If you want to read about reverse thrust of an aircraft engine, I recommend paying attention to the latest article on this topic. It was written on 03/30/13 and is located on this site in the same section entitled “Once again about thrust reversal... A little more detail... :-)”, that is. And this article (where you are now), in my opinion, no longer meets the demanding needs of both mine and my readers. However, it will remain on the site, so if you want, you can pay attention to it too... Just for comparison :-)...

Reverse operation when landing A-321.

The problem of aircraft braking after landing on the runway was probably of little significance only at the dawn of aviation, when aircraft flew slower than modern cars and were much lighter than the latter :-). But later this issue became more and more important and for modern aviation with its speed it is quite serious.

How can you slow down a plane? Well, firstly, of course, with brakes installed on a wheeled chassis. But the fact is that if the plane has a large mass and lands at a fairly high speed, then often these brakes are simply not enough. They are sometimes unable to absorb all the energy of movement of a multi-ton colossus in a short period of time. In addition, if the contact (friction) conditions between the tires of the chassis wheels and the concrete strip are not very good (for example, if the strip is wet during rain), then braking will be even worse.

However, there are two more ways. The first one is drogue parachute. The system is quite effective, but not always convenient to use. Imagine what a parachute is needed to slow down, for example, a huge Boeing 747, and what a parachute service should be like at a large airport where planes land, one might say, en masse :-).

Operation of the reverse (flap) on the JeasyJet Airbus A-319.

The second method is much more convenient in this regard. This reverse thrust engine on an airplane. In principle, this is a fairly simple device that creates reverse thrust, that is, directed against the movement of the aircraft, and thereby slows it down.

Reverse device for turbojet engines. The hydraulic cylinders for controlling the reversible flaps are visible

Thrust reverse can be created by variable pitch propeller aircraft (VPS). This is done by changing the angle of the propeller blades to a position where the propeller begins to “pull” back. And on jet engines this is done by changing the direction of the outgoing jet stream using reverse devices, most often made in the form of flaps that redirect the jet stream. Since the loads there are multi-ton, these doors are controlled using a hydraulic system.

Reverse on a KLM Fokker F-100.

The main application of thrust reverser is braking during a run. But it can also be used for emergency braking if it is necessary to stop takeoff. Less often and not on all aircraft, this mode can be used when taxiing at an airfield to move in reverse, then there is no need for a towing vehicle. The Swedish fighter Saab-37 Viggen is very typical in this regard. Its evolution can be seen in the video at the end of the article.

Saab 37 Viggen fighter.

However, to be fair, it should be said that it is almost the only plane that can travel in reverse so easily :-). In general, reverse thrust on jet engines is rarely used on small aircraft (). It is mainly used on commercial and civil aviation aircraft and on airplanes.

It is worth saying that some aircraft provide for the use of thrust reverser in flight (an example of this is the ATR-72 passenger aircraft). This is usually possible for an emergency reduction. However, restrictions are imposed on these types of modes and they are practically not used in normal flight operation.

Airplane ATR-72.

The aircraft, however, with all its advantages and disadvantages. The first is the weight of the device itself. For aviation, weight plays a big role and often because of it (and also because of the dimensions), the reverse device is not used on military fighters. And the second is that the redirected jet stream, when hitting the runway and surrounding soil, is capable of raising dust and debris into the air, which can get into the engine and damage the compressor blades. This danger is more likely at low aircraft speeds (up to about 140 km/h); at high speeds, the debris simply does not have time to reach the air intake. Dealing with this is quite difficult. The cleanliness of the runway (runway) and taxiways is generally an ongoing problem at airfields, and I will talk about it in one of the following articles.

Airplane Yak-42

It is worth saying that there are aircraft that do not require jet engine thrust reversers. These are such as, for example, the Russian Yak-42 and the English BAe 146-200. Both have advanced wing mechanization, which significantly improves their takeoff and landing characteristics. The second plane is especially indicative in this regard. In addition to mechanization, it has tail air brakes (flaps), which allow it to effectively reduce speed during descent and after landing on the run (coupled with the use of spoilers). There is no need for reverse, which makes this aircraft convenient for use at airports located within the city and therefore sensitive to noise, as well as those with a steep approach pattern (for example, London City Airport).

