Security alarm systems types types. Types of security detectors: classification and principle of operation. Alarms connected to a telephone line

13.11.2019

New Year's holidays are just around the corner. Every year before the New Year holidays, a grandiose season of sales and unusual events begins. For everyone who decided not to miss the opportunity to purchase during the New Year holidays, we have prepared this review.

Even with a strong door and reliable locks, it is impossible to be completely confident in the safety of your own home, especially during the long New Year holidays. To increase the level of protection for yourself and your property to the maximum, you need or. All modern systems operate on a similar principle, but differ in the method of transmitting information, the number and type of sensors and some other features. To understand what is best in each specific case, you need to figure out what types burglar alarm exist and how they work.

STRUCTURE AND PRINCIPLE OF OPERATION OF THE SECURITY ALARM

Home security alarms differ in the method of transmitting information and the recipient who receives this information. Otherwise, their operating principle is similar and is based on the interaction of the main elements of the system:
- a set of sensors and gauges different principle actions;
- control panel;
- executive systems, which include sound and light warning systems, as well as equipment that transmits signals to the security console and/or the owner’s telephone;
- keyboards and other control devices – . Equipped with buttons, display, fingerprint, voice identifier, etc.;
- power unit;
- connecting wires that may be missing when using a wireless alarm system.

Sensors located in different parts of an apartment or private house react to unauthorized entry and send a signal to the control panel. It receives them, processes them and transmits the generated signal to warning and signal transmission devices. Information within the system can be transmitted via wires or radio channels, and it is received by the security company and the apartment owner using networks mobile communications, via radio or via the Internet.

The most important role in the security alarm system is played by sensors - they are the first to receive the blow and are required to notice any illegal movement in the apartment. Sensors are divided into two types:
- security. These are the main sensors that are necessary to detect the entry of uninvited guests into the house;
- detector sensors. They are usually present and can warn the owner about water leaks, gas leaks, report fire, smoke and carbon monoxide, lack of electricity, etc.

Security sensors, which are the basis of alarm systems, can be different types:
- magnetic contact sensors are located near windows and doors and respond to their opening;
- Passive infrared detectors are among the most popular sensors. They work on the principle of detecting sudden changes in temperature environment. If an attacker passes into the field of action of the sensor, the latter records a sharp increase in temperature at a certain point and an equally sharp decrease. Such fluctuations cause the detector to trip. Detectors of this type are placed on the ceiling or wall; their angle of action can be different: there are 360-degree sensors, and there are point sensors;
- ultrasonic sensors operate on the principle of emitting ultrasonic waves with a frequency of 15-75 kHz. They are emitted from a source, reflected from the hard surface of the wall and returned back. If there is no one in the protected area, the wave will return with the same frequency. The human body is able to absorb part of the energy by changing the frequency of the waves; the work is based on the Doppler principle. When the sensor detects that the signal has not returned as expected, it transmits alarm information. It is not difficult to deceive such sensors, which is why they are considered obsolete;
- microwave sensors allow you to detect the presence of an uninvited guest by passing microwaves from the transmitter to the receiver. They can be in one building, if we are talking about an apartment or house, or in different buildings, when the area in front of the house is protected. To reduce the number of false alarms, such sensors often work in tandem with passive infrared;
- photoelectric sensors allow you to recognize the movement of a thief using visible or infrared light, which are emitted by devices on the wall. If an intruder passes through the beam, an alarm will sound. It is not difficult to bypass such sensors, so it is recommended to install them chaotically, in a checkerboard pattern, to create a radial fence;
- Seismic sensors are used to detect glass breakage. They are usually attached to glass or window frame. When the glass breaks, shock frequencies of 3-5 kHz are emitted, which are recorded by the sensor.

By installing several types of sensors in an apartment, you increase confidence that not a single step of an intruder will go unnoticed. When a door or window is opened, the integrity of a glass or wall is broken, or movement around the apartment, a corresponding signal will be sent to the control point. Typically, sensors and control panels are manufactured on the principle of complete interchangeability, which means that, if necessary, the security alarm system can be expanded. The type and number of sensors are selected depending on the configuration and size of the apartment. A large number of sensors is not always good, since they can duplicate each other. That’s why it’s better to turn to specialists to properly organize a home security system.

