Distribution of electrics and electronics










AC : Alternating current; electric current that continually reverses direction at a fixed frequency (see VAC).

ACTUATION FORCE : (Operating Force) : The force required to change the actuator of a switch from one position to another. Torque for rotary products.

ACTUATOR : A movable part of a switch which causes a change in the electrical configuration of the switch. e.g. : Toggle, Rocker, Slider, Paddle, Pushbuttons, Shaft

ALLOY : A metal created by combining two or more metals to obtain a specific physical property

ALTERNATE ACTION : Push to close and push to open the switch. A given circuit condition remains after removal of actuating force. Also known as "pushpush switching action". Typically, alternate action pushbuttons do not visually indicate the position of the contacts. Contrast to latching action.

ANGLE OF THROW : Indicates total travel arc on toggle or rocker switches. Unit of measure : degrees

ANTISTATIC : An antistatic device will withstand a specified potential without conducting between the actuator and any conducting element. Usually the terminals or bushing. Unit of measure : typical value 8-20 kilovolts DC.

ANSI : American National Standard Institute; a standard-setting agency of the United States which approves the design and/or performances of electronic/electrical components distributed in the world market.

ARCING : The flow of electric current between switch contacts during opening or closing of the contacts. This current flow can be damaging to the contacts of a switch.

BIFURCATED CONTACT : A wiping movable contact consisting of spring fingers that grip fixed contacts. Typically found in slide switches. Self cleaning action. See Wiping Contact.

BOUNCE : The repeated rebounding of the moveable contact during the transfer from one throw to the next.

BRASS : An alloy of zinc and copper

BREAK-BEFORE-MAKE (Non shorting - B.B.M.) : On actuation, the movable contact breaks contact with one fixed contact before making contact with another fixed contact. Contrast with make-before break. Typical of toggle and pushbutton switches.

BUTT CONTACT : A contact mechanism in which the movable contact makes contact with the fixed (stationary) contact without wiping motion between the surfaces. Typical of toggle and pushbutton switches. See Wiping Contact.

CAPACITIVE LOAD : A load in which the initial current on making (closing) of the contacts is higher than the steady state current. Current leads voltage in capacitive loads. See Resistive Load, Inductive Load, Power Factor, Inrush.

CARRYING CURRENT : The maximum current that can be passed through the already closed contacts of a switch.Contrast with "Contact Rating".

CLEARANCE (spacing) : Distance through air between electrically live parts of opposite polarity or to ground.

CONTACT (Contact area) : The metal surfaces that come into physical contact to complete an electrical circuit. These surfaces are found on movable contacts (see) and terminals (see).

CONTACT BLOCK : A switching element which is added singly or in groups to an operator to make a complete switch. Typically used with industrial controls (APEM A01 and A02 series).

CONTACT BOUNCE (Bounce) : The time during switching in which electrical instability (bounce) caused by the rebound of the contacts is observed. Relative mass of the contacts, forces and frequency of supporting members are all components that determine the extent of bounce. Total transfer time consists of the time for the contacts to close plus bounce. Transfer time should be rapid so natural bounce time is short.

CONTACT GAP : The distance between a stationary contact and a movable contact in the open position.

CONTACT RATING (Switching rating) : The capacity to switch (connect or interrupt) an electrical load. Load characteristic (resistive, inductive, capacitive, power factor). Contrast with non-switching rating.

CONTACT RESISTANCE : The resistance across the two closed contacts : contact interface and terminals.

CREEPAGE : The unwanted flow of electrical current from one conductive part to another.

CSA : Canadian Standard Association

CYCLE : The complete sequence of indexing through all successive switch positions and returning to the original position.

DC : Direct Current : electric current that flows only in one direction (see VDC).

DETENT : A mechanical stop that holds the contacts in a given position after the actuation force is removed or prevents the changing of contact position at less than a specified actuation force. Can also be referred to as tactile feel.

