Different Types of Electrical Switches Normally Used in Circuits
There are so many types of electrical switches available from very simple to very complex switches used in electrical circuit controlling system.Switch may different types but the basic function of electrical switch is to open or close. The meaning of electrical switch is to open or close the electrical path to equipment.
What are the different types of electric switches that uses in every home?
When we name the switches, we find some common and lovely switches as below:
SPST- Single pole, single throw switch. It is simple on-off switch just having two terminals are either connected together or disconnected from each other by phase P1 and terminal T1.
It is also classified into two types: SPST-NO-single pole, single throw, normally open known as Type-A and SPST-NC- single pole, single throw, normally closed known as Type-B.
The most common and simple type of electric light switch is the one way switch. A very simple one way press operation and instant effects. Their operational simplicity makes user comfort a reality.
SPDT- Single pole, double throw. It is simple break-before-make changeover switch common terminal is connected either to Terminal T1 or Terminal T2.
Similar as SPDT some manufacturer use SPCO/SPTT meaning single pole changeover or single pole, center off or single Pole Triple Throw for switches.
Two way switches are very much different and are extensively found in modern homes that have limited number of switching accessories. Their usage is very efficient and adds to the convenience of the users significantly.
DPST- Double pole, single throw. DPST actually equivalent to two SPST switches together controlled by a single mechanism.
SPST- Single pole, single throw switch. It is simple on-off switch just having two terminals are either connected together or disconnected from each other by phase P1 and terminal T1.It is also classified into two types: SPST-NO-single pole, single throw, normally open known as Type-A and SPST-NC- single pole, single throw, normally closed known as Type-B.
The most common and simple type of electric light switch is the one way switch. A very simple one way press operation and instant effects. Their operational simplicity makes user comfort a reality.
SPDT- Single pole, double throw. It is simple break-before-make changeover switch common terminal is connected either to Terminal T1 or Terminal T2.Similar as SPDT some manufacturer use SPCO/SPTT meaning single pole changeover or single pole, center off or single Pole Triple Throw for switches.
Two way switches are very much different and are extensively found in modern homes that have limited number of switching accessories. Their usage is very efficient and adds to the convenience of the users significantly.
DPST- Double pole, single throw. DPST actually equivalent to two SPST switches together controlled by a single mechanism.
Some manufacturer use DPCO - double pole change over for switches with a stable center position.
2p6t- Two pole, six throw. 2p6t is actually a changeover switch with a common terminal which can connect to L1 to L6 with a two pole second switch controlled by a single mechanism.
What type of switch is used in an electrical panel?
The switches used in electrical panels may manual switches or automatic switches. The manual operated switches such as light switch, fan switch or manual switch for any kind of electrical circuit of electrical equipment.
Automatically operated different switches can be used to control the motions of machines such as to indicate a door has reached its full open position or full close position.
Switches may be operated by process variables such as pressure, temperature, flow, current, voltage, and force, acting as sensors in a process and used to automatically control a system. There are many different switch designs. The most common electrical panel switches are:
Slide switch: A slide switch has a knob that you can slide back and forth to open or close the contacts. Slide switches we find as SPST (single pole single throw), DPDT (double pole double throw) switch.
Toggle switch: A toggle switch has a lever that we flip up or down to open or close the contacts. The common light switch used in household wiring is an example of a toggle switch.Toggle switches are actuated by a lever angled in one of two or more positions. Most famous type of toggle Electrical Switches contain two positions.
Rotary switch: A rotary switch has a knob that we turn to open and close the contacts. The switch in the base of many tabletop lamps is an example of a rotary switch.
Rocker switch: A rocker switch has a seesaw action. We press one side of the switch down to close the contacts, and press the other side down to open the contacts.
Knife switch: A knife switch is the kind of switch Igor throws in a Frankenstein movie to reanimate the creature. In a knife switch, the contacts are exposed for everyone to see.
Mercury switch:The mercury switch consists a drop of mercury inside a glass bulb with 2 contacts. The two contacts pass through the glass, and are connected by the mercury when the bulb is tilted to make the mercury roll on to them.
Push-button switch: A push-button is simply button which switch mechanism for controlling some aspect of a machine or a process. Though even many un-biased buttons require a spring to return to their un-pushed state. These switches are used for bell circuits, refrigerator lighting circuit. Some of push button on industry also contain indication lights such as Red, Green and yellow.Special types of switches are:
Differential Pressure switch: Differential pressure switch is a device which utilizes a differential air pressure to actuate an electric switch at a preset actuation point. This may be the difference between two positive or two negative pressures, one of each, or a positive and atmospheric or a negative and atmospheric pressure. The electric switch may be used to start or stop motors or fans, open or close dampers or louvers, light a warning signal, sound alarms, etc.
Foot switch: Some machinery like garments factory swing machine use foot switch that operated by foot instead of hand.
You may read the different types of switches in details in another articles:
28 Basic Symbol of Electrical Switches that Use Widely
Symbol for electrical switches is important to electricians to select proper switches during wiring.Following 28 switch-symbol is the most common uses stitches in our work place.
