Switch: Wikis

  
  

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.In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.^ In the fullness of time, I may come back and break it up, or write follow-on entries pontificating on one point or another, but for the nonce, your patience - and comments!

^ Component Switches(Multiple Sources, One TV) .
  • Switches & Splitters | BNC Splitters | Component & Matrix Switches 10 January 2010 0:15 UTC www.firefold.com [Source type: General]

[1][2] .The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts.^ One of the oldest, simplest, most generally effective debugging tools is some form of logging.

^ You may use two or more /AX switches to specify attribute bits to exclude files for file operations.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ The following switches check the destination directory ----- /I If the destination does not exist and you are copying more than one file, this switch assumes that the destination must be a directory (no prompting).
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

.Each set of contacts can be in one of two states: either 'closed' meaning the contacts are touching and electricity can flow between them, or 'open', meaning the contacts are separated and nonconducting.^ When you omit either the base_dir part or the pattern part, that is, when a source specifier without a backslash separating the two parts, the exact meaning of the command become ambiguous.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch. .Automatically-operated switches can be used to control the motions of machines, for example, to indicate that a garage door has reached its full open position or that a machine tool is in a position to accept another workpiece.^ You may use two or more /AX switches to specify attribute bits to exclude files for file operations.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ Note: /SP cannot be used with switches which reference the destination for file selection --- that is, the /Bxx (backup) switches, and /U will be disabled by /SP. That is, the spanning of the destination volume by /SP assumes the backup operation is a full backup without referencing the files already on the destination.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ The following switches control Move operations ----- /MVD Moves directories (the src and dst must be in the same volume).
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

.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.^ The following switches control Move operations ----- /MVD Moves directories (the src and dst must be in the same volume).
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ Or, you may use one /AX switch with multiple letters to exclude files with only the specified combination of attribute bits.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ The /FF switch is useful for incremental backup between volumes of different file systems.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

.For example, a thermostat is an automatically-operated switch used to control a heating process.^ The following switches control Move operations ----- /MVD Moves directories (the src and dst must be in the same volume).
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ You may use two or more /AX switches to specify attribute bits to exclude files for file operations.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ The following switches control List output ----- /L Same as /LLZ which performs the list operation (no file copy).
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

A switch that is operated by another electrical circuit is called a relay. .Large switches may be remotely operated by a motor drive mechanism.^ You may use two or more /AX switches to specify attribute bits to exclude files for file operations.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

.Some switches are used to isolate electric power from a system, providing a visible point of isolation that can be pad-locked if necessary to prevent accidental operation of a machine during maintenance, or to prevent electric shock.^ By isolating those circuits using generator power, a transfer switch eliminates the risk of back feeding the electrical utility, which can cause injury to workers and property damage.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

^ The /FF switch is useful for incremental backup between volumes of different file systems.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ It is the mission of Upper Canada Solar Generation to provide the best possible Solar Powered Generating Systems in a variety of sizes to suit all needs.

Three pushbutton switches (Tactile Switches). Major scale is inches.

Contents

Contacts

A toggle switch in the "on" position.
.In the simplest case, a switch has two pieces of metal called contacts that touch to make a circuit, and separate to break the circuit.^ All Raintight Pro/Tran transfer switches feature branch-circuit rated breakers, heavy-duty power inlet and non-defeatable (break-before-make) double-throw switches.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

.The contact material is chosen for its resistance to corrosion, because most metals form insulating oxides that would prevent the switch from working.^ Especially because the spice made it an unlikely match to most of the dishes being served (didn't work with the steak tartare, was not tasty with the salad dressing, etc).
  • Lever House Restaurant - Midtown East - New York, NY 2 February 2010 15:19 UTC www.yelp.com [Source type: General]

^ All of our installers and technicians are licensed to work with gas and propane and most hold additional licenses in sheet metal and refrigeration.

Contact materials are also chosen on the basis of electrical conductivity, hardness (resistance to abrasive wear), mechanical strength, low cost and low toxicity[3].
Sometimes the contacts are plated with noble metals. They may be designed to wipe against each other to clean off any contamination. Nonmetallic conductors, such as conductive plastic, are sometimes used.

Actuator

The moving part that applies the operating force to the contacts is called the actuator, and may be a toggle or dolly, a rocker, a push-button or any type of mechanical linkage (see photo).