DIELECTRIC STRENGTH : The ability of an insulating material to withstand a voltage without arcing across its surface. The standard voltage that can be applied between two open terminals or between a terminal and ground without causing short. Most often applied to insulator between switch terminals and metal exposed to operator of the switch. Also known as Dielecric Withstanding Voltage, DWV, Leakage resistance, Breakdown Voltage.

DIFFERENTIAL TRAVEL : The distance an actuator moves between the point where contacts snap over and where they snap back, or when contact is made and then brakes.

DIP : DIP-in-line Package (in Europe also, DIL : Dual-in-line) refers to a component with two rows of PC terminals. The terminals are most commonly on a 0,100" pitch with 0,300" between rows.

DOUBLE-BREAK CONTACTS : A contact mechanism using two sets of contacts to make or break a given circuit. The contact gap opens twice as fast, reducing the arc duration, contact surface temperature and material erosion. This improves heat dissipation and provides better power handling capacity for a longer switch life. Typical of high power industrial switches and DC Circuit application. See Single-Break Contacts.

DP : Double pole. See pole.

DRY CIRCUIT : An application in which power level do not cause arcing melting, or softening of the contacts . Typically requires gold plated contacts for reliable switch operation. At such low levels, and since no arc occurs, silver contacts would not be self-cleaned and would be less reliable. Typical Definition : for ex. 0.4VA max. 20 V DC or peak AC max. Also known as "Low Energy", "Logic Level", TTL.

DWV : Dielectric Withstanding Voltage. See Dielectric Strength.

DT : Double Throw. See Throw.

DUST TIGHT : Sealed switch will withstand sand and dust contamination.

ELECTRICAL LIFE : The number of operations at a given electrical load that does not result in a degradation of any electrical or mechanical parameter beyond the standard set by the applicable end-of-life criteria.

END OF LIFE CRITERIA : Those specifications that a switch must meet at the end of its specified electrical life. Typically contact resistance and/or heat rise of contacts at full rated load at end of life.

ENVIRONMENTAL SEAL : A seal that totally encapsulates the switch providing a specified level of protection against intrusion of solids, liquids or gases into the body of the device.

ESD : Electrostatic discharge.

FIXED CONTACT (Stationary contact) : The non-moving contact. Typically integral to the end of the terminal inside the switch body.

FLASH PLATING : A very thin or "instant" plating (usually less than 0.25 microns in thickness).

FLUX : Chemical used for cleaning metal surfaces for welding. Fluxes turn contaminated metal surfaces into clean, solderable part.

GOLD FLASH : A plating of gold typically less than 10 micro-inches (milliononths) thick. Used only as a barrier to oxidation or corrosion of terminals to maintain solderability.

GULL WING : A type of surface mount terminal which extends from the side of the switch and has a L-shaped bend at its end (terminals are formed away from the switch body).

HEAT RISE : An indirect measurement of contact resistance used by rating agencies. The temperature rise over ambient of a contact set carrying a prescribed current is measured to determine whether it falls within safe limits.

IEC : International Electrotechnical Commission

IECQ : IEC's Quality Assessment system for Electronic Components, created in 1983 to facilitate national and international trade in certified electronic components. A worldwide certification system which provides a method whereby electronic components made and handled by approved manufacturers and distributors can be used anywhere without further testing.

INDUCTIVE LOAD : A load in which the initial current on making (closing) of the contacts is lower than steady state and rises slowly. On breaking (opening) of the contacts, the current is greater than steady state. The stored energy of the inductor provokes a long and severe arcing time. Current lags voltage in inductive loads. Motors are the most common inductive load. Inductive loads are the most troublesome of circuit conditions. See Resistive Load. Capacitive Load.

INFRARED REFLOW : A method of mass soldering Surface Mount Devices with Infra Red (IR) thermal radiation heating the PCB solder paste and components.

