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Comprehensive Guide to Switches

What is a switch?


A switch is defined as a mechanical, electrical, electronic, or optical device that is used to open or close a circuit to start or stop the electricity flow when it is pressed up or down. The inner part of the switch acts as a conductor, and the outer part of the switch acts as an insulator. A switch is used to control the continuity between the two points. A switch is a binary device because it is either ON completely (closed) or OFF completely (open). A switch will respond to a force that is applied externally to change an electrical signal mechanically.

A switch is used to turn on or turn off equipment like TVs, lights, washing machines, mixers, grinders, and fans.



Switch
Switch


The switch is off when the circuit is open, and as a result, there will be no current flow in the electrical circuit.

The switch is on when the circuit is closed, and as a result, there will be current flow in the electrical circuit.



Switch Symbol
Switch Symbol


Types of switches


There are various types of switches. Based on their size, robustness, environmental resistance, and various other characteristics, switches are divided into various types.


Switches in industrial equipment and consumer and commercial devices


  • Basic switches

  • Thumb-wheel switches

  • Push-button switches


Switches in consumer and commercial devices


  • Tactile switches

  • Miniature detection switches

  • Rocker switches

  • Toggle switches

  • DIP Switches


Switches in industrial equipment


  • Limit switches


Classification of switches


Detection Switches


Basic switches, miniature detection switches, and limit switches come under detection switches. It is used to detect the position of the object.


Manual Switches


Tactile switches, rocker switches, toggle switches, and push-button switches come under manual switches. It is allowing workers to make inputs to the device or the equipment.


Setting Switches


DIP switches and thumb-wheel switches come under Setting switches. It is used to set up operations on equipment.


Difference between an electrical switch and a mechanical switch


Electrical switches work under the influence of semiconductors, whereas mechanical switches require manual contact with the switch for the operation of the electrical circuit.


Types of mechanical switches


Mechanical switches are classified depending on the poles and throws.

  • The pole is the number of input circuits available to the switch.

  • Throw is the number of paths for the current flow that are available to the switch.


Mechanical switches are divided into the following types, namely:

  • SPST: single pole single throw

  • SPDT: single-pole double throw

  • DPST: double pole single throw

  • DPDT: double pole double throw

  • 2 poles, 6 throws

  • Momentary control switch


The momentary control switch is further classified into five types, namely,

  • Push-button switch

  • Pressure switch

  • Temperature switch

  • Toggle switch

  • Rotary switch


SPST (single pole single throw)


It is the simplest switch type and has two terminals. One of the terminals is an input terminal called a pole, and the other is an output terminal called a throw. This SPST is used in either a single loop or one closed path.


SPST (single pole single throw)
SPST (single pole single throw)

SPDT (single pole double throw)


It contains one input terminal and two output terminals. This type of switch is commonly used as a selector switch, i.e., current can be supplied to two loops.


SPDT (single pole double throw)
SPDT (single pole double throw)

DPST (double pole single throw)


It controls two circuits simultaneously. It contains two input terminals and two output terminals. In such types of electrical circuits, two switches are connected to a single lever and operate simultaneously.




DPST (double pole single throw)
DPST (double pole single throw)


DPDT (double pole double throw)


It contains 6 terminals: 2 input terminals (poles) and 4 output terminals (throws). In this type of electrical circuit, one pair of throws is connected to two terminals of poles.



DPDT (double pole double throw) Toggle Switch
DPDT (double pole double throw) Toggle Switch

2 poles, 6 throws


It contains 1 input terminal (pole) and 6 output terminals (throw) for each of the poles. In electrical circuits, this type of switch is used to change features for the same input terminals.


Push-button switch


When this switch is pressed, the circuit will be closed for current flow. If pressure is released from the push-button switch, contact will break and current flow will stop.



Push-button switch
Push-button switch


Pressure switch


From a set point, a pressure switch is used to increase or decrease the pressure. It is comprised of a C-shaped diaphragm. It is used in various industries for sensing air pressure, oil pressure, and water pressure.



Pressure Switch
Pressure Switch


Temperature Switch


It is comprised of a resistance temperature device that senses temperature. It is operated based on the measured temperature value.



Temperature Switch
Temperature Switch


Toggle switch


It is used in household applications. It has a lever that will be moved up or down to turn on and off.



Toggle Switch
Toggle Switch


Rotary Switch


It is used in channel selectors, range selectors, and band selectors. In electrical circuits, this type of switch is used to connect one line to one of many lines.



Rotary Switch
Rotary Switch


Selector switch


This switch is driven with a rotary knob or level of some sort to select one or more positions. Selector switches can rest in any of their respective positions or contain a spring-return mechanism for momentary operation.