You can configure the alarm so that, in addition to notifying the owner and/or security company, activating sirens and emergency lighting, it will block Entrance door or the smoke generator has been activated.
The signal is transmitted from sensors to the control panel and warning devices wirelessly via radio channels or wired highways.

WIRED AND WIRELESS HOME SECURITY ALARM

Both systems are used today equally successfully, but wireless ones are still confidently winning the palm.

Wired systems have the following advantages:
- more low price arrangement;
- high signal quality;
- high reliability if installed correctly.

The main disadvantage of such a system is the lengthy and labor-intensive installation, the presence of cables that can spoil the interior, so it is recommended to install a wired alarm system at the renovation stage. Moreover, the wires must be installed as discreetly as possible, otherwise there is a risk that an attacker will violate their integrity and disable the entire alarm system.

Wireless alarm systems are increasingly being used due to the following advantages:
- quick installation;
- no wires;
- the ability to move sensors or expand the system with new sensors.

Among the disadvantages are the higher cost and the risk that the radio signal can be jammed, so it is better to expand the system with elements that would prevent jamming of the radio signal. Wireless alarm systems do not always work reliably, and the distance between the security sensors and the control panel should not be too large.

The disadvantages of wireless systems also include the lack of constant monitoring of the communication channel. Since it is not always possible to monitor the current status and performance of the sensor, you cannot be completely sure that dangerous situation notification will be sent. On the other hand, it cannot be said that wireless alarms are outright unreliable - they simply can fail in conditions of strong electromagnetic interference.

You also need to be prepared that wireless systems require replacement of batteries (batteries or accumulators). It’s better not to skimp on batteries, and most detectors have a low-battery alert option.

PRINCIPLE OF SECURITY ALARM ORGANIZATION

Depending on who and how receives information about penetration into the apartment, alarms can be divided into:
- autonomous;
- control rooms.

An autonomous system is the simplest alarm option. When the sensors are triggered, a sound (about 120 dB) or light signal is activated, which has a psychological effect on the thief and attracts the attention of neighbors, and a message can be sent to the owner. The security service does not receive a signal; the owner of the apartment takes full responsibility. Among the advantages of such systems are low cost and ease of installation. Autonomous alarms are great for apartment buildings, but is not very effective for a private house, especially if it is located in a remote area; in addition, it has high percent false positives.

The remote alarm provides for the transmission of information about a break-in to the remote control of a public or private security agency, but does not eliminate the ability to use sound signals. Having received a signal about a robbery, security company employees must arrive at the scene as quickly as possible. This system allows us to talk about the most effective protection to date. Its cost is no longer so high as to give up the protection of your property, and quite often, installation and connection can be done inexpensively at a promotional price, and the subscription fee to a security company is almost equal to the cost of a couple of cups of coffee.

Out of distrust, many are afraid that while they are away from home, security company employees will be able to enter the apartment. There is no need to be afraid of this for a number of reasons: firstly, the unlock code is known only to family members, and secondly, all unlocking situations are recorded in a protocol on the remote control and duplicated in your smartphone. By the way, it also reacts when someone cuts the cable, if the system uses this communication channel to transmit information.

In fact, any system can be turned into a GSM alarm system by retrofitting it with the appropriate module, leaving all existing elements in place. In this context, it is most advantageous to choose a control panel with an existing cellular transmitter.

GSM HOME ALARM

A security alarm system that transmits information to owners and a security company via cellular networks is one of the most modern and optimal options for organizing the protection of your own home. A separate or integrated GSM module in the control unit is equipped with a SIM card of one of the operators, with the help of which information is transmitted. It is recommended to use two SIM cards from different operators to ensure maximum system reliability and stability.