Aircraft BAe 146-200. The open brake flaps in the tail are clearly visible.

However, there are still not so many aircraft of this kind, but reverse thrust The system is already quite well developed, and the operation of airports today is unthinkable without it.

In conclusion, I suggest you watch videos in which the operation of the reverse mechanisms is clearly visible. You can see how the reversed jet lifts water from the concrete. And, of course, the SAAB “reverse” :-). It's better to watch in full screen :-)..

Photos are clickable.

In the household, you have to use various devices that help make it easier to complete some task. In some cases, you have to assemble a specific tool to meet your needs, which is quite expensive or you simply have all the necessary components for it. Often for this it is important to know how to make an electric motor connection diagram. Making it rotate is not so difficult, but changing the direction of movement is more difficult. The article will tell you how to make a reverse motor connection circuit.

Principle of operation

An electric motor is a mechanism in which rotation is carried out under the influence of electromagnetic waves. It is based on only two components:

  • rotor;
  • stator.

Only the first element rotates, and the impulse is supplied to it from the second element. The higher the engine power, the larger its dimensions. From all the variety there are:

  • collector;
  • asynchronous.

In commutator-type motors, power is supplied to the rotor through carbon brushes that touch the commutator lamellas. Such motors are also called squirrel-cage motors. In asynchronous motors, the operation scheme is somewhat different. In this case, rotation occurs under the influence of two forces:

  • magnetic field;
  • induction.

The voltage from the power source is supplied to the fixed stator windings. At the same time, electromagnetic waves arise in it. If the voltage is variable, then the magnetic field is unstable and has certain fluctuations. Thanks to these vibrations, the rotor shifts. There is a small air gap between the rotor and stator, thanks to which unhindered displacement is possible. Magnetic waves from the stator windings affect the rotor windings, creating voltage. Due to this effect, electromotive force or EMF arises. It causes magnetic waves to interact in the opposite direction with what is in the stator, which is why the motor is called asynchronous.

Note! Most often, asynchronous motors have a three-phase connection. Thanks to the use of additional components, it can be converted to operate on a 220 volt network.

Required Components

Independently connecting the motor for reverse rotation will not cause any particular difficulties if you follow the diagram provided. One of the important components that will facilitate this task is a magnetic starter or contactor. In fact, a magnetic starter and a contactor are not identical concepts. To put it simply, the contactor is part of the magnetic starter, but for simplicity, in the article both concepts are used as equivalent. Magnetic starters are precisely used for starting, reversing and stopping asynchronous motors.

Perhaps the question arises as to why you can’t use a regular switch or power circuit breaker. In principle, this is acceptable, but the starting currents that the engine needs for normal operation are not always safe for humans. When switched on, a breakdown may occur, which will damage both the switch and harm the operator. To minimize risks, you will need a starter. In it, the contact part is separated from the one with which the operator interacts. It contains a separate module with a coil that creates an electromagnetic field. The coil may require 12 volts or more to operate. When this voltage is applied, it interacts with the metal core, which is pulled into the coil. A plate is attached to the core, which goes to the contact group. They close and the engine starts. Stopping occurs in reverse order.

In addition to the contactor, you will need a three-button station. One key performs the stop function, and the other two start functions with a difference in the direction of rotation. A three-button station must have two normally open contacts and one normally closed. Simply put, the normal position of the contactor is its non-operating position. That is, when a contact is acted upon, it either closes or opens. If in operating condition it is closed, it is designated as NO, and if it is open, it is designated as NC. The NC contact is used for the stop button.

Schematic diagram

In the illustration above you can see a schematic diagram of a reversible motor connection. It differs from the usual one only in the presence of an additional module. To be more precise, the circuit uses two control modules. One of them causes the engine to rotate to the right, and the other to the left. The operator interacts with the modules using the SB2 and SB3 buttons. The Latin letters A, B, C in the diagram indicate the supply lines of a three-phase network. They fit into a common switch, which is designated QF1. Next come two contactors KM and a digital designation. From the contactors the circuit goes to the motor windings. Each of these contactors is displayed separately and is located on the right, where you can further examine their components.