Arcs and quenching

When the wattage being switched is sufficiently large, the electron flow across opening switch contacts is sufficient to ionize the air molecules across the tiny gap between the contacts as the switch is opened, forming a gas plasma, also known as an electric arc. The plasma is of low resistance and is able to sustain power flow, even with the separation distance between the switch contacts steadily increasing. .The plasma is also very hot and is capable of eroding the metal surfaces of the switch contacts.^ Thin Profile Magnetic Switch With Magnet THIN PROFILE Magnetic Switch SURFACE MOUNT CONTACT Screws or foam tape mounting.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

Where the voltage is sufficiently high, an arc can also form as the switch is closed and the contacts approach. .If the voltage potential is sufficient to exceed the breakdown voltage of the air separating the contacts, an arc forms which is sustained until the switch closes completely and the switch surfaces make contact.^ Thin Profile Magnetic Switch With Magnet THIN PROFILE Magnetic Switch SURFACE MOUNT CONTACT Screws or foam tape mounting.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

.In either case, the standard method for minimizing arc formation and preventing contact damage is to use a fast-moving switch mechanism, typically using a spring-operated tipping-point mechanism to assure quick motion of switch contacts, regardless of the speed at which the switch control is operated by the user.^ The following switches control Move operations ----- /MVD Moves directories (the src and dst must be in the same volume).
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ You may use two or more /AX switches to specify attribute bits to exclude files for file operations.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ (The third, in case you're wondering, is the pervasive use of open standards and non-proprietary technologies to help focus efforts on true innovation).

.Movement of the switch control lever applies tension to a spring until a tipping point is reached, and the contacts suddenly snap open or closed as the spring tension is released.^ Foot Switch-Close Out Sale SPST, normally open.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Switch it On or Off using a magnet with our miniature Reed Switch SPDT, normally open or Normally Closed.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

.As the power being switched increases, other methods are used to minimize or prevent arc formation.^ The following switches use other file attribute bits ----- /H Copies hidden and/or system files also.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ On the other hand, you may omit blank characters between switches in order to minimize the total length of the command line.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

A plasma is hot and will rise due to convection air currents. .The arc can be quenched with a series of nonconductive blades spanning the distance between switch contacts, and as the arc rises its length increases as it forms ridges rising into the spaces between the blades, until the arc is too long to stay sustained and is extinguished.^ On the other hand, you may omit blank characters between switches in order to minimize the total length of the command line.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

.A puffer may be used to blow a sudden high velocity burst of gas across the switch contacts, which rapidly extends the length of the arc to extinguish it quickly.^ You may use two or more /AT switches to specify multiple required attributes.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ You may use two or more /AX switches to specify attribute bits to exclude files for file operations.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ Alternatively, you may use one /AT switch with multiple letters to select alternative attribute bits to select files.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

.Extremely large switches in excess of 100,000 watts capacity often place the switch contacts in something other than air to increase the resistance against arc formation, such as enclosing the switch contacts in a vacuum, or immersing the switch contacts in mineral oil.^ I have seen short ribs at the 3 other restaurants we have dinned at for restaurant week so far, I am hopping that the two other places we go to next week will be trying something different on there menu.
  • Lever House Restaurant - Midtown East - New York, NY 2 February 2010 15:19 UTC www.yelp.com [Source type: General]

^ Automotive/Marine Toggle Switches Specifications: Current Rating: 20A-125V AC, 10A-250V AC* Insulation Resistance: 100 Megohms (min.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ PDF of Product Details [ PDF Help ] 5 Amps @125 VAC, 3 Amps @250 VAC Initial contact resistance: less than 50 milliohms Insulation resistance: > 100 Megohms @ 500 Volts.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

Contact arrangements

.
Triple Pole Single Throw (TPST or 3PST) knife switch used to short the windings of a 3 phase wind turbine for braking purposes.
^ Single Pole 12 position rotary switch Part#: ROT12 QTY: $ 1.00 [ NEW SURPLUS/OVERSTOCK ITEM-LIMITED QUANTITIES AVAILABLE ] .
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

Here the switch is shown in the open position.
A pair of contacts is said to be "closed" when current can flow one to the other. When the contacts are separated by an insulating air gap, an air space, they are said to be 'open', and no current can flow at typical voltages.
Switches are classified according to the arrangement of their contacts in electronics. .Electricians installing building wiring use different nomenclature, such as "one-way", "two-way", "three-way" and "four-way" switches, which have different meanings in North American and British cultural regions as described in the table below.^ I'll likely come back and revisit it later, breaking it up into two or three smaller ones.