In case of penetration into an apartment, information about the incident is transmitted to the owner, security structure and other trusted persons, and the data can be broadcast in the form of SMS, MMS with a photo or a call. Sirens and flashing lights may be activated along with the information being sent.

This type of security alarm system may include a panic button. This is a kind of sensor, but it is triggered if a person presses it. If you are in an apartment and feel something is wrong, you just need to press a button for the security service to arrive (when a remote alarm is used).

GSM alarms are often enhanced with microphones to visualize what is happening. Sometimes they include sensors for gas leaks and water leaks, but this is no longer a security alarm in pure form. Signaling capabilities through use cellular communication are expanding significantly, but at the same time the cost of the security system itself is increasing.

LARGE MANUFACTURERS OF SECURITY ALARM EQUIPMENT

It is difficult to argue with the fact that the reliability of the home alarm system depends on the quality of each individual element and the interaction between them. There are a lot of offers on the market for such equipment, there are both foreign and domestic systems, and you can install a standard set or create a security system at your own discretion, equipping it with the required number of sensors of a certain type.

When purchasing, it is better to focus on the products of large security companies with sufficient experience and their own remote control.

It is better to entrust the installation of equipment to professionals, but if you have minimal knowledge, then you can install a simple autonomous security system yourself. When choosing a security company that will receive alerts from the alarm system, pay attention to

It’s probably no secret to anyone that those who like to profit from other people’s goods have met (and still meet) always and everywhere in huge numbers. But modern technologies have stepped so far forward that an attacker, even if he knew at least a thousand ways to penetrate private property, would find it quite difficult to carry out his plan. This is due to the fact that in Lately Comprehensive security solutions have appeared that combine quite a lot of capabilities. This is a security system for a private home, office, bank, enterprise, etc. Let's consider the most basic aspects regarding the functioning of such devices.

Security systems for a private home: types and general concepts

So, what is such a system? Here it is worth clearly distinguishing the complexity of combining the total control components, monitoring capabilities for uninvited guests, types of notification, as well as options for connecting equipment.

Today, there are three main types of such systems:

• autonomous systems " Smart House»;
• wired systems;
• wireless (GSM security systems for a private home or office).

Let's briefly look at each type. But first, a few words about the equipment used.

Equipment used

If you look at it, any security system for a private home, office or enterprise, depending on the degree of complexity and the functions assigned to it, must include several mandatory components: a visual surveillance system or the use of motion sensors, a warning system for an attempted illegal intrusion (sound or light alarm, instant SMS sending to the owner of the house or office), the ability to block an intruder if he has already entered the premises, a central control panel and an uninterruptible power supply in case of a power outage.

It goes without saying that in the simplest case, most only motion sensors are installed. Among their types are the following:

• passive infrared sensors, reacting to thermal radiation;
• beam infrared sensors with a reaction to the presence of a moving object in the area where the beams intersect;
• sensors that operate on the basis of the reflection of radio waves sent to a moving object (similar to the reaction of bats);
• contact magnetic sensors that are triggered when doors are opened;
• vibration sensors that detect the slightest vibration of the surface on which it is installed (floor, walls, etc.);
• sensors that detect damage to glass in windows or double-glazed windows;
• capacitive sensors for metal, triggered when the parameters of the magnetic field around them change;
• combined systems that include, in addition to the above, functions for detecting gas or water leaks.

Smart Home Systems

Perhaps today, Smart Home systems are the best. With their integrated installation, this includes not only a primitive alarm system for a private home. In this case, several systems are combined into one. That is, the security function is combined with autonomous control of all devices in the house or cottage.

Again, depending on the complexity, such systems may have video cameras, motion sensors, and controls for gas or water appliances, and are used different ways notifications when one or another occurs unpleasant situation. As expected, such systems are completely autonomous, but if desired, their owners can connect them to specialized security services. After receiving an alarm signal, a special team goes to the scene to understand the situation and, if necessary, take appropriate measures.

The only drawback is the very high cost of both the system itself and the costs of paying for the services of a security company.