Power-up process

The process of turning on the engine is quite simple to describe using the same diagram. The first step is to activate the general switch QF1. As soon as it turns on, voltage is supplied in three phases. But this voltage is not applied directly to the motor itself, since there are still no clear indications in which direction it should rotate. Next, the conductors pass through the SF1 circuit breaker; it performs a protective function, de-energizing the entire system in the event of a short circuit. Next comes the shutdown button, which can also quickly open the power circuit. Only after this does the voltage flow to the SB2 and SB3 keys, after acting on which, the power flows to the engine.

Note! The diagram clearly shows that two contactors cannot be activated at the same time, so a failure cannot occur.

In order for the engine to receive sufficient force for reverse rotation, it is necessary to switch the power phases, which is what the KM2 starter is designed for. If you look at the diagram again, you will notice that the KM1 starter has a direct phase connection to the motor, and KM2 provides some bias. Everything happens at the expense of the first phase, which in this scheme is waiting. As soon as it opens, the voltage supply to the motor is stopped.

Note! In the reversible motor connection circuit, there must be an additional protective module that will ensure that the motor is stopped before starting a new cycle.

After a complete stop, the SB3 button can be activated. It activates the second starter. The latter changes the position of the phases, as shown in the diagram. In this case, the standby phase remains unchanged, power from it is still supplied to the first contact of the motor. Changes occur in the second and third phases. This ensures reverse movement.

Connection steps

Connecting the motor for reverse movement differs depending on which network will supply 220 or 380. Therefore, it makes sense to consider them separately.

To a three-phase network

Guided by the presented diagram, it is easy to create a sequence in which the electric motor should be connected. The first step is to install the main power machine. Its rated voltage and current must be designed for those that the motor will consume. Only in this case can you be sure of uninterrupted operation. Before installing the machine, you will need to turn off the power to the engine. The safety switch is installed next. After this, the phase cable goes to the break, to the stop button, and from there a connection is made to the contactors. Each element of the contactor and push-button post is usually marked with appropriate markings that simplify the connection process. A video about assembling the test circuit can be viewed below.

To a single-phase network

At home, you often have to use an asynchronous motor, but not every household has a three-phase network, so it is important to know how to connect the motor to a single-phase network. To start from one phase, an additional impulse is required; to provide it, a capacitor of the required capacity is selected. To put it simply, there should be two capacitors. One of them is the starting one and is connected in parallel with the first. The connection of the motor windings is carried out according to the “star” circuit. If the windings are connected in a different way and there is no way to change it, then it will not be possible to complete the required circuit.

In order for the reversible circuit to function, it will be necessary to switch the power that comes from the capacitors between the poles. You will need two switches and one non-fixed button. One of the switches will be responsible for supplying voltage to the engine power circuit. The second switch must have three positions. In one of them it will be turned off, and in the other two it will change the power supply from the capacitors to the windings. A non-fixed button will additionally connect a second capacitor when the engine starts.

The two terminals of the capacitor are connected to each other. The start button is connected to the other two. The middle terminal of the three-position switch is connected to the capacitors in the place where they are connected to each other. The other two pins are connected to the motor terminals, which receive power. Capacitors are connected to the output of the winding, which is used for starting. The power button is placed in the break of the phase wire.

To power the entire mechanism, it is necessary to supply power to the motor circuit using the main switch. After this, the direction of rotation of the engine is set using a three-position switch. Next, the start button is pressed until the engine reaches operating speed. If there is a need to change the direction of rotation, then you will need to de-energize the engine and wait until it stops completely, switch the three-position toggle switch to the opposite extreme position and repeat the process.

Summary

As you can see, reverse connection requires certain skills, but can be carried out without much difficulty if all recommendations are followed. Now there will be no obstacles to the use of three-phase units from a single-phase network, but it should be understood that the maximum power will be limited, since it is impossible to reach full consumption. It is better not to skimp on connection components, as this will affect the service life of the entire circuit. During assembly and startup, you must adhere to all safety rules for working with electric current.