^ The /FF switch is useful for incremental backup between volumes of different file systems.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ Real standards happen in one of two ways.

Some contacts are normally open (Abbreviated "n.o." or ."no") until closed by operation of the switch, while others are normally closed ("n.c.^ The following switches control List output ----- /L Same as /LLZ which performs the list operation (no file copy).
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

or "nc"
) and opened by the switch action.
A switch with both types of contact is called a changeover switch. .These may be "make-before-break" which momentarily connect both circuits, or may be "break-before-make" which interrupts one circuit before closing the other.^ In the fullness of time, I may come back and break it up, or write follow-on entries pontificating on one point or another, but for the nonce, your patience - and comments!

^ All Raintight Pro/Tran transfer switches feature branch-circuit rated breakers, heavy-duty power inlet and non-defeatable (break-before-make) double-throw switches.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

^ The balance of the circuit breakers are single-pole 15A. The 15A circuits in the transfer switch may be connected to 15A or 20A circuits in the load center.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

.The terms pole and throw are also used to describe switch contact variations.^ It's funny because when I try to describe my first impressions and the taste, the same terms I used to describe the atmosphere come to mind--elegant, classy and reserved.
  • Lever House Restaurant - Midtown East - New York, NY 2 February 2010 15:19 UTC www.yelp.com [Source type: General]

.A pole is a set of contacts and terminals that are connected to a single circuit.^ The balance of the circuit breakers are single-pole 15A. The 15A circuits in the transfer switch may be connected to 15A or 20A circuits in the load center.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

^ The spaces containing the 30A and 20A double-pole circuits may be replaced with 15 or 20A single-pole breakers if desired.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

^ AMP SINGLE POLE CIRCUIT BREAKERS .
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

A throw is one of two or more positions that the switch can adopt. A single-throw switch has one position that closes contacts, a double-throw switch has two position, and so on.
.These terms give rise to abbreviations for the types of switch which are used in the electronics industry such as "single-pole, single-throw" (SPST) (the simplest type, "on or off") or "single-pole, double-throw" (SPDT), connecting either of two terminals to the common terminal.^ So, besides the obvious compulsive hackers and the people building single-purpose appliance-type systems, who would really make use of this?

^ You may use two or more /AT switches to specify multiple required attributes.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

^ You may use two or more /AX switches to specify attribute bits to exclude files for file operations.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

In electrical power wiring (i.e. House and building wiring by electricians) names generally involving the suffixed word "-way" are used; however, these terms differ between British and American English and the terms two way and three way are used in both with different meanings.
Electronics specification and abbreviation Expansion
of
abbreviation
British
mains
wiring
name
American
electrical
wiring
name
Description Symbol IEC 60617
SPST Single pole, single throw One-way Two-way A simple on-off switch: The two terminals are either connected together or disconnected from each other. An example is a light switch. SPST-Switch.svg Symbol circuit breaker (one-pole).svg
SPDT Single pole, double throw Two-way Three-way A simple changeover switch: C (COM, Common) is connected to L1 or to L2. SPDT-Switch.svg Symbol change over switch.svg
SPCO
SPTT, c.o.
Single pole changeover
or
Single pole, centre off or
Single Pole, Triple Throw
    Similar to SPDT. .Some suppliers use SPCO/SPTT for switches with a stable off position in the centre and SPDT for those without.^ As some of you know, I'm working on a book on Web development, using off-the-shelf tools (frameworks, template engines, JavaScript libraries, etc.

^ Note: /BS for copy usually accomplishes nothing but is useful as /RS/BS. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Source Specifier: XXCOPY's first argument (without regard to command switches) is the source specifier.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

[citation needed]
   
DPST Double pole, single throw Double pole Double pole Equivalent to two SPST switches controlled by a single mechanism DPST-symbol.svg Symbol circuit breaker (two-pole).svg
DPDT Double pole, double throw     Equivalent to two SPDT switches controlled by a single mechanism: A is connected to B and D to E, or A is connected to C and D to F. DPDT-symbol.svg Symbol change over switch (two-pole).svg
DPCO Double pole changeover
or Double pole, centre off
    Equivalent to DPDT. .Some suppliers use DPCO for switches with a stable off position in the centre and DPDT for those without.^ Switch it On or Off using a magnet with our miniature Reed Switch SPDT, normally open or Normally Closed.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Can not turn switch on (or Off) without first flipping up the safety switch cover.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ As some of you know, I'm working on a book on Web development, using off-the-shelf tools (frameworks, template engines, JavaScript libraries, etc.

