Switches

Introduction

A switch is a device that is designed to interrupt the current flow in a circuit, in other words, it can make or break an electrical circuit. Every electrical and electronics application uses at least one switch to perform the ON and OFF operation of the device.

So, the switches are part of a control system and without it, control operation cannot be achieved. A switch can perform two functions, namely fully ON by closing its contacts or fully OFF by opening its contacts. When the contacts of a switch are closed, the switch creates the closed path for current flow, and hence load consumes the power from the source. When the contacts of a switch are open, no power will be consumed by the load.

TYPES OF SWITCHES

Mechanical Switch

• Mechanical switches require physical or manual contact with the switch for operation.

Electrical Switch

• Electrical switches do not require physical or manual contact, it can operate. Electrical switches operate under the action of semiconductors.

TYPES OF MECHANICAL SWITCHES

There are different types of switches based on the number of poles and throws.

1. Single pole single throw, (SPST).
2. Single pole double throw, (SPDT).
3. Double pole single throw, (DPST).
4. Double pole double throw, (DPDT).
5. Intermediate switch.

Latch Switch

• The latch switch holds its state whether ON or OFF until the new commands initiate this switch.

Momentary Switch

• Momentary holds the state only when the specific command is presented only.

Latch switch and Momentary switch are eight types.

1. Push Button Switch.
2. Limit switch.
3. Pressure switch.
4. Float switch.
5. Temperature switch.
6. Toggle switch.
7. Rotary switch.
8. Joystick switch.

Single Pole Single Throw, (SPST)

• The SPST is a basic ON or OFF switch that is used to connect or break the connection between two terminals. The power supply for the low circuit is given by this switch. The application of the SPST switch is also called a toggle switch which has one input and one output.

Single Pole Double Throw, (SPDT)

• The SPDT switch is a three-terminal switch where one terminal is used as input and the other remaining two terminals are used as outputs. The application of the SPDT switch is mainly involved in a three-way circuit to turn ON or OFF a light from two locations like from the top and bottom of a stairway.

Double Pole Single Throw, (DPST)

• The DPST switch consists of two poles, which means it includes two identical switches located side by side. In one single toggle which means that two discrete circuits are controlled at a time through one push.

Double Pole Double Throw, (DPDT)

• This switch is equal to two SPDT switches, it means two separate circuits, connecting two inputs of each circuit to one of two outputs. The controls the switch position number of ways and from the two contacts, each contact can be routed.

Intermediate Switch

These switches are where three points control the same circuit. It is a very versatile switch and can be used for most lighting situations but in reality, it is more expensive so you would normally only use it when needed. You have three switches controlling one light, then the middle one needs to be intermediate.