An electromagnetic starter is a low-voltage combined electromechanical device specialized for starting three-phase electric motors, to ensure their continuous operation, to turn off the power, and in some cases to protect the electric motor circuits and other connected circuits. Certain engines have a motor reverse function.

In essence, an electromagnetic starter is an improved, modified contactor. But more compact than a contactor in the usual sense: lighter in weight and designed directly for working with motors. Certain modifications are magnetic x starters are optionally equipped with a thermal microrelay for emergency shutdown and protection against phase loss.

To control the start of the motor by closing the contacts of the device, a key or a low-current group of contacts is intended:

  • with a coil for a certain voltage;
  • in some cases, both.

In the starter, the coil in the metal core is directly responsible for switching the power contacts, to which the armature is pressed, pressing on the contacts and closing the circuit. When the power to the coil is turned off, the return spring moves the armature to the opposite position - the circuit opens. Each contact is located in a special arc-extinguishing chamber.

Reversing and non-reversing starters

Devices come in various types and perform all assigned tasks.

There are two types of starters:

  • irreversible;
  • reversible.

In a reversing starter, there are two individual magnetic devices in one housing, electrically connected to each other and attached to a common base, but only one of these starters can function - either only the first, or only the second.

Reversible device is introduced through naturally closed blocking contacts, the role of which is to eliminate the synchronous activation of two groups of contacts - reversible and non-reversible, so that an interphase short circuit does not occur. Certain modifications of reversing starters are protected to provide the same function. It is possible to switch the power phases in turn so that the main function of the reversible starter is performed - changing the direction of rotation of the electric motor. The order of phase alternation has changed - the direction of the rotor has also changed.

Starter capabilities

To limit the starting current of a three-phase motor, its windings can be connected in a star, then, if the motor has reached its rated speed, switch to a delta. In this case, magnetic starters can be: open and in a housing, reversible and non-reversible, with and without overload protection.

Each electromagnetic starter has blocking and power contacts. Power switches loads. Interlocking contacts are needed for control work of contacts. Blocking and power contacts can be naturally open or normally closed. In circuit diagrams, contacts are shown in their normal state.

The ease of use of reversing starters cannot be reviewed. This includes operational control of three-phase asynchronous motors of various machines and pumps, and control of the ventilation system, fittings, right down to the locks and valves of the heating system. The possibility of remote control of starters is especially noteworthy if the electrical source of remote control switches the starter coils in a similar way to relays, and the latter safely connect power circuits.

Design of a reversible magnetic motor

The distribution of these modifications is becoming more widespread every year, as they help control an asynchronous motor at a distance. This device allows you to turn on, and turn off the engine.

The reversing starter housing consists of the following parts:

  1. Contactor.
  2. Thermal micro relay.
  3. Casing.
  4. Management tools.

After the “Start” command has been received, the circuit is closed. Next, the current begins to be transmitted to the coil. At the same time, a mechanical blocking device operates, which prevents unnecessary contacts from starting. It should be noted here that the mechanical lock also closes the contacts of the key, this makes it possible not to keep it pressed constantly, but to calmly release it. Another important part is that the second key of this device, together with the start of the entire device, will open the electrical circuit. Thanks to this, even pressure produces virtually no result, creating additional safety.

Features of the model's functioning

Pressing the Forward key activates the coil and makes contacts. At the same time, the operation of the start key is performed by constantly open contacts of the KM 1.3 device, due to which, when the key is directly released, the power to the coil acts bypass.

After introducing the first starter, it is the KM 1.2 contacts that open, which turns off the K2 coil. As a result, when you directly press the “Back” key, nothing happens. In order to turn the motor in the opposite direction, you need to press “Stop” and turn off the power to K1. All blocking contacts can return to the opposite state, after which it is possible to drive the motor in the opposite direction. Similarly, K2 is introduced and the block with contacts is turned off. Coil 2 of starter K1 is turned on. K2 contains power contacts KM2, and K1 - KM1. A five-core wire should be connected to the buttons for connection from the starter.