Wired security systems

A wired security system for a private home is the simplest and cheapest. Among the advantages of such systems, judging by numerous reviews from their owners, is that the sensors used do not need to constantly change batteries or charge battery packs.

Naturally, in case of emergency, provision must be made for installing a special uninterruptible power supply (similar to how this is done for computers). And it goes without saying that any sensors and cameras can be combined into one system. But here it all depends on the needs of the home owner.

Wireless GSM alarm

Using wires for connections often causes legitimate difficulties. What if the house is renovated? After all, to lay cables, for example, in the walls, you will have to redo everything all over again, and this is a cost, and a considerable one at that. That is why many actively use wireless security systems for a private home or office.

There are two worth noting here important features. Firstly, all sensors or IP cameras are connected to the control unit either via Wi-Fi or a specific radio frequency. Secondly, (why they are called GSM systems) to a pre-registered number or several numbers mobile phones an SMS message is sent in case of an emergency or even a video image is broadcast. But such systems are an order of magnitude higher than wired ones.

Brief overview of the best manufacturers

As for everything that is now offered to the market, we can highlight several of the most popular manufacturers, both foreign and domestic:

• Visonic;
• Optex;
• Texecom;
• LifeSOS;
• Jablotron;
• Netatmo;
• Nest;
• Canary;
• Honeywell;
• Piper;
• Samsung;
• Kodak;
• Ademco;
• "Guardian";
• "Avalanche";
• "Granite", etc.

As many have probably already noticed, the list includes Samsung and Kodak. Their systems are mostly focused exclusively on video surveillance using a high-resolution camera with a rotation angle of almost 360 degrees.

It is worth mentioning separately about Honeywell products. Essentially it's not the whole system, but only the main unit (Honeywell Tuxedo Touch), with the help of which monitoring, alarms, and the functioning of heating, gas and water supply systems are carried out.

The products of other manufacturers are aimed at both private consumers and entire enterprises. Among the presented products you can find quite a lot of solutions by type of system.

Security systems for a private home: reviews

But here's what's interesting. Despite the high quality of their products, Western manufacturers, for example, are not particularly popular in Russia. Feedback from owners shows that domestic systems look much more preferable in terms of operation. First and most importantly, they are designed to operate in post-Soviet power grids with a voltage of 220 V (and not 230 or 210 as in Europe or America). In addition, such systems do not turn off during significant voltage surges (in our country +/- 10-15%, in the West - +/- 5% of the nominal value).

On the other hand, systems from Russian developers feel great in conditions of low temperatures or high humidity, although in most cases they are somewhat inferior to foreign analogues in terms of functionality, as users note.

It is believed that one of the most interesting is an imported security system for a private home model range Vista from Ademco. In part, it duplicates the products of the Canadian company DSC, but its main feature is the possibility of almost unlimited addition of new equipment and integration, say, even with lawn watering systems or fire alarms.

Among foreign systems, users also note the products of the Israeli company Visonic, which has proven itself to be excellent when installed in cottage villages.

Professional security systems for businesses

The system, when compared with the private sector, is quite complex both in terms of the equipment used and in terms of management.

Based on the fact that production area can be quite large; the most popular are hybrid systems from such giants as AXIS COMMUNICATIONS, ASSA ABLOY, BOSCH SECURITY SYSTEMS, etc.

Their solutions in some cases involve the installation of additional repeaters to amplify the signal of the sensors, which makes it possible to increase the distance between them up to 500 m. In addition, it is possible to use not one, but several control panels (units) or special key fobs that allow you to give an alarm signal manually from any place if the main system does not work for any reason.

How to make a security system yourself and is it worth it?

In general, making security systems for a private home with your own hands is not so difficult. But the essence of the issue comes down to choosing the necessary basic and related equipment and connecting it correctly.

Of course, you can order services from a specialized company, but it’s easier to buy everything yourself. It will cost much less. As for the connection, anyone who knows the plus from the minus can connect the devices and the control unit.

