Installation relay

What is a relay and how does it work? What types of relays are there? Where are relays used? And which relay suits your project best? Here you can learn more about switching and controlling electrical circuits. Installation relays are used in many different applications. You will find relays in domestic electrical installations, in electrical appliances, in commerce and industry, and in vehicles.

A look into history

The first relay was invented by the American J. Henry in 1831 and was based on the electromagnetic principle of operation. Henry used the relay in his university lab as a 'gimmick' to entertain his students. However, it was not yet possible to switch gears. The first switching relay was invented by Samuel Morse in 1837. Morse refined Henry's device and adapted it to transmit signals (the Morse code) down miles of wire. This was also the basis for the telegraph.

Did you know that the world's first computer was also built with only relays? It was a development by Konrad Zuse, which was presented in 1941. A lot has happened since then and relays are no longer used in modern computers. Nevertheless, the relay is still an important and popular component in electrical installations today. Think, for example, of switching on and off the lighting in the stairwell. The circuit works regardless of which floor you are on. However, there are numerous other areas of application. That is why different installation relays are also available in the eibabo® shop. Simply browse through our virtual catalogue. You will surely find some high-quality and inexpensive installation relays that arouse your interest.

Source: eibabo®, Eltako ER12-110-UC switching relayImage: Eltako ER12-110-UC switching relay

What are relays?

Relays are components within electrical installations of all kinds. They are mainly used as circuit breakers and control switches in electrical devices or are used as important components in many control processes. There are numerous types of relays, which differ in detail. The manufacturers develop the devices for special tasks and adjust the triggering characteristics accordingly. Relays that are often bought in this catalog are coupling relays, power relays, switching relays, interface relays, semiconductor relays and many more. The basic operating principle of a relay is to open and close circuits or contacts by reacting to electrical quantities such as current or voltage.

How are relays differentiated?

Relays are classified according to various criteria. These include:

  • the type of physical inputs to which the relay responds
  • the area of application that the relay assumes in control systems
  • the structure of the device design and the principle of operation
  • the switching capacity
  • the shape and size
  • and some others

 

A relay consists of three main elements:

  • entering / entering a value
  • the intermediate
  • of execution / actuation by actuator

 

If we look at the type of physical input variable, we distinguish between electrical, thermal, optical, mechanical, magnetic or acoustic relays.

 


Notice

Not all relays work with fixed physical quantities. Differential relays, for example, react to the difference in values. Polarized relays respond to a change in sign of a specific value.


 

The acquisition of the measurand is the primary element of the relay. This converts the input value into another physical quantity. The receiving element can have different designs depending on the purpose of the relay and the nature of the physical quantity. In the case of a latching relay or a voltage relay, the receiving element consists of an electromagnet. In the case of a pressure relay, this can be a membrane or bellows. The sensing element of a level relay is usually a float and so on.

The intermediate element compares the input value with the specified limit value of the device and, if it is exceeded, transmits an impulse to the executing actuator.

The actuator transmits the pulse from the relay to the working circuits. Each relay basically contains a control circuit and one or more operating circuits. Depending on the type of actuator, the relays are divided into contact relays and contactless relays. Contact relays act on the outgoing circuit with the help of electrical contacts. Their closed or open state allows either full closure or full mechanical break of the work circuit. Contactless relays act on the working circuit by a sudden change in parameters in the control circuit. This is achieved via resistance, capacitance, inductance or a change in voltage level or current level.

How does an installation relay work?

Depending on the requirement and application, relays are simple or complex. However, the basic functional principle does not differ significantly. In the center is the coil with an iron core. When current flows through the coil, an electric magnetic field builds up. A movable, ferromagnetic armature reacts to this magnetic field and is attracted. This change in position connects two contact springs with each other and the so-called working contacts in the relay close. In this case, the relay acts as a closer. In some designs, so-called break contacts are opened when the magnetic field is created. These are called openers. Combinations of openers and closers are also possible. These are changeover contacts or changeover contacts.

Already knew?

If the coil of a relay is suddenly de-energized, high voltage peaks can occur. Therefore, depending on the model, resistors or diodes are used to prevent these voltage peaks from flowing back into the control circuit. Sensitive components remain protected.


As soon as the coil no longer generates a magnetic field, the armature is returned to its original position by spring force. The make contacts are no longer closed and the break contacts are no longer open.

What are Solid State Relays?

More and more relay functions are currently being taken over by semiconductor circuits, so-called solid-state relays (SSR). A solid state relay is an electronic device that turns on and off a high power circuit with low voltages. There are no mechanically moving elements in this type of relay. The device consists of:

  • a sensor that responds to an input signal
  • a solid-state electronics with high-performance circuitry

 

Solid state relays can be used with both direct current and alternating current. With the help of thyristors and transistors it is possible to switch currents of several hundred amperes. Compared to electromechanical relays, semiconductor relays have a significantly higher switching speed. Solid-state relays are less suitable for switching under short-term overload conditions. Compared to electromechanical relays, solid state relays offer the following advantages:

  • smaller dimensions
  • high switching speeds
  • noiseless
  • powerful
  • more energy efficient
  • spark-free circuit
  • maintenance free
  • long lifetime
  • low sensitivity to adverse conditions

 

What should I look out for when buying an installation relay?

