Types of electrical switches 9gag instagram


Electrical Switches are electromechanical devices that are used in electrical circuits to control power, detect when systems are outside their operating ranges, signal controllers of the whereabouts of machine members and work pieces, provide a means for manual control of machine and process functions, control lighting, and so on. Switches come in a variety of styles and are actuated by hand, foot, or through the detection of pressure, level, or objects. Switches can be simple on-off types or can have multiple positions that, for instance, can control the speed of a multi-speed fan. Switch operators can be found in various shapes and sizes, such as toggles or buttons, and can be furnished in a variety of colors. Types of Electrical Switches

Switch function is defined by the number of poles and throws the switch has. “Poles” are individual circuits the switch controls (e.g., a “3-pole” switch has three circuits controlled by the same throw). “Throws” are unique positions or settings for the switch (e.g., a “double-throw switch” can operate in two different positions like on/off, high/low, etc.). Combining the number of poles and throws gives a succinct description of the switch’s function, so the function of, for instance, a “single-pole, double-throw” switch is implicit. Switch types are commonly abbreviated for brevity, so a single-pole, double-throw switch would be referred to as an “SPDT” switch.

The simplest type of switch is a single-pole, single-throw (SPST) device that functions as an on-off switch. Double-pole, double-throw (DPDT) switches are commonly employed as internal polarity reversing circuits. Switches of up to four poles and three throws are common and some have breaks. Foot Switches

Level Switches are electro-mechanical devices used to detect the level of liquids, powders, or solids. They are mounted in tanks, hoppers, or bins, and can provide output to a control system. In some instances they can be used to actuate a device directly, such as level switches used in residential sump pumps.

Limit Switches are electro-mechanical devices designed to sense motion and position mechanically and provide output signals to a controller. They are available as bare switches, or in rugged enclosures intended for the tough environment of a factory floor.

Pull Chain Switches are electro-mechanical devices that are hand operated and used to switch a circuit on and off, or step a circuit through increasing power levels. Their most common application is in lighting where they are used to switch lamps. Pull Rope Switches are used as emergency stop devices.

Pull chain switches can be used for manual control of overhead lights and fans. As rope-pull switches, they are used for emergency stop devices, for example along the length of an in-running roll. They are sometimes called Rope Pulls or Cable Pulls. Pushbutton Switches

Toggle Switches are hand operated electro-mechanical devices used for switching circuits. They are actuated by a lever which is pushed through a small arc. Moving the lever back and forth opens and closes an electrical circuit, while the lever position gives a quick visualization of the circuit status.

Wall switches are specifically designed to operate on line voltage and fit inside standard electrical boxes. They are standard items in residential and commercial construction. A variety of decorator or designer styles can set these switches apart from industrial switches where aesthetics are less of a concern. Applications and Industries

Switches are used in myriad applications in every industry—such as aerospace, automotive, chemical, communication, marine, medical, military, petrochemical, and transportation—as well as in the commercial and residential sectors. A ubiquitous technology, switches can be found as part of the user interface for nearly every electrical and mechanical product. Some typical places to find switches include:

Generally, the specific application will help determine what kind of switch is best for the job. Because the switch’s form factor is so critical, a selection can’t be made until the purpose is determined. Considerations Poles, Throws, and Form Factor

For instance, a simple light switch might need only one pole and one throw, but it could take many forms: A pull chain, pushbutton, rocker, rotary, slide, toggle, and the familiar wall switch are all common. Another example would be a level switch used to detect if a tank is getting close to its capacity; this kind of switch has just one major form factor but can have different combinations of poles and throws. Switch selection must be made with the entire system’s function and goals in mind.

Also keep in mind that different form factors will have different physical considerations—an electrical rotary switch will have a maximum power rating you must be aware of but a level switch will not, and a pressure switch will have a pressure rating that a wall switch will not. Pricing and Quality

Switch prices and build quality can vary dramatically. The simplest, cheapest switches can cost only a few dollars while complicated systems can cost hundreds apiece. Quality can be hard to judge but an industry standard certification will ensure that a given switch meets certain minimum guidelines prescribed by a respected agency or government.

There are no important distinctions between most new, used, rebuilt, and remanufactured switches. New switches will be more expensive but should come with a warrantee; pre-owned switches will be cheaper but may not have a warrantee or may have lower reliability. This tradeoff must be carefully weighed, especially for critical components and applications.

There are many qualities that play into switch selection, some of which have already been discussed. Here an in-depth description is given for many significant characteristics. The attributes are broken into two main sections—switch construction and electrical specifications. Switch Construction

The circuit configuration refers to the number of poles, throws, and breaks the switch has. Switches commonly have anywhere between one and four poles and one and three throws; some have either single or double breaks. Contact Plating and Terminal Plating

The Ingress Protection (IP) rating and National Electrical Manufacturers Association (NEMA) enclosure rating are official guidelines that show what kind of environment a switch’s housing is capable of withstanding. Stricter ratings are more appropriate for less forgiving work areas. Mounting Type

Used in changeover switches, there are two types of contacts: Non-shorting (“break before make”, or BBM) and shorting (“make before break”, or MBB). Non-shorting changeover switches interrupt one changeover circuit before activating the other; shorting changeover switches will very temporarily activate both circuits. This can affect circuit function and choosing the correct one is essential. Current Rating

These attributes refer to the number of electrical and mechanical operations, respectively, that the switch is rated to perform before failing. Higher life ratings mean the switch will last longer before needing service or replacement. Power Rating