Their ranks include:

  • electromagnetic releases, which react almost instantly to the occurrence of a fault and “cut off” the protected section of the network in hundredths or thousandths of a second. They consist of a coil with a spring and a core, which is retracted from the effects of overcurrents. By retracting, the core strains the spring, and it causes the release device to work;
  • thermal bimetallic releases, acting as a barrier against overloads. They undoubtedly also respond to TKZ, but are required to perform a slightly different function. The task of thermal counterparts is to break the network if currents passing through it exceed the maximum operating parameters of the cable. For example, if a current of 35A flows through the wiring intended to transport 16A, the plate consisting of two metals will bend and cause the machine to turn off. Moreover, she will courageously “hold” 19A for more than an hour. But 23A won’t be able to “tolerate” for an hour; it will work earlier;
  • semiconductor releases are rarely used in household machines. However, they can serve as the working body of a protective switch at the input a private house or on line powerful electric motor. Measurement and recording of abnormal current in them is carried out by transformers, if the device is installed on an alternating current network, or choke amplifiers, if the device is connected to a direct current line. The decoupling is carried out by a block of semiconductor relays.

There are also zero or minimum releases, most often used as a supplement. They disconnect the network when the voltage drops to any limit value specified in the data sheet. A good option are remote releases that allow you to turn the machine off and on without opening the control cabinet, and locks that fix the “off” position. It is worth considering that equipping with these useful additions significantly affects the price of the device.

Automatic machines used in everyday life are most often equipped with a smoothly working combination of an electromagnetic and thermal release. Devices with one of these devices are much less common and used. Still circuit breakers combined type more practical: two in one is more profitable in every sense.

Extremely Important Additions

There are no useless components in the design of the circuit breaker. All components work diligently in the name of overall safety, these are:

  • an arc extinguishing device mounted on each pole of the machine, of which there are from one to four pieces. It is a chamber in which, by definition, the electric arc that occurs when the power contacts are forced to open is extinguished. Copper-plated steel plates are located in parallel in the chamber, dividing the arc into small parts. The fragmented threat to the fusible parts of the machine in the arc extinguishing system cools down and completely disappears. Combustion products are removed through gas outlet channels. An addition is a spark arrester;
  • a system of contacts, divided into fixed ones, mounted in the housing, and movable ones, hingedly attached to the axle shafts of the levers of the opening mechanisms;
  • calibration screw, with which the thermal release is adjusted at the factory;
  • a mechanism with the traditional inscription “on/off” with a corresponding function and with a handle intended for implementation;
  • connection terminals and other devices for connection and installation.

This is what the arc extinguishing process looks like:

Let's linger a little on power contacts. The fixed version is soldered with electromechanical silver, which optimizes the electrical wear resistance of the switch. When an unscrupulous manufacturer uses a cheap silver alloy, the weight of the product decreases. Silver-plated brass is sometimes used. “Substitutes” are lighter than standard metal, which is why a high-quality device from a reputable brand weighs slightly more than its “left-hand” analogue. It is important to note that when replacing silver soldering of fixed contacts with cheap alloys, the service life of the machine is reduced. It will withstand fewer cycles of turning off and then turning on.

Let's decide on the number of poles

It has already been mentioned that this protection device can have from 1 to 4 poles. Selecting the number of machine poles is as easy as shelling pears, because it all depends on its purpose of use:

  • A single-pole circuit breaker will do an excellent job of protecting lighting lines and sockets. Mounted only on a phase, no zeros!;
  • a two-pole switch will protect the cable supplying electric stoves, washing machines and water heaters. If powerful household appliances not in the house, it is placed on a line from the panel to the entrance to the apartment;
  • a three-pole device is required for three-phase wiring equipment. This is already on a semi-industrial scale. In everyday life there may be a workshop line or well pump. A three-pole device must not be connected to the ground wire. He must always be in full combat readiness;
  • Four-pole circuit breakers are used to protect four-wire wiring from fire.