In the eibabo® shop there is a huge selection of different relays with numerous specifications. Choosing the right installation relay can be difficult. Before you buy, you should determine the function of your circuit and then define the task of the relay. Then select a suitable relay for your project. Decision criteria include:

  • What kind is the physical input quantity?
  • Will the device be subjected to vibration and shock?
  • Where will the installation take place?
  • Are dust, moisture or temperature fluctuations to be expected?
  • What is the switching voltage and the switching current?
  • Which current magnitudes and voltage magnitudes occur?
  • What is the expected switching frequency?
  • What requirements do I place on the durability of the relay?
  • Are special functions or additional programming required?

 

 


Notice:

When switching active and inductive loads, opening the circuit for the contacts is the most difficult. In this case, arcing occurs, which puts a lot of strain on the contacts.


 

The switching relays offered by eibabo® are high quality, inexpensive, versatile, reliable and universally applicable. The best-known manufacturers in our range are ABB, Doepke, Dold, Eaton, Eberle, Eltako, Finder, Hager, Jung, Schalk, Schneider Electric, Siemens and WAGO.

 

eibabo - technology store

 

Catalogue content:


In this eibabo® catalogue Devices for distribution board- / surface mounting > Installation relay you will find items from the following product groups:

Item overview:

  • AC contactor
  • AC voltage relay
  • Boiler relay
  • Built-in distributor device
  • Can relay
  • Coupling relay
  • DC contactor
  • Expansion module
  • Installation relay
  • Installation switching relay
  • Memory relay
  • Modular installation device
  • Power relay
  • Preset relay
  • Relay interface
  • Relay station
  • Switching relay
  • Universal voltage relay


from the following manufacturers:

Manufacturer overview catalogue Installation relay:

  • ABB
  • Doepke
  • Dold
  • Eaton
  • Eberle
  • Eltako
  • Finder
  • Hager
  • Jung
  • Schalk
  • Schneider Electric
  • Siemens
  • WAGO


 
What is a relay and how does it work? What types of relays are there? Where are relays used? And which relay suits your project best? Here you can learn more about switching and controlling... read more »
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Installation relays - You should know this before you buy

What is a relay and how does it work? What types of relays are there? Where are relays used? And which relay suits your project best? Here you can learn more about switching and controlling electrical circuits. Installation relays are used in many different applications. You will find relays in domestic electrical installations, in electrical appliances, in commerce and industry, and in vehicles.

A look into history

The first relay was invented by the American J. Henry in 1831 and was based on the electromagnetic principle of operation. Henry used the relay in his university lab as a 'gimmick' to entertain his students. However, it was not yet possible to switch gears. The first switching relay was invented by Samuel Morse in 1837. Morse refined Henry's device and adapted it to transmit signals (the Morse code) down miles of wire. This was also the basis for the telegraph.

Did you know that the world's first computer was also built with only relays? It was a development by Konrad Zuse, which was presented in 1941. A lot has happened since then and relays are no longer used in modern computers. Nevertheless, the relay is still an important and popular component in electrical installations today. Think, for example, of switching on and off the lighting in the stairwell. The circuit works regardless of which floor you are on. However, there are numerous other areas of application. That is why different installation relays are also available in the eibabo® shop. Simply browse through our virtual catalogue. You will surely find some high-quality and inexpensive installation relays that arouse your interest.

Source: eibabo®, Eltako ER12-110-UC switching relayImage: Eltako ER12-110-UC switching relay

What are relays?

Relays are components within electrical installations of all kinds. They are mainly used as circuit breakers and control switches in electrical devices or are used as important components in many control processes. There are numerous types of relays, which differ in detail. The manufacturers develop the devices for special tasks and adjust the triggering characteristics accordingly. Relays that are often bought in this catalog are coupling relays, power relays, switching relays, interface relays, semiconductor relays and many more. The basic operating principle of a relay is to open and close circuits or contacts by reacting to electrical quantities such as current or voltage.

How are relays differentiated?

Relays are classified according to various criteria. These include:

  • the type of physical inputs to which the relay responds
  • the area of application that the relay assumes in control systems
  • the structure of the device design and the principle of operation
  • the switching capacity
  • the shape and size
  • and some others

 

A relay consists of three main elements:

  • entering / entering a value
  • the intermediate
  • of execution / actuation by actuator

 

If we look at the type of physical input variable, we distinguish between electrical, thermal, optical, mechanical, magnetic or acoustic relays.

