Electrical relays: operating principle, device, types, circuits, application

The relay clicked, the tester beeped - everything is in order, the relay is working. After applying a control signal to the relay, the first output will become open and the second will become closed. We apply 12 volts to the winding from the power supply or battery - the relay should clearly click. Opening the trunk from the alarm key fob If your car has an electric trunk drive, you can connect to it with a car alarm to open it from the alarm key fob. It’s not bad when the power terminals are copper, and the winding terminals are nickel-plated steel. Examples of using relays for switching various devices are given at the end of the article. How to connect the relay

Examples of relay application: Engine blocking. Power contacts are always marked as 30, 87 and 87a. To do this, we need a power source with a voltage of 12 volts, a power supply or two wires from a battery and a tester turned on in resistance measurement mode. Poor contact generates heat. Connection diagram for central locking with an additionally installed activator and activators for alarms that do not have built-in central locking interface relays. Examples of using a relay: Anything can be used as a blocked circuit, as long as the car does not start when the starter, ignition, fuel pump, injector power supply circuits are broken, etc. Switching on through side lights or low beams The second option for the DRL connection diagram involves using the power circuit of the side light bulb. This scheme already has the right to life, since you can control the operation of the DRL depending on your driving conditions.

Let's cut this wire.

Connection diagram for an electric car radiator cooling fan

The nuances of turning on running lights

And the more parts, the less reliability. I do not recommend connecting DRLs using this scheme. This seems complicated, but let's look at an example and everything will become clear. Now, if you try to start the car with the security switched on, contact 30 will open with contact 87A and will not allow the engine to start. You have no way to turn off the DRLs until you remove the key from the ignition. Actually, the current reserve never interferes - but this mainly applies to some kind of non-standard electrical equipment of the car that is connected independently. Likewise, 14.8 volts, to which the voltage in the on-board network rises when the engine is running, does not harm them. Its polarity is indifferent to the relay. In this form, the scheme has a significant drawback. There are, of course, more complex relays, with several groups of contacts in one housing - making, breaking, switching. Signal inversion and load control circuits. We connect to low-current transistor alarm outputs.

We connect the other end of the wire to pin 87A. How a 5-pin relay works and works

How to connect power windows via a 4-pin relay

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Once again, I am glad to welcome everyone who sees this post!

I'll say a few words about ESP. They worked well a long time ago when the car was purchased. Further, the usual symptoms in the form of loss of speed, up to complete failure. In the last days of this car’s life, only the driver’s ESP worked with tension, while the passenger one did not work from its button and showed minimal signs of life through the driver’s button. When I started restoring the car, after I started it, I checked the operation of the ESP. Both showed no signs of life.

So, in the end, as I wrote in the previous entry, I found the reason for their silence - there is no +12V in the ESP circuit. After supplying 12V to the circuit, the ESP started working. But they made money in a really funny way. Each ESP was turned on only from its own button, there were noticeable power drops. But the passenger was silent through the driver's button.

In general, I was tired of this eternal ESP sore, it was decided to close this issue once and for all by changing the power supply circuit of the ESP gearmotors through a relay.

The first thing you need is to draw up a work plan. I’ll say right away that it’s not a lot of work, but the advantages are obvious.

So, the circuit works according to the following logic: We have two 5-pin relays on each side, which are connected to the ESP gearmotor. The relays are normally closed to “-” in a quiet state. One power contact of the relay winding is connected constantly to 12V, which gives us the opportunity to control the relay by applying minus to the second contact of the winding. Each side of the button closes only one relay. Thus, when closing, the relay transmits “+” to the gearmotor, while the second relay still supplies “-“. When you press another position, the relay buttons change places, and we have the ESP working up and down. In this case, the buttons receive complete unloading from the power lines and supply only control “-” signals; wear of the button contacts will now in no way affect the speed of the ESP. According to this scheme, the operating speed of the passenger ESP now does not depend in any way on the driver's button.