    Intermediate switch Four-way switch DPDT switch internally wired for polarity-reversal applications: only four rather than six wires are brought outside the switch housing; with the above, B is connected to F and C to E; hence A is connected to B and D to C, or A is connected to C and D to B. Crossover-switch-symbol.svg Symbol cross switch.svg
.Switches with larger numbers of poles or throws can be described by replacing the "S" or "D" with a number or in some cases the letter "T" (for "triple").^ Since the number of switches far exceeds the number of letters available in the alphabet, many of the switches use multiple characters.
  • XXCOPY Command Parameters Reference 10 January 2010 0:15 UTC www.xxcopy.com [Source type: Reference]

In the rest of this article the terms SPST, SPDT and intermediate will be used to avoid the ambiguity in the use of the word "way".

Biased switches

A biased switch is one containing a spring that returns the actuator to a certain position. .The "on-off" notation can be modified by placing parentheses around all positions other than the resting position.^ As far as I am aware, every other major graphical browser in the world - Firefox , Opera , Konqueror , Galeon and the rest - all support The Right Thing.

For example, an (on)-off-(on) switch can be switched on by moving the actuator in either direction away from the centre, but returns to the central off position when the actuator is released.
The momentary push-button switch is a type of biased switch. .The most common type is a "push-to-make" (or normally-open or NO) switch, which makes contact when the button is pressed and breaks when the button is released.^ Foot Switch-Close Out Sale SPST, normally open.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Switch it On or Off using a magnet with our miniature Reed Switch SPDT, normally open or Normally Closed.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Magnetic Switch for doors or other apertures SPST, normally open.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

.Each key of a computer keyboard, for example, is a normally-open "push-to-make" switch.^ Foot Switch-Close Out Sale SPST, normally open.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Switch it On or Off using a magnet with our miniature Reed Switch SPDT, normally open or Normally Closed.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Magnetic Switch for doors or other apertures SPST, normally open.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

.A "push-to-break" (or normally-closed or NC) switch, on the other hand, breaks contact when the button is pressed and makes contact when it is released.^ The other is momentary and the switch will be closed only as long as the user keeps the switch pressed down with his foot.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Foot Switch-Close Out Sale SPST, normally open.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

^ Switch it On or Off using a magnet with our miniature Reed Switch SPDT, normally open or Normally Closed.
  • Switches, Toggle Switches, Rocker Switches, Push Button Switches, Foot Switches 10 January 2010 0:15 UTC www.action-electronics.com [Source type: FILTERED WITH BAYES]

An example of a push-to-break switch is a button used to release a door held open by an electromagnet.

Special types

Switches can be designed to respond to any type of mechanical stimulus: for example, vibration (the trembler switch), tilt, air pressure, fluid level (the float switch), the turning of a key (key switch), linear or rotary movement (the limit switch or microswitch), or presence of a magnetic field (the reed switch).

Mercury tilt switch

The mercury switch consists of a drop of mercury inside a glass bulb with 2 or more 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.
This type of switch performs much better than the ball tilt switch, as the liquid metal connection is unaffected by dirt, debris and oxidation, it wets the contacts ensuring a very low resistance bounce-free connection, and movement and vibration do not produce a poor contact. These types can be used for precision works.
It can also be used where arcing is dangerous (such as in the presence of explosive vapour) as the entire unit is sealed.

Knife switch

Knife switches consist of a flat metal blade, hinged at one end, with an insulating handle for operation, and a fixed contact. When the switch is closed, current flows through the hinged pivot and blade and through the fixed contact. Such switches are usually not enclosed. The parts may be mounted on an insulating base with terminals for wiring, or may be directly bolted to an insulated switch board in a large assembly. Since the electrical contacts are exposed, the switch is used only where people cannot accidentally come in contact with the switch.
.Knife switches are made in many sizes from miniature switches to large devices used to carry thousands of amperes.^ Any device, from large mainframes to appliances to mobile phones, can be used to produce or access information via HTTP, most commonly in the form of Web pages.