Connection rules

In any installation that requires starting an electric motor in the forward and opposite directions, there is certainly an electromagnetic device with a reversible circuit. Connecting such an element is not considered as difficult a task as it might seem at first glance. In addition, the need for such tasks arises quite often. For example, in drilling machines, cutting structures or elevators, if this does not apply to home use.

The fundamental difference between a three-phase circuit and a single one is the presence of an additional control circuit and a slightly modified power part. In addition, to implement switching, such an installation is equipped with a key. Such a system is usually protected from short circuits. To do this, in front of the coils themselves in the circuit, the presence of two normally closed power contacts (KM1.2 and KM2.2), placed in positions (KM1 and KM2), is provided.

Reversible connection of a three-phase motor

When switch QF1 is operating, simultaneously all three phases, without exception, are adjacent to the contacts of the starter (KM1 and KM2) and are in this state. In this case, the first stage, which represents power for the control circuit, flowing through the protection device of the control circuit SF1 and the shutdown key SB1, directly supplies voltage to the contacts under the third number, which refers to SB2, SB3. In this case, the existing contact 13NO takes on the role of the main duty officer. In this way, the system is considered completely ready for operation.

System switching during counter rotation

By using the SB2 key, we direct the first phase voltage to the coil, which relates to the KM1 starter. After this, normally open contacts are introduced and normally closed contacts are turned off. In a similar way, by closing the existing contact KM1, the effect of self-capture of the magnetic device occurs. In this case, all three phases, without exception, are supplied to the required winding of the motor, which, in turn, begins to generate rotational movement.

The created model provides for the presence of one working device. For example, only KM1 or, on the contrary, KM2 can function. The marked chain has real elements.

Changing the turning motion

Now, to give the opposite direction of movement, you should change the state of the power phases, what is convenient to do using switch KM2. Everything is accomplished thanks to the opening of the first phase. In this case, all contacts without exception will return to their original state, de-energizing the motor winding. This phase is considered standby mode.

Using the SB3 key activates the KM2 electromagnetic starter, which in turn changes the position of the second and third phases. This influence forces the motor to rotate in the opposite direction. Now KM2 will be the leader, and until it is disconnected, KM1 will not be used.

Circuit short circuit protection

As already stated before, before carrying out the phase change process, it is necessary to stop the rotation of the motor. For this purpose, the system takes into account normally closed contacts. Because if there is a shortage of them, operator inattention would lead to an interphase direct short circuit, which can occur in the motor winding of the second and third phases. The proposed model is considered optimal, since it allows the operation of only one magnetic starter.

The connection diagram of a reversible magnetic starter is considered the core of the control, since a lot of electrical equipment operates in reverse, and this device directly changes the direction of rotation of the motor.

Reversing circuits electromagnetic starters are installed where they are actually needed, since similar devices exist, and the reverse process is unacceptable and can cause serious automatic damage.

Although the reverse switching of three-phase asynchronous motors is used quite often, nevertheless, ordinary people still ask the question of how to implement it.

As it turned out, the vast majority of asynchronous electric motors, both in everyday life and in production, are connected via.

This is due to the fact that such a connection circuit has fairly good reliability; in addition, protection devices against overload, phase wire breakage and phase imbalance are very easily built into their supply circuits.

Simply put, reverse is the rotation of the engine shaft in the opposite direction.

In this article I will look at a diagram for connecting a motor to reverse using a pair of magnetic starters and a three-button remote control.

The version of the scheme given in this article can be considered the simplest. More complex reverse switching schemes may contain several blocking options.

These interlocks can be either electrical or mechanical. The first ones are performed on the buttons that turn on the starters, and the second one is performed on the moving parts of the starters.

The implementation of reverse occurs by changing the phasing of the engine supply voltage.

For example, if you designate the motor power terminals as 1, 2 and 3 (the phase wires of the network are usually designated A, B and C), then when A -> 1, B -> 2 and C -> 3 are connected, the motor shaft will rotate in one direction, and if you connect A -> 1, B -> 3 and C -> 2 - then in the opposite direction.