Now the important thing is that when connected from the factory, the passenger button works through the driver button. This was done to protect against short circuits in the event that the driver and passenger press opposite modes. At the same time, the passenger ESP will not work if the driver or passenger button fails - they only work in pairs!

This scheme has built-in protection (which happened by itself). That is, if the driver and passenger press different modes, then both relays will close to “+” and nothing will happen - 100% protection. Another advantage is the independence of the operation of the passenger ESP in the event of a breakdown of one of the buttons, no matter whether it is the driver’s or the passenger’s. Button wear is kept to a minimum. Well, and the last thing - if the relays die, then buy new 5-pin relays and move on.

Phew, I wrote a lot of stuff. Enough praising yourself, let's move on to the practical part.

Of course, we need four 5-pin relays, which are sold at any auto parts store that sells electrical gadgets, and sockets for them. You also need 4 meters of wires with a cross section of 0.5 mm2.

The seller decided to sell me expensive 100A relays, noticed this later and did not change it, so much the better. I soldered one power wire of the relay winding to the wire to which “+” will be supplied. My paranoia is gaining momentum, so I took the remaining polyurethane sealant and filled the pads:

When you need to install ESP (electric windows) yourself, then, as always, on the Internet it is difficult to find correct and understandable diagrams for everyone. Having experience in radio electronics, I am laying out for everyone the correct and understandable diagrams for connecting an ESP, an intelligent glass closer Pandora DWM-210 (but it is better to install a Sheriff PWM-200), as well as simple closers only for raising the glass, installed in the wire gap on the positive side of the motor.

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The brightness of the LEDs decreases, such DRLs will no longer be able to fulfill their immediate task - to warn oncoming drivers from afar, and over time they will begin to flicker and fail. IMG: link And so. To do this, start the engine and, by moving the reed switch near the generator, achieve its activation and a stable glow of the DRL.

When fastening parts melt, the contacts shift and a sparking process is added, which further heats the contact point. When controlling a standard unit for unlocking, a button or reed switch is not needed; diode D2 is required. This leads to the following rule: to control a relay, an analog signal must be supplied through threshold devices, such as a Schmidt trigger, comparator, microcontroller, etc. Otherwise, the circuitry is duplicated. Relay contacts Usually a relay has 5 contacts, there are 4 contacts and 7 contacts, etc. Let's start with the simple and incorrect, and end with the complex and correct. On the cover there is a diagram of the legs. Contacts 85 and 86 are a coil. An electronic relay, or as it is also called a solid state relay, does not have this drawback, but it generates heat, since a transistor for a DC relay or a triac for an AC relay is used as a key. This seems complicated, but let's look at an example and everything will become clear.

Automotive relays: device, selection and testing

At 85 - mass. At 86 - plus from the horn, which goes to the standard horn. To switch large currents, tens and hundreds of amperes, relays of a different design than those described above are used.

Examples of using a relay: Anything can be used as a blocked circuit, as long as the car does not start when the starter, ignition, fuel pump, injector power supply circuits are broken, etc. If we need from a low-current negative alarm output to an alarm system, such outputs can be called differently and their purpose is also different: output for the 3rd ignition, output for opening the trunk, output for closing the windows, etc. It’s that simple. The four-pin relay A shown in the first photo uses a relay when the actuator is a starter, generator, fan, heated mirrors, horn, etc.

It is through these legs that the control current must pass: coming to one and flowing to ground from the other, the polarity is not important. However, you never know what problems may arise, for example, when installing additional equipment. To suppress the surge, a protective diode is switched on parallel to the relay winding. How a 4-pin relay works and is designed. How to connect an additional pump

Protection relay

Let's consider the design and principle of operation of electromagnetic current protection relays - maximum current relays. Electromagnetic relays, which have become very widespread, based on the design of the sensing element, are of the valve type and with a rotary armature.

