Switches
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September 1, 2022
Any device that may be used to temporarily halt the passage of electrons via a circuit can be considered an electrical switch. In its most basic form, switches can either be fully engaged (sometimes referred to as "closed") or entirely disengaged (often referred to as "open").
Types of Switches
Hand Switches
The simplest kind of switch is the kind in which the motion of an actuating mechanism brings two electrical conductors into contact with each other. This is the most basic kind of switch.
Other switches are more complicated and feature electrical circuits that are able to turn on or off depending on the type of physical stimuli (such light or a magnetic field) that is detected by the switch.
In any event, the ultimate output of any switch will be (at the very least) a pair of wire-connection terminals. These terminals will either be connected together by the switch's internal contact mechanism ("closed") or they will not be connected together ("open") depending on the state of the switch.
Toggle Switches - A lever that can be tilted in one of two or more positions is typically used to activate toggle switches. A typical example of a toggle switch is the light switch that is utilized in the wiring of residential homes.
The majority of toggle switches will stop at any one of their lever positions, but some of them contain an internal spring mechanism that returns the lever to its normal position, which enables "momentary" operation. Toggle switches with this type of mechanism are less common.
Push Button Switches - Pushbutton switches are devices with two states that are activated by depressing and then releasing a button on the device. For transitory operation, the vast majority of pushbutton switches are equipped with an internal spring mechanism that returns the button to its "out" or "unpressed" state.
Some pushbutton switches will latch in either the on or off position depending on whether the button is pressed once or multiple times. Other pushbutton switches will remain in the "in" position, often known as the "pressed" position, until the button is pushed back out.
Selector Switch - A rotary knob or a lever of some form is used to pick one of two or more locations when a selector switch is activated.
Selector switches, much like toggle switches, can either rest in any of their positions or have spring-return mechanisms for momentary activity. Toggle switches are the more common type.
Joystick Switch - An action that activates a joystick switch is performed by a lever that is free to travel along more than one axis of motion. The direction in which the lever is pressed, and sometimes the amount of force with which it is pushed, both have a role in determining which of numerous switch contact mechanisms are activated.
The direction of joystick lever motion that is necessary to actuate the contact is represented by the circle-and-dot notation that may be found on the switch symbol. Cranes and robots frequently make use of joystick hand switches as their control mechanism of choice.
Proximity Switches - By employing either a magnetic or a high-frequency electromagnetic field, proximity switches may detect when a metallic machine part is getting close to them.
When a machine part approaches close to a simple proximity switch, the switch is activated by a permanent magnet, which then triggers a sealed switch mechanism (typically 1 inch or less).
Complex proximity switches operate in a manner analogous to that of a metal detector. They do this by energizing a wire coil with a high-frequency current and electronically monitoring the magnitude of that current.
The monitoring circuit will be tripped if a metallic part that is not necessarily magnetic comes into sufficient proximity to the coil. This will cause the current to increase.
Optical Switches - A further type of proximity switch is the optical switch, which consists of a photocell and a light source as its component parts. The interruption or reflection of a light beam is the method that is used to detect the position of a machine.
Beams of light can be used in safety applications to detect when individuals have entered a potentially hazardous location. This is another area in which optical switches are beneficial.
Process Switches
Speed Switches - The rotating speed of a shaft can be determined by these switches either through a centrifugal weight mechanism that is installed on the shaft or through some type of non-contact detection of shaft motion such as optical or magnetic.
Pressure Switches - If the pressure of a gas or liquid is applied to a piston, diaphragm, or bellows, which transforms pressure to mechanical force, then the mechanism that controls the switch can be activated by the pressure of the gas or liquid.
Temperature Switches - The "bimetallic strip" is a thin strip of two metals that are linked back-to-back. Each metal has a variable rate of thermal expansion, hence the bimetallic strip can be used as a temperature-sensing device at a low cost.
Because of the different rates of thermal expansion between the two metals, the strip will bend depending on whether it is heated or cooled. When the strip is bent, it can be used to operate a switch contact mechanism that is located elsewhere.
Other types of temperature switches consist of a tiny tube connected to a pressure-sensing switch that is connected to a bulb made of brass that is either filled with a liquid or gas. Because of the increase in temperature, the gas or liquid inside the bulb expands, which results in a rise in pressure that ultimately triggers the switch mechanism.
FREQUENTLY ASKED QUESTIONS:
What are Switches?
The ability to manage continuity between two places is the primary function of a switch, which is an electrical device that is often electromechanical in nature.
How can you categorize switch types?
Switches can be categorized into three: Hand Switches which are actuated by human touch; Limit Switches are actuated by machine motion; and Process Switches are actuated by changes in some physical process (temperature, level, flow, etc.).
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