Types of Switches – Definition, Mechanical and Momentary Control

Introduction

There are two types of switches: electrical switches and mechanical switches. Switches are electrical components that are used to turn any electric device on and off. An open circuit develops when the switch is off and no current flows. A closed circuit indicates that the current is flowing and the switch is on.

What is a Switch?

A switch is a device that enables or regulates the passage of electricity. Current flows when the switch is turned on because the electric circuit is closed. When the switch is turned off, the current ceases to flow since the circuit is still open.

As a result, switches are an essential component of the control system; without them, control action would be impossible. The diagram below can help you understand this better:

Open and Closed Switches

Different Types of Switches

In general, two types of switches are used in an electric circuit:

1. Electrical switches: They run under the control of a semiconductor.
2. Mechanical switches: These need manual touch to work and are classified according to the number of poles (number of input circuits accessible to the switch) and throws (no. of the path for the flow of current available to the switch).

What are Electrical Switches?

These are also known as solid-state switches since they have no physical parts and hence no physical interaction. Semiconductor switches regulate many appliances, including motor drives and HVAC systems.

Electrical Switch Types

There are several electrical switches, some of which are as follows:

1. Bipolar Transistors

A bipolar transistor’s functions are similar to a standard switch. When you turn on an NPN or PNP transistor, a base current is required to operate it as a switch.

Circuit of Bipolar Transistors

1. Power Diode

One can utilize Silicon to manufacture power diodes. When the PN junction of a power diode is forward-biased, it acts as a switch-on; when reverse-biased, it works as a switch-off.

1. MOSFET

MOSFET stands for Metal Oxide Semiconductor Field Effect Transistor. It is a unipolar switching device. You can select the on and off states by adjusting the input voltage and resistance across the drain and source because the device is voltage controlled.

What are Mechanical Switches?

Mechanical switches are categorized according to their poles and throws.

1. Single Pole Single Throw Switch
2. Single Pole Double Throw Switch
3. Double Pole Single Throw Switch
4. Double Pole Double Throw Switch
5. Two Pole Six Throw Switch
6. Momentary Control Switches

Mechanical Switches

Single Pole Single Throw Switch

It has one input terminal called the pole and one output terminal called via this and may be utilized in a single loop or a closed path.

Single Pole Double Throw Switch

It has one input and two output terminals and may be used as a selection switch with a selector switch, allowing us to provide the current two loops.

Double Pole Single Throw Switch

These are used to control two circuits at the same time. This device has two input terminals and two output terminals. In these circuits, the two switches are linked by a single lever and work simultaneously.

Double Pole Double Throw Switch

This switch has six terminals, two poles, and four throws, two for each terminal on each pole. Because it is a dual ON/off switch, it has two ON settings.

Two Pole Six Throw Switch

Each pole contains one input terminal and six output terminals (throw). This arrangement has a total of 12 output terminals. In the circuit, this is utilized to switch between features for the same input terminals.

Momentary Control Switches

There are several types of momentary switches.

1. Temperature Switch: This sort of switch is seen in devices such as RTDs (resistance temperature devices). The detected temperature determines the operation of this switch.
2. Toggle Switch: This is the most common switch found in most domestic appliances. We may turn the device on or off by moving the lever up and down.
3. Rotary Switch: This switch is commonly used to connect two lines. Except for the switch configuration, the rotary switch is quite similar to a single-pole multi-throw switch.

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