Such a circuit is implemented, as a rule, using a pair of magnetic starters in such a way that the phasing of the switching on of their power contacts is made so that their sequence differs from each other.

That is, for example, when the first starter is triggered, the motor is connected to phases in the sequence A, B and C, and when the second starter is triggered - A, C and B.

Let's look at the diagram itself (Figure 1). This circuit is made on a pair of magnetic starters KM1 and KM2. When the first one is triggered (let's assume that it will be KM1), its power contacts are closed, as a result of which the motor windings are energized in the sequence L1, L2, L3. When the second starter is triggered, the engine will be powered through its contacts, but in phasing L3, L2, L1.

The magnetic starters themselves in this version are connected according to an absolutely standard scheme, with the only difference being that a normally closed block contact of the second starter (KM2.4, KM1.4) is connected to the open circuit of the coil power supply of each of the starters. This is done so that when you press both start buttons, both starters do not trigger.

Picture 1

In addition, the circuit is designed in such a way that a normally open block contact of its starter is connected in parallel with each of the start buttons (KP). This is done so that when the start button is pressed, the starter contactor is self-locking and the button can be released.

The stop button (KS) is included in the open circuit before both starting buttons.

In addition, the circuit has one more contact connected to the open circuit of the supply circuit. This contact is connected to the starter thermal protection device (PT).

This is how such protection works: under excessive loads or (God forbid) phase imbalance, the bimetallic plates of the thermal protection system heat up, as a result of which the latter open the contact associated with them.

Returning this contact to its original state is done using a special red button on the body of the thermal protection device.

Switching reverse without pressing the “stop” button is impossible for the reason that the block contacts of opposite starters included in the circuit will not allow this. This was done for the reason that such a switch can be dangerous for the engine, not to mention the fact that at the moment of rephasing, a phase jump can easily occur.

For low-power engines, it is possible to perform reverse without pressing the stop button. To do this, it is necessary to make adjustments so that the power group of contacts of one starter opens before the auxiliary normally closed contacts of the second contact close.

Such a switching system is not at all uncommon, but is used very widely for both domestic and industrial purposes. I myself see such a connection quite often for reversing motors of fans, pumps, various machines, conveyors, etc. due to the specifics of my work.

For domestic purposes, reverse switching is used to connect motors of drilling machines, electric mills and meat grinders.

I really hope that the material in my article helped you understand the principles of reverse switching on electric motors using a pair of magnetic starters and now there will be significantly fewer questions on this topic.

Write comments, additions to the article, maybe I missed something. Take a look at, I will be glad if you find something else useful on my site. All the best.

This circuit is quite often used to connect a three-phase electric motor where operational control of the direction of rotation of the motor shaft is necessary - for example, in garage doors, pumps, various loaders, crane beams, etc.

Reversing the motor is realized by changing the phasing of its supply voltage. For example, if the order of connecting the phases to the terminals of a three-phase electric motor is conventionally taken as L1, L2, L3, then the direction of shaft rotation will be certain, opposite than when connected, say, with phasing L3, L2, L1.

A special feature of the reversible connection scheme is the use of two magnetic starters. Moreover, their main power contacts are connected to each other in such a way that when the coil of one of the starters is triggered, the phasing of the engine supply voltage will differ from the phasing when the coil of the other is triggered.

The circuit uses two magnetic starters. When the first starter KM1 is triggered, its power contacts are attracted (circled in green dotted line) and voltage with phasing L1, L2, L3 is supplied to the motor windings. When the second starter - KM2 - is triggered, the voltage to the engine will go through its power contacts KM2 (circled in red dotted line) and will already have phasing L3, L2, L1.

As you can see, here the magnetic starters are connected according to the standard circuit. Unless, in the circuit of each coil, a normally closed block contact of another starter is connected in series. This measure will prevent a short circuit in the event of mistakenly pressing both Start buttons at the same time.

Reversing magnetic starters in a single-phase network. Reversible electric motor connection diagram.