If you plan to protect the wiring of an apartment, bathhouse, or house using two-pole and single-pole circuit breakers, first install a two-pole device, then a single-pole device with the maximum rating, then in descending order. The “ranking” principle: from the more powerful component to the weaker but sensitive one.

Labeling – food for thought

We figured out the structure and operating principle of the machines. We found out what and why. Now let’s boldly begin to analyze the markings affixed to each circuit breaker, regardless of the logo and country of origin.

The main reference point is the denomination

Because The purpose of purchasing and installing a machine is to protect the wiring, so first of all you need to focus on its characteristics. The current flowing through the wires heats the cable in proportion to the resistance of its current-carrying core. In short, the thicker the vein, the greater value current can pass through it without melting the insulation.

In accordance with the maximum value of the current transported by the cable, the rating of the device is selected automatic shutdown. There is no need to calculate anything; the interdependent values ​​of electrical installation devices and wiring by caring electricians have long been summarized in the table:

The tabular information should be slightly adjusted according to domestic realities. Predominant amount household sockets designed to connect a wire with a conductor of 2.5 mm², which, according to the table, suggests the possibility of installing a machine with a rating of 25A. The actual rating of the outlet itself is only 16A, which means you need to buy a circuit breaker with a rating equal to the rating of the outlet.

A similar adjustment should be made if there are doubts about the quality of the existing wiring. If there are suspicions that the cable cross-section may not correspond to the size specified by the manufacturer, it is better to play it safe and take a machine whose nominal value is one position lower than the table value. For example: according to the table, an 18A machine is suitable for cable protection, but we’ll take a 16A one, because we bought the wire from Vasya at the market.

Calibrated characteristic of the device rating

This characteristic is the operating parameters of a thermal release or its semiconductor analogue. It is a coefficient by which we multiply to obtain the overload current that the device may or may not hold for a certain period of time. The value of the calibrated characteristic is established during the production process and cannot be adjusted at home. They select it from the standard range.

The calibrated characteristic indicates how long and what kind of overload the machine can withstand without disconnecting the circuit section from the power supply. Usually these are two numbers:

  • the lowest value indicates that the machine will pass current with parameters exceeding the standard for more than an hour. For example: a 25A circuit breaker will pass a current of 33A for more than an hour without disconnecting the protected section of wiring;
  • the highest value is the limit beyond which shutdown will occur in less than an hour. The device indicated in the example will quickly turn off at a current of 37 amperes or more.

If the wiring runs in a groove formed in a wall with impressive insulation, the cable will practically not cool during overload and the accompanying overheating. This means that in an hour the wiring can suffer quite a bit. Maybe no one will immediately notice the result of the excess, but the service life of the wires will be significantly reduced. Therefore, for hidden wiring We will look for a switch with minimal calibration characteristics. For open version You don’t have to focus too much on this value.

Setting – instantaneous response indicator

This number on the body is a characteristic of the operation of the electromagnetic release. It indicates the maximum value of the abnormal current, which during repeated shutdowns will not affect the performance of the device. It is standardized in units of current, and is indicated in numbers or Latin letters. With numbers, everything is extremely simple: this is the face value. And here hidden meaning letter designations It's worth finding out.

Letters are stamped on machines made according to DIN standards. They indicate the multiple of the maximum current that occurs when the equipment is turned on. A current that is several times greater than the operating characteristics of the circuit, but does not cause a shutdown and does not render the device unusable. Simply, how many times the equipment switching current can exceed the rating of the device and cable without dangerous consequences.

For circuit breakers used in everyday life, these are:

  • IN– designation of machines capable of reacting without self-damage to currents exceeding the nominal value in the range from 3 to 5 times. Very suitable for equipping old buildings and rural areas. They are not used often, therefore they are most often a custom item for retail chains;
  • WITH– designation of these protective equipment, the response range of which is from 5 to 10 times. The most common option, in demand in new buildings and new country houses with autonomous communications;
  • D- designation of switches that instantly break the network when a current is supplied with a force exceeding the nominal value from 10 to 14, sometimes up to 20 times. Devices with such characteristics are needed only to protect the wiring of powerful electric motors.