.In electrical transmission and distribution, gang-operated switches are used in circuits up to the highest voltages.^ By isolating those circuits using generator power, a transfer switch eliminates the risk of back feeding the electrical utility, which can cause injury to workers and property damage.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

The disadvantages of the knife switch are the slow opening speed anparts. .Metal-enclosed safety disconnect switches are used for isolation of circuits in industrial power distribution.^ By isolating those circuits using generator power, a transfer switch eliminates the risk of back feeding the electrical utility, which can cause injury to workers and property damage.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

^ Determining which circuits you will require during a power outage is the first step in selecting the proper wattage generator and transfer switch.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

Sometimes spring-loaded auxiliary blades are fitted which momentarily carry the full current during opening, then quickly part to rapidly extinguish the arc.

Intermediate switch

.A DPDT switch has six connections, but since polarity reversal is a very common usage of DPDT switches, some variations of the DPDT switch are internally wired specifically for polarity reversal.^ Power Savings by Cable Length D-Link Green verified switches have the ability to analyze the length of any Ethernet cable connected to them for adjustment of power usage accordingly.
  • D-Link 5-Port 10/100/1000 Desktop Switch 10 January 2010 0:15 UTC www.dlink.com [Source type: General]

^ Then select the load center circuits needed in an emergency and connect them to the wires leads from the transfer switch.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

^ The Pro/Tran manual transfer switch is specifically designed to connect your portable generator to the circuit breaker panel in your home.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

These crossover switches only have four terminals rather than six. Two of the terminals are inputs and two are outputs. When connected to a battery or other DC source, the 4-way switch selects from either normal or reversed polarity. .Intermediate switches are also an important part of multiway switching systems with more than two switches (see next section).^ But it does nicely sum up, more effectively and efficiently than I have been able to of late, the reasons why Apple is important as a force in the technology business.

^ While the justification for this exists in the current American social and political system, more than ever before in living memory....

^ On another, equally but not always obviously important level, more than enough rope for you to shoot yourself in the foot .

Light switches

In building wiring, light switches are installed at convenient locations to control lighting and occasionally other circuits. .By use of multiple-pole switches, control of a lamp can be obtained from two or more places, such as the ends of a corridor or stairwell.^ But if you run multiple computers and need quick access to them, a KVM can prove very handy by letting you use just one monitor, one keyboard and one mouse to control two or more systems.
  • switches | ITworld 10 January 2010 0:15 UTC www.itworld.com [Source type: General]

Power switching

.When a switch is designed to switch significant power, the transitional state of the switch as well as the ability to stand continuous operating currents must be considered.^ Well-guarded state transitions?

^ Transfer switches are the key to safe and convenient operation of portable generators for standby power.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

When a switch is in the on state its resistance is near zero and very little power is dropped in the contacts; when a switch is in the off state its resistance is extremely high and even less power is dropped in the contacts. However when the switch is flicked the resistance must pass through a state where briefly a quarter (or worse if the load is not purely resistive) of the load's rated power is dropped in the switch.
.For this reason, most power switches (most light switches and almost all larger switches) have spring mechanisms in them to make sure the transition between on and off is as short as possible regardless of the speed at which the user moves the rocker.^ Higher energy production, at lower wind speeds, with less noise make VAWTs perfect for most urban and rural applications.

^ And the App Store, by almost any measure, is a raging success in the aggregate — even though most individual developers aren't making much at all.

^ All models without a power inlet on the front include a covered opening that permits the installation of a power inlet for cord connection directly to the transfer switch.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

Power switches usually come in two types. .A momentary on-off switch (such as on a laser pointer) usually takes the form of a button and only closes the circuit when the button is depressed.^ Circuits are limited to 15A only on the generator side of the switch.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

A regular on-off switch (such as on a flashlight) has a constant on-off feature. Dual-action switches incorporate both of these features.
A diagram of a dual-action switch system

Inductive loads

When a strongly inductive load such as an electric motor is switched off, the current cannot drop instantaneously to zero; a spark will jump across the opening contacts. .Switches for inductive loads must be rated to handle these cases.^ Since many portable generators cannot handle all of these loads at the same time, the transfer switch allows you to manually transfer each of these loads separately whenever you need them or as required.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

The spark will cause electromagnetic interference if not suppressed; a snubber network of a resistor and capacitor in series will quell the spark.

