This switch has three terminals: one is input contact and remaining two are output contacts.The contacts of SPST can be either normally open or normally closed configurations.It switches a single circuit and it can either make (ON) or break (OFF) the load.This is the basic ON and OFF switch consisting of one input contact and one output contact.Most of the switches are designed to have either one or two throws, which are designated as single throw and double throw switches. The number of throws represents the number of states to which current can pass through the switch. Most of the switches are designed have one, two or three poles and are designated as single pole, double pole and triple pole. The pole represents the number of individual power circuits that can be switched. Mechanical switches can be classified into different types based on several factors such as method of actuation (manual, limit and process switches), number of contacts (single contact and multi contact switches), number of poles and throws (SPST, DPDT, SPDT, etc.), operation and construction (push button, toggle, rotary, joystick, etc.), based on state (momentary and locked switches), etc.īased on the number of poles and throws, switches are classified into following types. These are activated by semiconductor action. Mechanical Switches are physical switches, which must be activated physically, by moving, pressing, releasing, or touching its contacts.Įlectronic Switches, on the other hand, do not require any physical contact in order to control a circuit. Latched Switches on the hand, maintain the contact until it is forced to the other position.īasically, Switches can be of two types.Momentary Switches (like push buttons, for example) are used to make momentary contact (for a brief time or as long the button is pressed). Another important characteristic of a switch is its action i.e., whether it is a Momentary or Latched action.For example, a three pole six throw switch is often represented as 3P6T. If the number of poles or throws are greater than 2, then the number is often directly used.Some standard numbers of poles and throws are Single (1 pole or 1 throw) and Double (2 poles or 2 switches).Number of poles and throws are used to describe a switch. A pole represents a contact and a throw represents a contact-to-contact connection. The two important characteristics of a switch are its Poles and Throws.Characteristics of a Switchīefore proceeding further and looking at different types of switches, let us see some important points on the Characteristics of a Switch. In some applications, multi way switching is employed (like building wiring), where two or more switches are connected to control an electrical load from more than one location, like a Two Way Switch, for example. In home and office applications, we use simple rocker switches to turn ON and OFF appliances like lights, computers, fans etc.
There are numerous applications of switch, found in wide variety of fields such as homes, automobiles, industrial, military, aerospace and so on.
When the switch is in position A, the lamp 1 turns ON and while it is in position B, lamp 2 turns ON. When the contacts of a switch are open, no power will be consumed by the load as shown in below figure.Īnother important function of a Switch is to divert the flow of electric current in a circuit. When the contacts of a switch are closed, the switch creates a closed path for the current to flow and hence load consumes the power from source. A switch can perform two functions, namely fully ON (by closing its contacts) or fully OFF (by opening its contacts). So, switches are a part of the control system and without it, control operation cannot be achieved. Every electrical and electronics application uses at least one switch to perform ON and OFF operation of the device. In simple words, a Switch can make or break an electrical circuit.
A Switch is a device which is designed to interrupt the current flow in a circuit.