Some craftsmen, however, try to solder circuits themselves, but without professional equipment and fine tuning is still indispensable here. So it’s better to buy all the devices separately. For example, the cost of the simplest system of two sensors will cost an average of 100-120 dollars, systems a little more complex for a private home - already 300-700 dollars, but conversion into a Smart Home complex can amount to tens and hundreds of thousands of dollars, so What do you think, is all this necessary if such a system is not fully involved.

Protecting your property is one of the main tasks for its owners. To implement it, many different means and devices have been developed and offered on the consumer market that make it possible to prevent entry into a protected facility, scare away burglars, and notify the owner and the relevant services about the incident. Depending on the chosen protection option, you can opt for mechanical or electronic means of protection and security. Mechanical devices only make it a little more difficult for an attacker to penetrate, but do not provide more effective protection of the protected object. For such purposes it would be more effective different kinds security alarms, which are distinguished by much greater functionality and capabilities for protecting real estate.

Purpose

The main task of the currently available types of alarm systems is to promptly warn property owners and security services about attempts to enter a protected facility.

This goal can be achieved only with the correct choice of security alarm for a specific object. The types of security alarms offered to the consumer can be autonomous or active. In the first case security equipment allows you to scare away robbers and notify others about the danger with the help of sound and light-emitting security devices. The second option is more effective, since it involves transmitting an alarm signal to the central console of security companies or to the mobile devices of the property owner.

Main types and types of security alarms

To ensure the protection of your property, you can use the following types of home alarms.

The use of this security system involves the installation of security sensors at the site (movement, opening/closing, window breaking, etc.), which are connected to the central alarm control panel. Sound sirens and light-emitting elements are connected to the remote control as actuators.

If one of the sensors is triggered, the signal is sent to the electronic unit, which activates executive systems that warn of intrusion into the facility. The alarm can be turned off/on using a code panel on the central unit or a remote key fob.

• GSM systems

Modern types of security include innovative developments in the field of ensuring property security - this is. These systems provide for the installation at a protected site, in addition to the usual set of devices that an autonomous alarm system has, also a GSM transmitting module, which is built-in or connected to the central alarm unit.

If at least one of the security sensors is triggered, this alarm, in addition to turning on sound sirens and lighting devices, transmits an alarm signal to the telephone numbers of property owners, which are entered into its memory.

• Alarms connected via telephone line

These systems are similar in principle to the previous ones. The difference is that they communicate with the owner not through a GSM connection, but through a regular telephone line. If a threat occurs in one of the zones, an alarm signal, in the form of an audio message, is transmitted by dialing to pre-programmed telephone numbers.

Most effective types security systems are those that have the ability to transmit an alarm signal to the central consoles of departmental security services. Such systems include a special electronic unit, which, when the sensors are triggered, transmits an alarm signal to the security service console. The channels through which the alarm signal is sent can be regular telephone lines, radio frequency communications or GSM channels. To ensure greater alarm resiliency, several signal transmission channels to the security console can be used in parallel.

What to look for when choosing?

Before installing an alarm, many people wonder how to choose an alarm for their home and what to pay attention to. There are several basic criteria.

1. You need to decide on the type of security system - autonomous or active.
2. You should select the type of sensor connection - it can be wired or using a radio frequency channel.
3. If there are pets in the house, you need to choose sensors that do not react to their presence - this will eliminate cases of false alarms.
4. It is important to decide on the number and type of security lines that the security system should provide.
5. The alarm power system must provide for the possibility of its operation in autonomous mode - this will protect the facility even when the electricity is lost.

Note!

If you plan to further expand the configuration of the security system, you need to choose equipment that provides for the connection of additional sensors, actuators, and expansion modules.

Conclusion

Due to the fact that they are represented on the consumer market different types security alarms, which differ in their functionality and price category, everyone can choose best option to protect your property. When choosing an alarm, it is important to pay attention to its functionality, not the price. After all, saving in such a matter is unlikely to be appropriate, given that the alarm system will be protected by much more expensive things than its cost. Therefore, you should focus on the quality of protection, and not on the price category.