Valve-type relays (see Fig. 2.15, b) are widely used as overcurrent relays. Designations in Fig. 2.15, b: 1 - excitation coil; 2 - yoke; 3 — valve (anchor); 4 - contact group.

The excitation coil of the RT current relay is connected in series to the controlled circuit (Fig. 2.17)

. When currents / in this circuit exceed permissible values, the force of attraction of the armature to the yoke overcomes the resistance of the spring and leads to the opening or closing of contacts P~ in the control circuit of another device (Fig. 2.17, a, b) - the KM device.

Opening the PT contacts in the KM apparatus (relay) circuit (Fig. 2.17, a) leads to the opening of the KM contacts in the controlled power circuit of the receiver, i.e., the current / breaking circuit (at the same time, the KML contacts that bypassed the “Start” button open). The disappearance of current in the excitation circuit of the current relay Рт leads again to the closure of its contacts Рт (the contacts of this relay are always closed in the absence of current in its winding), but now the excitation circuit of the KM relay is open, since the “Start” button is not turned on and the contacts KMj are open . To turn on the power supply circuit of the receiver, press the “Start” button again, the KM relay will operate and close its contacts KM}.

The “Start” button can then be released, since the KM relay excitation circuit continues to be closed through the KMR contacts shunting the “Start” button. Triggering of the RT relay in the diagram in Fig. 2.17, 6 leads to the closure of the initially open contacts Рт in the KM relay circuit.

The KM relay operates and opens its initially closed KM contacts, which bypassed the resistor R in the receiver power circuit.

In this case, a resistor with resistance R is connected in series with the receiver and thereby the value of the current in the circuit is limited. When the current drops to a normal value, the RT relay will “release” its RT contacts, the KM relay will turn off and the resistor R will be shunted again by the KM contacts.

Relays with a rotary armature are also used as current relays (Fig. 2.18), where an armature 3 made of a soft magnetic material is placed between the poles of the electromagnet /. In the absence of current in field winding 2, spring 4 holds the armature in such a position that contacts 5 and 6 are open, i.e., the control circuit is open. When the current in the excitation winding of the electromagnet reaches a value at which the force tending to turn the armature towards the yoke exceeds the counterforce of the spring, the armature will turn, contacts 5 and 6 will close, and the desired mode change will occur in the controlled circuit.

Another video about the operation of an electromagnetic relay:

The rotation of the driver associated with the spring causes a change in the counterforce of the spring 4 and, consequently, the relay is adjusted to the required operating current.

The operating current values are indicated on the scale. The same relay can be used to control the voltage value on any element. In this case, its field winding, obviously, should have a significantly larger number of turns of wire of smaller diameter compared to the current winding.

The receiver can be protected from an unacceptable decrease in voltage on it using a minimum voltage relay connected according to the diagram in Fig. 2.19.

If the source voltage corresponds to the required voltage, then the PH relay is activated and its initially open contacts PH close (positions 5 and 6 in Fig. 2.18). By pressing the “Start” button, the excitation circuit of relay K is closed and, through its contacts K, the receiver is connected to the source.

If the source voltage decreases below the permissible limit (which is determined by the setting of the relay Рн), then the counterforce of spring 4 (see Fig. 2.18) overcomes the force of attraction of armature 3 to yoke 1 and contacts 5, 6 open. The excitation current circuit of relay K (Fig. 2.19) opens and the receiver is disconnected from the source.

To protect electrical devices from overload currents, when long-term operation of the device in this mode can cause its failure due to unacceptable overheating, thermal relays are used.

The thermal relay (Fig. 2.20, a) consists of a bimetallic plate 2, which is located in the thermal field of the heater 7, connected in series with the controlled object (receiver), and contacts 4. If the controlled current is greater than permissible, then after some time the bimetallic plate 2 under the influence of excess heat from heater 1, it will bend, since its lower layer expands (elongates) more than the upper one. Plate 2 releases latch 3, which rotates under the action of a spring, and contacts 4 open. The thermal relay switching circuit is shown, for example, in Fig. 2.20, 6, where it is clear that when the thermal relay is triggered, its contacts break the power circuit of relay K and disconnect the receiver from the source. After cooling the bimetallic plate, the relay mechanically returns to its original position.