Contact bounce

Contact bounce (also called chatter) is a common problem with mechanical switches and relays. Switch and relay contacts are usually made of springy metals that are forced into contact by an actuator. When the contacts strike together, their momentum and elasticity act together to cause bounce. The result is a rapidly pulsed electrical current instead of a clean transition from zero to full current. The effect is usually unimportant in power circuits, but causes problems in some analogue and logic circuits that respond fast enough to misinterpret the on-off pulses as a data stream[4].
Sequential digital logic circuits are particularly vulnerable to contact bounce. .The voltage waveform produced by switch bounce usually violates the amplitude and timing specifications of the logic circuit.^ The Pro/Tran manual transfer switch is specifically designed to connect your portable generator to the circuit breaker panel in your home.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

The result is that the circuit may fail, due to problems such as metastability, race conditions, runt pulses and glitches.
.The effects of contact bounce can be eliminated by use of mercury-wetted contacts, but these are now infrequently used because of the hazard of mercury release.^ These can be dirt simple; I use Dokuwiki , and have for over a year now.

Contact circuits can be filtered to reduce or eliminate multiple pulses. In digital systems, multiple samples of the contact state can be taken or a time delay can be implemented so that the contact bounce has settled before the contact input is used to control anything. One way to implement this is by using an SR Latch.[5]

Electronic switches

.Since the advent of digital logic in the 1950s, the term has spread to a variety of digital active devices such as transistors and logic gates whose function is to change their output state between two logic levels or connect different signal lines, and even computers, network switches, whose function is to provide connections between different ports in a computer network.^ As many people have pointed out, the iPad differs in one critical respect from every personal computing device as computing device that Apple have ever built, from the Apple I on up to the iMac that I am typing this on.

^ Instead of making copies of each version of a binary file, all that is required is to take the difference between two different versions of a text file - a much easier and more reliable operation.

^ Because, even though this is a "real" computer, it's "really not"; it's an up-sized iPod Touch, which is (officially, mostly) a passive device.

[6] .The term 'switched' is also applied to telecommunications networks, and signifies a network that is circuit switched, providing dedicated circuits for communication between end nodes, such as the public switched telephone network.^ His short-term goal is to act as a liaison between Queen’s and the SWITCH community.

.The common feature of all these usages is they refer to devices that control a binary state: they are either on or off, closed or open, connected or not connected.^ Another bonus to all of this is that all of these applications involve databases, with most of the information being text or (hopefully) relatively small binary files.

^ All models without a power inlet on the front include a covered opening that permits the installation of a power inlet for cord connection directly to the transfer switch.
  • Generator Transfer Switches by Reliance Controls. 17 September 2009 21:20 UTC www.emergencypower.com [Source type: FILTERED WITH BAYES]

^ To top it all off, at the end for petit fours they gave us chai cookies with a white chocolate top.
  • Lever House Restaurant - Midtown East - New York, NY 2 February 2010 15:19 UTC www.yelp.com [Source type: General]

References

  1. ^ "Switch". The Free Dictionary. Farlex. 2008. http://www.thefreedictionary.com/switch. Retrieved 2008-12-27. 
  2. ^ "Switch". The American Heritage Dictionary, College Edition. Houghton Mifflin. 1979. pp. 1301. 
  3. ^ "General Electric Contact Materials". Electrical Contact Catalog (Material Catalog). Tanaka Precious Metals. 2005. http://www.tanaka-precious.com/catalog/material.html. Retrieved 2007-02-21. 
  4. ^ Walker, PMB, Chambers Science and Technology Dictionary, Edinburgh, 1988, ISBN 1852961503
  5. ^ http://www.ganssle.com/debouncing.pdf
  6. ^ "'Switch'". Telecom definitions. SearchTelecom.com. 2007. http://searchtelecom.techtarget.com/sDefinition/0,,sid103_gci213079,00.html. Retrieved 2008-12-27. 

See also

External links


Simple English

File:Light switch inside
A light switch, with explanations
File:Swe subway switch 20050425
A switch in a train system (here a subway)

A switch is something that changes the flow of an electrical circuit. The most common kind of switch is a something (for example a railroad switch) which can be taken off of one course and put on to another. The term "switch" usually means electrical power. In applications where more than one switch is needed, (i.e. a telephone service) mechanical switches have been replaced by electronic switches which can be controlled automatically.

The switch is called a "gate" when used in a mathematical form. In logic, arguments are represented as logic gates. The use of electronic gates to work as a system of logical gates is the basic idea behind the computer —ie. a computer is a lot of electronic switches that work as logic gates.


Citable sentences

Up to date as of December 24, 2010

Here are sentences from other pages on Switch, which are similar to those in the above article.








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