Video. Which alarm system to choose for an apartment

Classification of security and fire systems by type and type can be made according to a number of different parameters. The most obvious one is purpose. There are three large groups here:

TYPES OF SECURITY ALARMS

Security systems can also use various types of sensors, which can be wired or wireless, and differ in the way they detect intrusion and process the signal. The principles of constructing security systems may vary depending on their purpose: for a house and cottage, apartment, objects of various organizational and legal forms.

An elementary option is an alarm system consisting of one motion sensor with a built-in GSM module. Despite its apparent simplicity, this type of security is quite reliable and is well suited for protecting small country houses.

In general, the security alarm system uses several types of detectors, which are classified according to their purpose and principle of operation. To ensure reliable security, sensors are used to monitor:

• opening windows and doors;
• breaking of glazed surfaces;
• breach of walls, partitions and ceilings.

The listed equipment is used to protect the perimeter of the premises. In addition, there is a group of sensors that detect movement inside or on the approaches to the object. The selection of specific types of detectors is made taking into account the individual characteristics of the object to be protected.

Laboratory work No. 7

Subject: Control and protection equipment for automation circuits.

Job title: Study of the design and operation of signaling equipment.

Goal of the work:

1. Study the device, principle of operation and technical specifications alarm devices.

2. Learn to determine the parameters of alarm devices.

Acquired skills and abilities:

1. Learn to collect electrical circuits with the participation of alarm devices.

General information

To ensure the normal operation of any devices, it is necessary to timely and reliably notify service personnel about the status, operating modes and positions of individual mechanisms, drives, components, and progress technological process and the state of its parameters, about the achievement of the minimum and maximum permissible values ​​of the measured and controlled quantities of the control object, about the danger of breakdowns, accidents, about the achievement of specified or limit values operating parameters. To perform these functions, various devices and light, sound and visual signaling devices are used.

Types of alarms

Depending on the purpose, the following alarm systems are distinguished: information (positions), warning, emergency.

Position alarm informs maintenance personnel about the condition and position of electrical devices and circuits. Position signaling is performed for mechanisms that have two or more working positions. The most common two structures for constructing circuits for signaling the position (state) of technological mechanisms:

· signaling circuits combined with control circuits;

· signaling circuits with power supply independent of control circuits for a group of technological mechanisms for the same or different purposes.

Signaling circuits combined with control circuits are usually implemented if effective area boards and consoles allows you to use signaling equipment without limiting its size and allowing direct feeding from control circuits. Signaling the position (state) of technological mechanisms in such schemes can be carried out by one or two light signals.

For example, the electric motor is on or off, working or faulty, etc. Such signaling is usually carried out using block contacts of magnetic starters and alarm lamps switched on through them, or alarm lamps switched on in parallel to the coil of the magnetic starter. It should be noted that both methods of signaling the operation of electric motors are indirect, so the possibility of receiving false signals cannot be excluded. So, for example, a magnetic starter can turn on, close its power and blocking contacts, but the electric motor, as a result of a phase failure or some other reason, cannot start. If the thermal protection does not disconnect the motor from the mains, the operator will see a signal that the motor is running, when in reality it may not be running. A direct signal about the operation of the electric motor could be a signal from the speed relay (speed control device - UKS) of rotation of the electric motor. However, this leads to the complexity and cost of the scheme, so in practice they use indirect signaling methods. If we take into account that the probability of the occurrence of the discrepancy described above (no rotation of the electric motor when the magnetic starter) is very small, then the admissibility of using indirect signaling schemes will become obvious. Signaling the positions of dampers, valves, etc. produced from limit switches and devices (instruments) designed to perform the same functions. The limit switch is triggered at certain positions of gates, flaps, gate valves, etc. Alarm devices are switched on directly through limit switches or intermediate relays.

