Electrical & Mechanical Switches & Types:
Introduction:
The 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 them, 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 has the ability to perform the operation. Electrical switches operate under the action of semiconductors.
Types of Mechanical switches:
Mechanical switches are further classified into different types of switches based on the number of poles and throws. There are five types.
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.
Mechanical Switches can also be categorized on the basis of holding the current state. There are two types. Latch Switch, and Momentary Switch.
latch switch:
The latch switch holds its state whether ON or OFF until the new commands initiated this switch.
Momentary switch:
The momentary switch holds the state only when the specific command is presented only.
Latch Switch and Momentary Switch are 8 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.
SPST (Single Pole Single Throw):
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 a light switch and it is also called a toggle switch. This type of switch has one input and one output.
SPDT (Single Pole Double Throw):
The SPDT switch is a three terminal switch, one terminal is used as input, and the remaining two terminals are used as outputs. It joins a mutual terminal to one or the other of two terminals. 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 & bottom of a stairway.
DPST (Double Pole, Single Throw):
The DPST switch consists of two poles which means it includes two identical switches located side by side. This switch is operated by one single toggle, which means that two discrete circuits are controlled at a time through one push.
DPDT (Double Pole Double Throw):
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 switch position controls the number of ways and from the two contacts, each contact can be routed.
Intermediate Switch:
An Intermediate Switch is where three points control the same circuit. This 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. That is when you have three switches controlling one light, then the middle one needs to be intermediate.
Push Button Switch:
A push button switch to make the switch allows electricity to flow between its two contacts when held in. When the button is released, the circuit is broken. This type of switch is also known as a Normally Open Switch.
Limit Switch:
Limit switches are used for controlling machinery as part of a control system, as safety interlocks, or to count objects passing a point. A limit switch is an electromechanical device that consists of an actuator mechanically linked to a set of contacts. When an object comes into contact with the actuator, the device operates the contacts to make or break an electrical connection.
Pressure Switch:
This type of switch consists of a C-shape diaphragm. According to pressure, this diaphragm is indicating pressure.
These switches are used to sense the pressure of air, water, or oil, in industrial applications. This switch operates when the pressure of the system is increase or decreases from a set point.
Float Switch:
A float switch is a type of level sensor, a device used to detect the level of liquid within a tank. The switch may be used to control a pump, as an indicator, as an alarm, or to control other devices.
Temperature Switch:
This type of switch consists of temperature sensing devices like RTD and thermostats. This switch operates according to the value of the measured temperature.
Toggle Switch:
This type of switch is commonly used in household applications to ON and OFF electrical appliances. It has a lever by which we can move up or down to ON and OFF appliances.
Rotary Switch:
This type of switch is used to connect one line with one of the many lines. Nob of multi-meter, channel selector, range selector metering device band selector in communication devices is the example of this type of switch. This switch is the same as the single pole multi-throw switch. But the arrangement of this switch is different.
Joystick Switch:
A joystick switch is actuated by a lever free to move in more than one axis of motion. One or more of several switch contact mechanisms are actuated depending on which way the lever is pushed, and sometimes by how far it is pushed. The circle-and-dot notation on the switch symbol represents the direction of the joystick lever motion required to actuate the contact. Joystick hand switches are commonly used for crane and robot control.
Thank You