This is not the limit, there are many switches and switch-symbol for them.
You may read the another article to know the detail wiring system on-
ELECTRICAL DISTRIBUTION BOARD DB WIRING.
Top Brands Electrical Switches that Uses in Bangladesh
Siemens - Huge scale of operation and range, adapted to Bangladesh, electrical switches of Siemens work irrespective of the load, products are reliable. In house Siemens switches and sockets are used as first choose in high grade equipment.
Schneider - French multinational, develops technology and solutions that make energy safe, reliable, efficient, green and productive. Schneider switches and sockets are popular in industry sector.
Havells - Indian company, the switches and sockets are widely used in India and Bangladesh.
Wipro - Modular switches are equipped with glossy finish switches flaunt radium markers for visibility at night, protective spark shield for added safety, thermostat housing for safe electrical insulation, and silver coated metal parts for better current conductivity.
Polycab - specializes in high and low voltage switch-gear, different range of solutions that are suitable for all kinds of HV/LV power engineering requirements including protection, metering, and control equipment.
Orpat - Gujarat based company, known for silver series modular switches and copper series modular switches, which are gradually gaining in popularity in the country.
What is the Difference between Isolation and Switching?
The consumer’s main switchgear must be readily accessible to the consumerand be able to:
- isolate the complete installation from the supply;
- protect against overcurrent;
- cut off the current in the event of a serious fault occurring.The regulations identify four separate types of switching: switching for isolation,switching for mechanical maintenance, emergency switching and functionalswitching.
Isolation
is defined as cutting off the electrical supply to a circuit or item ofequipment in order to ensure the safety of those working on the equipment bymaking dead those parts which are live in normal service.
The purpose of isolation switching is to enable electrical work to be carried outsafely on an isolated circuit or piece of equipment. Isolation is intended for useby electrically skilled or supervised persons.
An isolator is a mechanical device which is operated manually and used toopen or close a circuit off load. An isolator switch must be provided close to thesupply point so that all equipment can be made safe for maintenance.
Isolatorsfor motor circuits must isolate the motor and the control equipment, and isolatorsfor discharge lighting luminaires must be an integral part of the luminaire sothat it is isolated when the cover is removed or be provided with effective localisolation (IET Regulation 537.2.1.6).
Devices which are suitable for isolation areisolation switches, fuse links, circuit-breakers, plugs and socket outlets. Theymust isolate all live supply conductors and provision must be made to secure theisolation (IET Regulation 537.2.2.4).
Isolation at the consumer’s service position can be achieved by a double-poleswitch which opens or closes all conductors simultaneously. On three-phasesupplies the switch need only break the live conductors with a solid link in theneutral, provided that the neutral link cannot be removed before opening theswitch.
The switching for mechanical maintenance
requirements is similar to those forisolation except that the control switch must be capable of switching the full loadcurrent of the circuit or piece of equipment.
The purpose of switching for mechanical maintenance is to enable non-electricalwork to be carried out safely on the switched circuit or equipment.
Mechanical maintenance switching is intended for use by skilled but non-electrical persons. Switches for mechanical maintenance must be manuallyoperated, not have exposed live parts when the appliance is opened, must beconnected in the main electrical circuit and have a reliable on/off indication orvisible contact gap (IET Regulation 537.3.2.2).
Devices which are suitable forswitching off for mechanical maintenance are switches, circuit-breakers, plugand socket outlets.
Emergency switching
involves the rapid disconnection of the electrical supplyby a single action to remove or prevent danger.The purpose of emergency switching is to cut off the electrical energy rapidly
toremove an unexpected hazard.Emergency switching is for use by anyone.
The device used for emergencyswitching must be immediately accessible and identifiable, and be capable ofcutting off the full load current.
Electrical machines must be provided with a means of emergency switching,and a person operating an electrically driven machine must have access to anemergency switch so that the machine can be stopped in an emergency.
Theremote stop/start arrangement could meet this requirement for an electricallydriven machine (IET Regulation 537.4.2.2). Devices which are suitable foremergency switching are switches, circuit-breakers and contactors.
Wherecontactors are operated by remote control they should open when the coil isde-energized, that is, fail safe. Push-buttons used for emergency switching mustbe coloured red and latch in the stop or off position.
They should be installedwhere danger may arise and be clearly identified as emergency switches.Plugs and socket outlets cannot be considered appropriate for emergencydisconnection of supplies.
Functional switching
involves the switching on or off, or varying the supply, ofelectrically operated equipment in normal service.The purpose of functional switching is to provide control of electrical circuits andequipment in normal service.Functional switching is for the user of the electrical installation or equipment.
The device must be capable of interrupting the total steady current of the circuitor appliance. When the device controls a discharge lighting circuit it musthave a current rating capable of switching an inductive load.
The regulationsacknowledge the growth in the number of electronic dimmer switches beingused for the control and functional switching of lighting circuits. The functionalswitch must be capable of performing the most demanding duty it may be calledupon to perform (IET Regulations 537.5.2.1 and 2)
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