There are variations abroad, both higher and lower, but the average owner of domestic property should not be interested in them.

Current limiting class and its meaning

Let's talk about this briefly, because most of the devices offered by trade belong to the 3rd class of current limitation. Occasionally there is a second one. This is an indicator of the speed of the device. The higher it is, the faster the device will respond to TKZ.

There is a lot of information, but without it it will be difficult to choose the right circuit breaker and protect property from unwanted fires. Information is also needed for those who will order the installation of protection devices. After all, not every electrician who positions himself as a great specialist should be trusted unconditionally.

Thermal release- provides protection only against overcurrent.

Electromagnetic release- provides protection only against short circuits.

Thermal-magnetic (magnetic-thermal, combined) release- consists of two types of releases - thermal and electromagnetic. Provides protection against both overcurrent and short circuits.

Thermal-magnetic (magnetic-thermal, combined) release, with protection against leakage currents- in addition to protection against overloads and short circuits, it protects people and electrical installations from ground faults.

Electronic release (the electronic unit protection - Overcurrent Release) - (depending on the version) provides the maximum number of types of protection.

Release device

Thermal release

The thermal release is a bimetallic plate that, when heated, bends and acts on the free release mechanism. A bimetallic plate is made by mechanically joining two metal strips. Two materials with different coefficients of thermal expansion are selected and connected to each other by soldering, riveting or welding.

Advantages:

  • no moving parts;
  • undemanding to pollution;
  • simplicity of design;
  • low price.

Flaws:

  • high own energy consumption;
  • sensitive to temperature changes environment;
  • when heated from third-party sources, they can cause false alarms.
Electromagnetic release

The electromagnetic release is an instantaneous device. It is a solenoid, the core of which acts on the free release mechanism. When a supercurrent flows through the solenoid winding, a magnetic field is created that moves the core, overcoming the resistance of the return spring.

The EM release can be configured (at the manufacturer's factory or by the consumer) to operate at short-circuit currents ranging from 2 to 20 In. The setting error varies approximately ±20% of the set current value for molded case switches.
For power circuit breakers, the short-circuit trip setting (the current value at which tripping is initiated) can be indicated either in amperes or as a multiple of the rated current.
There are settings: 3.5In; 7In, 10In; 12In and others.

Advantages:

  • simplicity of design;

Flaws:

  • creates a magnetic field.
Thermomagnetic release

Often used serial connection thermal and electromagnetic release. Depending on the manufacturer, this connection of two devices is called a combined or thermomagnetic release.

Thermomagnetic or combined release

Thermomagnetic release with leakage current protection

The machine with these releases, in addition to thermal and electromagnetic releases, has a unit capable of detecting fault current to the ground using toroidal transformer, which covers all live parts, as well as the neutral, if it is distributed. Earth leakage releases can be used in combination with a circuit breaker to provide two main functions in one device:

  • protection against overloads and short circuits;
  • protection against indirect contact (appearance of voltage) on conductive parts due to insulation damage).
Electronic release

A release connected to measuring current transformers (three or four, depending on the number of protected conductors), which are installed inside the circuit breaker and provide a dual function: supplying power for normal control of the release and detecting the value of the current that passes in live parts. Therefore, they are only compatible with AC power.

The signal from the transformers is processed by an electronic part (microprocessor), which compares it with the specified settings. When the signal exceeds the threshold, the circuit breaker release acts directly on the breaker tripping assembly via a trip coil.

The release control unit allows you to build a user-defined program according to which the circuit breaker will trip the main contacts.

Advantages:

  • a varied selection of settings needed by the user;
  • high accuracy of execution of a given program;
  • performance indicators and reasons for operation;
  • logic selectivity with upstream and downstream switches.
  • high price;
  • fragile block management;
  • exposure to electromagnetic fields.