 


Notice

Not all relays work with fixed physical quantities. Differential relays, for example, react to the difference in values. Polarized relays respond to a change in sign of a specific value.


 

The acquisition of the measurand is the primary element of the relay. This converts the input value into another physical quantity. The receiving element can have different designs depending on the purpose of the relay and the nature of the physical quantity. In the case of a latching relay or a voltage relay, the receiving element consists of an electromagnet. In the case of a pressure relay, this can be a membrane or bellows. The sensing element of a level relay is usually a float and so on.

The intermediate element compares the input value with the specified limit value of the device and, if it is exceeded, transmits an impulse to the executing actuator.

The actuator transmits the pulse from the relay to the working circuits. Each relay basically contains a control circuit and one or more operating circuits. Depending on the type of actuator, the relays are divided into contact relays and contactless relays. Contact relays act on the outgoing circuit with the help of electrical contacts. Their closed or open state allows either full closure or full mechanical break of the work circuit. Contactless relays act on the working circuit by a sudden change in parameters in the control circuit. This is achieved via resistance, capacitance, inductance or a change in voltage level or current level.

How does an installation relay work?

Depending on the requirement and application, relays are simple or complex. However, the basic functional principle does not differ significantly. In the center is the coil with an iron core. When current flows through the coil, an electric magnetic field builds up. A movable, ferromagnetic armature reacts to this magnetic field and is attracted. This change in position connects two contact springs with each other and the so-called working contacts in the relay close. In this case, the relay acts as a closer. In some designs, so-called break contacts are opened when the magnetic field is created. These are called openers. Combinations of openers and closers are also possible. These are changeover contacts or changeover contacts.

Already knew?

If the coil of a relay is suddenly de-energized, high voltage peaks can occur. Therefore, depending on the model, resistors or diodes are used to prevent these voltage peaks from flowing back into the control circuit. Sensitive components remain protected.


As soon as the coil no longer generates a magnetic field, the armature is returned to its original position by spring force. The make contacts are no longer closed and the break contacts are no longer open.

What are Solid State Relays?

More and more relay functions are currently being taken over by semiconductor circuits, so-called solid-state relays (SSR). A solid state relay is an electronic device that turns on and off a high power circuit with low voltages. There are no mechanically moving elements in this type of relay. The device consists of:

  • a sensor that responds to an input signal
  • a solid-state electronics with high-performance circuitry

 

Solid state relays can be used with both direct current and alternating current. With the help of thyristors and transistors it is possible to switch currents of several hundred amperes. Compared to electromechanical relays, semiconductor relays have a significantly higher switching speed. Solid-state relays are less suitable for switching under short-term overload conditions. Compared to electromechanical relays, solid state relays offer the following advantages:

  • smaller dimensions
  • high switching speeds
  • noiseless
  • powerful
  • more energy efficient
  • spark-free circuit
  • maintenance free
  • long lifetime
  • low sensitivity to adverse conditions

 

What should I look out for when buying an installation relay?

In the eibabo® shop there is a huge selection of different relays with numerous specifications. Choosing the right installation relay can be difficult. Before you buy, you should determine the function of your circuit and then define the task of the relay. Then select a suitable relay for your project. Decision criteria include:

  • What kind is the physical input quantity?
  • Will the device be subjected to vibration and shock?
  • Where will the installation take place?
  • Are dust, moisture or temperature fluctuations to be expected?
  • What is the switching voltage and the switching current?
  • Which current magnitudes and voltage magnitudes occur?
  • What is the expected switching frequency?
  • What requirements do I place on the durability of the relay?
  • Are special functions or additional programming required?

 

 


Notice:

When switching active and inductive loads, opening the circuit for the contacts is the most difficult. In this case, arcing occurs, which puts a lot of strain on the contacts.


 

The switching relays offered by eibabo® are high quality, inexpensive, versatile, reliable and universally applicable. The best-known manufacturers in our range are ABB, Doepke, Dold, Eaton, Eberle, Eltako, Finder, Hager, Jung, Schalk, Schneider Electric, Siemens and WAGO.

 

eibabo - technology store

 

Catalogue content:


In this eibabo® catalogue Devices for distribution board- / surface mounting > Installation relay you will find items from the following product groups:

Item overview:

  • AC contactor
  • AC voltage relay
  • Boiler relay
  • Built-in distributor device
  • Can relay
  • Coupling relay
  • DC contactor
  • Expansion module
  • Installation relay
  • Installation switching relay
  • Memory relay
  • Modular installation device
  • Power relay
  • Preset relay
  • Relay interface
  • Relay station
  • Switching relay
  • Universal voltage relay


from the following manufacturers:

Manufacturer overview catalogue Installation relay:

  • ABB
  • Doepke
  • Dold
  • Eaton
  • Eberle
  • Eltako
  • Finder
  • Hager
  • Jung
  • Schalk
  • Schneider Electric
  • Siemens
  • WAGO
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