Introduction to an Electric Switch: Switch is an electrical component which can make or break an electrical circuit automatically or manually. The switch mainly works with ON (open) and OFF (closed) mechanisms. Numerous circuits hold switches that control how the circuit works or actuate different circuit characteristics. The classification of switches depends on the connection they make.

Two vital components that confirm what sorts of connections a switch makes are pole and throw. The classification of switches depends on the connection they make. Two vital components that confirm what sorts of connections a switch makes are pole and throw. This article teaches about electrical switches, their types, their applications, and much more. Read on to find out.

What is an Electrical Switch?

An electric switch is a device – usually electromechanical – used to open and close an electric circuit. This disables and enables the flow of electric current, respectively. Switches are synonymous with the interruption, or some form of manipulation, of the flow of electric current or, more elementarily, the flow of electrons.

The appreciation of the underlying principle behind a switch comes along with electricity and the use of conducting material for electric current flow. A discontinuity in the conductor implies the current does not flow. Needing a switch is as old as the discovery of the first practical application of electricity and the construction of the first electrical circuit.

By inference, the above switch effectively puts an air gap in some parts of the circuit. The air gap has different electrical properties to the conducting material building the circuit, and if the air gap is big enough, it stops current flow. Fundamentally, that is what a switch does, i.e. alter the electrical properties of some part of a circuit to alter the flow of electrons in that circuit. Appreciating this would be important, taking cognizance of switches whose operation never involves physical movement.

Operation of Electric Switches

Switches provide a means to control the electrical current supply to electric loads. One crucial aspect is to conduct electric current. The other aspect is the ability to break the current. For some electric switches, breaking the circuit involves an air gap between two contacts. The contacts must be opened fast enough to ensure the desired operation.

For most electronic switches, the state of the connection is changed by changing the effective resistance of that connection. The resistance can be made very high to effectively make it an open circuit or low enough to close the circuit. It is common to have no physically moving components on the switch itself.
Another important aspect is the ability to respond to the actuator.

The actuator may be automatic or manual and is intended to make or break the circuit. The purpose of the actuator is to initiate some change in the state of the connection. Actuation may take the form of physical movement e.g., a lever or a slide. It can also take the form of another event, e.g., overvoltage or light intensity variation.

In the case that equipment to be connected through that switch may not be protected, a fuse is often incorporated as part of the switch.

Types of Switches

There are 4 types of switches, namely SPST, SPDT, DPST and DPDT.

SPST Switch

The Single Pole Single Through (SPST) is a basic on/off switch that just connects or breaks the connection between two terminals. The power supply to a circuit is switched by the SPST switch.

SPDT Switch

The Single Pole Double Throw (SPDT) switch is a three terminal switch, one for input and other two for the outputs. It connects a common terminal to one or the other of two terminals. For using the SPDT switch as SPST switch then just use the COM terminal instead of other terminals.

DPSTR Switch

DPST is abbreviation for Double Pole Single Throw. Double pole means that the unit contains two identical switches, side by side, and operated by one single toggle or lever. This means that two separate circuits are at a time controlled through one push.

DPDT Switch

DPDT is a double pole double throw switch; this is equivalent to two SPDT switches. It routes two separate circuits, connecting each of two inputs to one of two outputs. The position of the switch determines the number of ways in which each of the two contacts can be routed.

Other Types of Switches

• Push Button Switch
• Toggle Switch
• Limit Switch
• Float Switches
• Flow Switches
• Pressure Switches
• Temperature Switches
• Joystick Switch
• Rotary Switches

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