Control and automation relays (indicating and signaling relays). Electromechanical control relays are low-current devices designed to perform logical and measuring functions in control systems. To characterize the operation of the relay, a number of coefficients are introduced. If we consider the relay as a nonlinear element, the connection between the input /in and output /out quantities is shown in Fig. 2.21, then you can enter the return coefficient Kv as the ratio of the input value /p, at which the relay is activated, to the value of the same value /otp, at which the relay releases.

This coefficient depends on the ratio of the traction characteristic Fx (/в) of the relay (Fig. 2.22) and the characteristic Fnp(lB) of the opposing spring.

At the beginning of the relay actuation process at Iin = Ip, the gap is maximum (l at the beginning) and the force of attraction F1 of the armature to the yoke is slightly greater than the compression force Fnp of the opposing spring. At the end of the relay actuation process, the gap is minimal (/in con) and the force Fx of attraction of the armature to the yoke at the same current/n is already greater than the force F, which is necessary for reliable closure of the relay contacts. The relay will turn off when the current /in is equal to the current /out, i.e. when the force F= F2 becomes less than the force Fnp. The smaller the value DR = Fl - F2 (Fig. 2.22), the higher the return coefficient, the smaller the difference in the values of the operating current /p and the release current /otp. It is possible to ensure a high return coefficient only with relays with a small armature stroke, by reducing friction in the mechanism, and by using ferromagnetic materials with a narrow hysteresis loop. To increase the reliability of relay operation, it is necessary to ensure that the condition /in > /p is met. The required excess of current /in over the value 1p is called the safety factor.

Five-pin relay

We connect the alarm output to the contact

Imported relays under the Saturn and San Hold brands have proven themselves to be the most reliable and commercially available; relays from other manufacturers are also used. That is why a voltage stabilizer in the running lights connection circuit is extremely necessary. Contacts 30 and 86 are swapped.

As you already know, the use of DRLs in conjunction with other lighting devices is prohibited. Operation voltage: not less than 8.0V. Options for circuit solutions for connecting relays.

Otherwise, traffic police officers will issue you a fine, or even take your car to the impound lot. So what's going on? The magnitude of the control voltage and the voltage switched through the contacts can be different and do not depend on each other. Obviously, your DRLs will always work as long as the key is turned in the ignition, no matter what lighting you use.

Read additionally: To repair a broken wire in an electrical appliance, you need

The simplest scheme

It is important to note that if the relay has been operated for a long time when switching power circuits in extreme modes, then the spark that jumps when closing or opening the contacts creates carbon deposits between the contacts and because of this, the actuator may not work or will not work correctly. Case temperature The relay coil consumes about .5 watts of power, which is why its case can get quite hot during operation - this is not criminal. Everything that is not prohibited is permitted.

Now, if you try to start the car with the security switched on, contact 30 will open with contact 87A and will not allow the engine to start. I would like to emphasize that DRLs are intended to indicate your vehicle in front of other road users, and not to provide additional illumination of the roadway. Self-locking motor blocking circuit with self-locking. Accordingly, the other two terminals should show infinite resistance - these are our normally open working contacts. And so when at rest - the circuit is broken - that is, nothing comes to the plus of the fog lights, as soon as the ignition is turned on, the plus from the battery is switched on.

Illuminated toggle switch:

A toggle switch is basically a miniature mechanical switch or switch. It is used almost everywhere where electrical switching is required (control circuits in electronic and mechanical devices and devices). A very convenient type of toggle switches, often used in electronics, is a backlit toggle switch. Such a device not only connects and breaks a circuit, but also has a light bulb inside it that serves as an indicator of the supply of voltage to the circuit, Figure No. 1.

Figure No. 1 – Illuminated toggle switch and its circuit diagram.