INRUSH : The initial transitory high-level of current at contact closing (making). A characteristic of capacitive and some resistive loads. The inrush currents can be large and long enough to cause severe degradation of the contacts. See Resistive Load. Capacitive Load. Power Factor.

INSERT MOLD : In switches and relays used to refer to terminations that are placed in the mold so that plastic is molded around the terminations. The chief benefit is an inherent seal against the intrusion of flux into the body of the device. Therefore no epoxy terminal seal is required.

INSULATION RESISTANCE : The electrical resistance between two normally insulated parts measured at a specified DC voltage.

IP : An industrial specification (Part of the IEC529 standard) used worldwide to indicate the degree of protection provided by components against accidental contact, penetration of solids or liquids into or through the component.See NEMA.

LAMP LOAD (Tungsten) : A load characterised by a high inrush current at make (approximately 10 to 16 times the steady state).

LATCHING ACTION : See alternate action (or push-push). Actuator position typically indicates contact position.

LEAKAGE BARRIER : A ridge or web molded into a switch housing between terminals or contacts to increase the surface distance between them.

LEAKAGE RESISTANCE : Dielectric strength

LED : Light Emitting Diode. Long life and low consumption illumination

LIFE : See Electrical life, Mechanical Life.

LOGIC LEVEL : Refers to power levels typical of solid state electronic circuits (TTL, CMOS, etc.). Levels at which no arcing, melting or softening of the contacts occur. Typically require gold contacts for reliability since no arcing occurs to self clean the contacts. See Dry circuit. Also referred to as low energy

LOW ENERGY : See Dry circuit.

MAINTAINED : A position of a switch which remains unchanged when actuation force is removed from switch actuator. Contrast with Momentary.

MAKE-BEFORE-BREAK (shorting, MBB) : Movable contacts make the next circuit before breaking the first circuit. Typically found in slide switches. Contrast with Break-before-make.

MAKE AND BREAK : Opening one circuit before completing another on the same pole

MECHANICAL LIFE : The number of operations of a switch without electrical load that does not result in a degradation of parameters beyond the standard set by the applicable end-of-life criteria.

MOISTURE PROOF : Sealed switch will withstand high humidity and limited exterior environment such as rain.

MOMENTARY ACTION : Mechanically returning from a temporary switch position to the normal switch position

MOVABLE CONTACT : The contact moved by the switch actuator into and away from contact with a fixed contact thus forming the electrical circuits possible for a given device.

NEMA : National Electrical Manufacturers' Association. A US Standards setting group. For switch products most often applied to switches mounted in various enclosures offering specified degrees of protection against intrusion of liquids, dust, corrosive elements, etc. NEMA ratings are common in industrial or outdoor applications. See IP.

NO : See Normally Open.

NON-SHORTING : See Break-Before-Make

NON-SWITCHING RATING : The power carring capacity of a switch after contact closure and end of contact bounce. Typically far higher than the contact rating (switching rating) of a switch.

NORMALLY CLOSED (NC) : Normally closed contacts are closed when the switch actuator is in its unactuated position (e.g., the plunger is in the resting position in the case of a pushbutton switch).

NORMALLY OPEN (NO) : Normally open contacts are open when the switch actuator is in its unactuated or resting position.

OIL-TIGHT : A generic term for a panel seal (see) commonly used in industrial settings. Defined by NEMA (see) standard.

OPEN FRAME : Typical to slide switches ; open frame construction allows for automatic solder process and post solder cleaning. Contrast with "washable".

OPERATING FORCE : See Actuation Force.

OPERATING TEMPERATURE : The range of temperature within which the device may be used.

OPERATOR : A panel-mounted mechanical device (pushbutton, selector, keylock, etc.) without contacts to which one or more contact blocks may be added to make a complete switch (See APEM A01-A02 Series).

OVERTRAVEL : The distance the actuator may move between initial electrical contact position and the extreme mechanical position of the actuator. See Travel, Pretravel.

PANEL SEAL : A panel seal provides a defined level of protection against penetration of liquids through the switch and switch-to-panel interface to the rear of a panel.