Selector switch
Selector switch


Joystick switch


It is driven by a lever free to move in more than one axis of its motion. Depending on the way the lever is pushed, different switch contact mechanisms are activated, and it also depends on how far the lever is pushed. Crane and robot control apps. Some of the switches are designed specifically to be operated by the motion of machines instead of the human operator's hand. Motion-operated switches are called limit switches as they limit the motion of the machine by the process of turning the component's actuating power.



Joystick Switch
Joystick Switch


Limit switch


Limit switches are very similar to rugged toggle or selector hand switches fitted with levers pushed by machine parts.



Limit Switch
Limit Switch


Proximity Switch


It is used to sense the approach of metallic machine parts by using either a magnetic or high-frequency EMF.



Proximity Switch
Proximity Switch


Simple Proximity Switch


This type of switch uses a permanepnt magnet to activate a sealed switch mechanism when the machine part gets close.

Most of the proximity switches work similar to that of the metal detector, i.e., energize a coil of wire using a high-frequency current and electronically monitor the current magnitude.


Optical switch


An optical switch is another type of proximity switch. It is comprised of a light source and a photocell. The position of the machine was detected by the interruption or light beam reflection. One of the significant applications of the optical switch is that it can be used in dangerous areas to detect personnel entry by using beams of light.



Optical Switch
Optical Switch

Relationship between power supply and switch


The relationship between a power supply and a switch in an electrical system is fundamental, as the switch is often used to control the flow of electrical power from the power supply to various devices or components within a circuit.


 Control of Power Flow


Switch as a Controller


A switch is a device that can open or close an electrical circuit. When the switch is closed, it allows electric current to flow, connecting the power supply to the load (device or component). When the switch is open, it interrupts the circuit, cutting off the power supply to the load.



 On/Off Functionality


 Switch for Power On/Off


In many applications, switches are used to turn devices or systems on and off. For example, a light switch controls the power supply to a light bulb, allowing the user to turn the light on or off as needed.



 User Interface


 Manual Control


Switches provide a manual means for users to control the power supply to specific devices. Users can physically operate the switch to initiate or terminate the flow of electrical power.



 Safety and Energy Conservation


Energy Management


Switches are essential for managing energy consumption. Turning off a switch when a device is not in use helps conserve power and reduce energy costs.



 Integration in Circuits


Inclusion in Circuit Design


Switches are often integrated into electrical circuits alongside power supplies to enable controlled power distribution. They can be part of simple circuits, such as those used in household appliances, or more complex systems in industrial applications.



 Types of Switches


 Compatibility


Different types of switches may be used based on the specific requirements of the application. For example, a simple toggle switch might be suitable for a home lighting circuit, while a more sophisticated switch with additional features might be used in a complex electronic system.



 Protection and Safety


Circuit Breaker Function


In some cases, switches are combined with circuit breakers for enhanced safety. Circuit breakers can automatically interrupt the power supply if there is an overcurrent or fault, preventing damage to the connected devices and reducing the risk of electrical fires.


Application of Switches


Switches find numerous applications in various electrical and electronic systems. Their primary function is to control the flow of electric current in a circuit, either by opening or closing the circuit. Here are some common applications of switches:



 Lighting Control


Light Switches: The most common application of switches is for turning lights on and off in homes, offices, and industrial settings.



 Electronic Devices


Power Switches: Switches are used to control the power supply to electronic devices such as computers, televisions, and audio systems.


Toggle Switches: Found on electronic equipment for various functions, including changing modes or settings.



 Appliances


Household Appliances: Many household appliances, such as ovens, refrigerators, washing machines, and fans, incorporate switches for user control and safety.



 Automotive Industry


Car Switches: In vehicles, switches are used for various functions, including turning on headlights, adjusting mirrors, and activating windshield wipers.



 Industrial Control


Machine Control: Switches are used in industrial settings to control machines and equipment, allowing operators to start, stop, or change operating modes.



 Telecommunications


Telephone Switches: Traditional telephones use switches to open and close the circuit during dialing and conversation.



 Home Automation


Smart Switches: In modern home automation systems, smart switches allow users to control lights, appliances, and other devices remotely using smartphones or voice commands.



 Security Systems


Alarm Systems: Switches are used in security systems to detect the opening or closing of doors and windows, activating alarms.



 Computer and Electronics


 Keyboard Switches: Computer keyboards use switches to register key presses.


 Push Button Switches: Used in various electronic devices for momentary contact, like in the case of reset buttons.



 Environmental Control


Thermostats: Switches are used in thermostats to control heating and cooling systems in homes and buildings.



 Medical Devices


Medical Equipment: Switches are integrated into medical devices for user control and operational functions.



 Power Distribution


Circuit Breakers: While not traditional switches, circuit breakers function similarly by interrupting the flow of current for safety reasons, protecting electrical circuits from overloads and faults.


Aerospace


Aircraft Controls: In aviation, switches are used in cockpit controls for various functions, including navigation and communication systems.


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