Warning alarm notifies about the upcoming launch of an automatic production line or an automated unit, ensuring the safety of work, and also informs the operating personnel about the deviation of controlled values ​​from the specified values. With centralized control of units, installations, production lines, etc. the operator does not see the result of his influence on the machines and judges their activation by light signals and instruments. To prevent injuries to people in the room, when the machines are started centrally, a sound signal (siren, etc.) is sounded. To prevent machines from starting without a warning signal, special circuits are used.

Alarm informs about shutdowns of the most important objects, or deviation of the technological process from the specified course, that the controlled value has reached the maximum permissible value. The alarm requires immediate operator intervention; it will sound until the operator corrects the abnormal operation.

Warning and emergency alarms, intended to notify operating personnel about a violation of the normal course of the process, are carried out by a steady or flashing light and are usually accompanied by a sound signal. The most common alarm schemes are those with a central sound signal. They make it possible to receive a new sound signal before the contacts that caused the previous signal to appear are opened.

Depending on the method of presentation, alarms are divided into light (signal lamps and displays), sound (sirens, beeps and bells) and visual.

When performing alarms, as a rule, they combine sound signals, sound and light signals, use different signal colors, blinking, burning and extinguishing states, etc. The form of the alarm depends on where it is used. The nature of the production facility also influences the choice of one or another type of alarm (the presence of production noise, dust, the distance of machines from control panels, the size of the room, etc.) When signaling, the choice of one color or another, characterizing the normal operating mode, is determined in each specific case based on control conditions, alarm monitoring and technological process features. The normal position of the mechanisms is usually indicated by green color, emergency condition or stop - red, warning - yellow.

Light signaling carried out using various signaling equipment: displays, banners, semaphores and illuminated mnemonic diagrams placed on consoles and control panels. Using signal lamps and fittings with caps of different colors, it is possible to communicate the necessary information by changing the operating mode of the lamp: the light signal can be reproduced with a steady or flashing light, as well as with the lamps glowing at partial incandescence.

In addition to lamps for light signaling, LEDs are widely used, having the most various designs and glowing in different colors when flowing through them electric current small size.

Light signaling using lamps is a simple and reliable means of warning. Signal lamps installed in special fittings are used to signal the operation of machines and units, the presence of voltage in the supply network and control panel, etc. For reliable operation of lamps, they are usually switched on through additional resistances that reduce the heat. Signal lamps are covered with glass caps (lenses) of different colors; in accordance with the color of the lens, the signal can have one or another meaning. For example, green is a normal state, yellow- warning signal, red color - emergency condition, White color- various production signals.

The combination of several light signals forms a light display; its capabilities are much wider than those of a signal lamp. An inscription can be applied to the glass, which stands out clearly when the display is turned on. Entire commands are transmitted this way. Structurally, the board differs from conventional signal fittings in its external design.

Sound alarm. In some cases (especially for emergency situations) light signaling is not enough to quickly alert maintenance personnel. To do this, use sound signaling equipment (bells, buzzers and sirens) included in the circuit of signal contacts of the control circuit. Disabling the audible alarm is usually done manually after taking appropriate measures. Some schemes provide automatic shutdown sound alarm after appropriate switching in control circuits or from a special time relay.

Sound alarm devices are characterized by their simplicity of design and reliability. They are used to attract the attention of service personnel to changes occurring in controlled systems and to call personnel to a specific location. Sound equipment includes: loud bells used for warning signals about the remote start of production production systems or sections thereof, as well as horns, howlers and sirens for alarm about stopping machines and mechanisms, about dangerous overfilling of bins and other violations of the technological process.

Conventional electric bells, loud bells, and alarm sirens are used as sound alarm devices. To receive weak sound signals, you can use buzzer elements used in communications technology.

The choice of the type of sound alarm equipment is made taking into account the importance of the objects, the size and nature of the room and the service conditions.

Visual alarm. In some cases, signaling can be performed using special indicator blinker relays that change their state when a certain amount of current flows through their coil. Return to the initial state is carried out manually, by cocking the indicator rotation mechanism or by pressing the indicator button (depending on the design of the relay).

Combined alarm. In addition to those listed, combined-action signaling devices are used in practice, for example, bells with a built-in signal lamp.