PCB : Printed circuit board

POLE : Single common electrical input having one or more outputs. The number of seperate circuits that can be active through a switch at any one time. A singlepole switch allows one closed circuit at a time. A double-pole switch allows two closed circuits, etc.

POWER FACTOR (PF) : A measure of the inductive or capacitive character of an electrical load.

PRETRAVEL : The distance the actuator moves from a rest position (or free position) to electrical make at another position. See Travel, Overtravel.

PUSH-ON / PUSH-OFF : See Alternate Action.

PUSH-PUSH : See Alternate Action.

QUICK-CONNECT TERMINAL : Flat tab or blade style terminals designed to accept push-on female wire connectors (instead of soldering). The most popular sizes are : 0.250". 0.187". 0.110" wide.

RATING : See contact rating

RESISTIVE LOAD : Current and voltage are in steady state on opening or closing the switch. See capacitive load, Inductive load, Power factor, Inrush.

SEMKO : Svenska Elektriska Materielkontrollanstalten of Sweden

SEV : Schweizerischer Elektrotechnisher Verein of Switzerland

SHORTING CONTACT : Contacts which make-before-break. See Make-before-Break

SILICON RUBBER : Rubber made from silicone elastomers which keeps its high level of flexibility, resilience and tensile strength over a wide temperature range.

SINGLE BREAK CONTACTS : A contact mechanism using one set of contacts to make or break a given circuit. Typical of electronic or low power switches. See Double-Break Contacts.

SNAP ACTION : The fast transfer of contacts from one position to another, this action is rather independent of the speed of actuator travel

SPACING : See Clearance

SPDT : Single pole double throw. See Pole, See Throw.

SPLASHPROOF : Sealed switch will withstand heavy rain or stream of water. See Panel Seal.

SPRING RETURN : See momentary.

STORAGE TEMPERATURE : The range of temperature within which the device may be stored. Typically this is a wider range than operating temperature.

SURFACE MOUNT DEVICES (SMD) : Components that are compatible with surface mount PC board technology. Holes are not used for component mounting. Component leads are soldered to pads on the surface of the PC board (on the same side as the components). For switches, typically defined by surface mount terminations (e.g., J-Bend. L-Bend, butt, etc.) and compatibility with surface mount soldering (e.g., vapor phase reflow, infrared, etc.) and cleaning processes.


TACTILE FEEL (FEEDBACK) : The switching action felt by the operator of the switch (same as click action or positive action). Audible or "feel" snap or click that indicates contact movements.

TERMINAL : The metal portion of a switch, exterior to the body, that is used to connect the switch to an electrical circuit. Example : PC, wire lug, quick-connect, wire-wrap, etc.

THROW : The number of circuits that can be controlled by any one pole of a switch. Example : In a single-pole-double-throw (SPDT) switch, only one circuit may be completed at a time. However, there are two possible circuits (throws) that can be made.

TRANSLUCENT : Transmitting light so that objects lying beyond cannot be seen distinctly.

TRANSPARENT : Transmitting light so that objects lying beyond can be seen distinctly.

TRAVEL : The total distance the actuator can move. See Pretravel, Overtravel.

TWO CIRCUITS : A circuit in which one circuit is completed in one position and another separate circuit is completed in an other position.

UL : Underwriters laboratories Inc.

VAC : Voltage, alternating current (see AC)

VDC : Voltage, direct current (see DC)

VDE : Verband Deutscher Elektrotechniker of Germany

WASHABLE : Applied to PC board mounted devices indicating compatibility with cleaning processes used after soldering. No degradation of electrical or mechanical parameters occurs. The switch is sealed to keep contaminents out of the contact area.

WAVE SOLDERING : A method of soldering in which a wave of molten solder contacts the components on the PCB as the PC Board with the components is conveyed through the process.

WIPING ACTION : Sliding of contacts over one another resulting in cleaning of the contacts.

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