Index


Electronics connector information

Basics

Connectors are devices, either plugs or receptacles, used to terminate or connect the conductors of single-conductor or multiple- conductor cables, and provide a means to continue the conductors to a mating connector or printed circuit board. It is a device that connects wires or fibers in cable to equipment or other wires or fibers. Wire and optical connectors most often join transmission media to equipment or cross connects. There are many classes of connectors. Mainly the categories are based on shape, function and smallest size contact in the series. Shapes can be cylindrical, rectangular, keystone, etc. Functions or applications can be hermetic, rack-and-panel, pendant, bulkhead, firewall, feed thru, power, computer, fibre channel, skis, etc.

In general, connectors for high voltage use are to be chosen such that they are incompatible with connectors for signal cables.

Connector components properly rated for the intended application shall be used.

Insulation for wiring used in electronics is critical for safety and performance. The proper insulation is also essential in connectors.

Soldering versus criped connector selection: Crimped contacts (rather than soldered) are less susceptible to bending fatigue failures. That type of failure occurs because the solder forces the stranded conductor to become solid at the joint. Connectors are frequently flexed and sometimes pulled by their cable which causes subtle bending and flexing at the contact joint. Crimped joints hold up to this flexing better than soldered joints.

The world of power connectors has been perceived as a relatively stable product segment, dominated by a few suppliers and enjoying little of the glamour of interfaces targeted at high speed / high performance or I/O applications. Today???s system emphasis on greater power consumption has sparked new life into the power connector market, which may be poised to gain greater respect as well as early design consideration in the new product design cycle.

Usually designers have to choose connectors conservatively, keeping in mind the principles.

Basics for connector specifications

Typical connector specifications:

  • Connector size
  • Connector shape
  • Number of pins in connector
  • Mechanical strength
  • Current capacity
  • Working current
  • Voltage rating
  • Working voltage
  • Insulation rating (resistance)
  • Mechanical working life (number of mating cycles)
  • Connector environmental protection (can connector withstand wet condition, can it withstand outside condition, UV radiation, chemicals etc.)
  • Connector touch protection (can user touch connector electricity carrying parts if the connector is connected/disconnected)
  • The order of parts in connector makes connection (for example in certain connectors shield connects forst, then ground pins, then signals)
  • Reliabity (Reliability is the probability that a part will perform as required for a desired 'time' during which it is subjected to a given set of environmental and/or mechanical stresses.)
  • Connector price

Connector current ratings seem to be shrouded in mystery at times. The user wonders how a listed current rating is relevant to a particular application. Perhaps more mysterious is how similar connectors from various manufacturers list different current rating values. While it is true that material choice and design can enhance a connector???s current rating, the test method by which the rating was developed must be understood when evaluations are made. A wide variety of test methods are employed in order to develop current ratings for connectors. Some of these methods come from standards that are recognized industry wide, while others are unique to the manufacturer or user. These various test methods can produce different results for the same product. It is no wonder confusion sometimes results. Current ratings are usually established by first developing a temperature rise curve. This curve plots temperature rise against increasing current levels. The curve is a reliable tool in understanding heat generation of the connector at various currents. When a defined failure is reached, the test ends. The highest current level achieved is usually listed as the current rating. Clearly a current rating value alone is not enough, and must be viewed in the context of the test used to develop the rating. When the test method is understood, evaluating and comparing power connectors for specific applications becomes much less of a mystery. When looking at the current rating make also sure how manufacturer has specificied it, usually it is per pin, but there can be also limitations of total current or told current it total current for connector.

Universal signal / data connectors

    D connectors

    The most commonly used low voltage data connectivity connector series is the D connector series. It is a connector with an odd number of pins put to a D letter shaped frame in two rows. The connectors are typically available different numers of pins from 9 pins up to 50 pins. Most commonly seen connector models have 9, 15, 25 or 37 pins. Also other versions exist. Typical current rating is 1-5 ampreres and voltage rating typically 125V (I have also seen 3000-350V and 7.5A current rated versions . Typically the version that mount to PCB has around 1 amprere current rating, while the version that go directly to wires have 3-5 ampere current ratings.

    NOTE: There is als a D-connector variation that has three rows of pins (usually called high density D connector, usually marked with HD).

    Typical applications for D-connectors include the following: RS-232 interfaces (D9, D25), RS-485 interfaces (D9, D15), other computer serial port interfaces, computer VGA port (HD15)

    D connectors are genreally available also as IDC TYPE for easy, no soldering use. IDC type snaps onto a ribbon cable.

    • D-sub connector info from Hirose    Rate this link
    • D-Sub Connectors Information - A range of standard connectors, widely used on PCs and elsewhere. Available in mating male and female versions in 9, 15, 25 and 37-way. Gold over nickel-plated copper alloy contacts identified on both sides of the PBT and glass fibre reinforced moulding (UL-94-V0). Solder cup terminations. Designed for chassis mounting or making into line connectors with the use of the appropriate hood. Working current 7.5A per contact and working voltage 300V rms.    Rate this link

    High speed telecom backplane connectors

    Today???s communication technology requires the transmission of higher and higher data rates. Currently, digital signal speeds on printed circuit boards (PCBs) range to about 2.5Gbps and are moving rapidly to 5Gbps. System designers anticipate employing signal speeds of up to 10Gbps in the next few years. This drives the need for enhanced hardware to cope with the signal integrity requirements of these systems.

    To cope with the amount of data being transmitted between boards, the connector needs higher pin counts as well as higher data rates per pin. These two factors tend to increase the crosstalk between connector pins. To cost effectively minimize this crosstalk the right connector has to be selected for the application early in the design process.

    In selecting a connector for an application the first criteria to consider is electrical performance. Once electrical performance is assured then mechanical robustness, assembly process and cost must be considered. The traditional connector electrical performance metric, crosstalk, is still the main performance criteria for lower speed designs. Impedance matching, bandwidth performance and crosstalk are the defining performance metrics.

    There are two broad classes of net topology used on backplanes, multi-point and point to point.

    In a multipoint topology, each driver is connected to many receivers and typically each receiver is located on a separate daughtercard. This is the traditional method of implementing data transfer across a bus and works well up to bus speed of 100-200 Mbps. For the multi-point net topology the driving issues for connector selection are density and crosstalk.

    Above 200Mbps the signal integrity aspects become increasingly unmanageable and point to point net topology is used. In point to point data routing, each driver is connected to one receiver and uses a more carefully controlled transmission path. The backplane connector largely determines the electrical performance of this carefully controlled transmission path. For point to point net topologies crosstalk is still a factor but the link performance or bandwidth of the transmission path becomes the primary concern

    The traditional FCI Metral 2-mm two-piece pin-and-socket connector has historically been the main connector of choice for backplane applications. As a result, a wide selection of sizes and styles are readily available. For example the CompactPCI system uses those 2-mm two-piece pin-and-socket connectors.

Computer connector

A typical modern computer system has many different connectors in them. There are many connectors like sockets, high density connectors, memory module connectors, card systems, USB, SCSI and many others,

The system board of a desktop computer contains connectors for power, expansion cards and disk drives. Expansion connectors are either ISA (Industry Standard Architecture) or PCI (Peripheral Components Interconnect). PCI has replaced ISA but both are normally supported. Additionally, various ancillary components such as speakers, cooling fans and status displays plug to the system board. In addition, I/O (Input / Output) connectors for keyboard, mouse, monitor, etc. are mounted to the board. The I/O connectors are typically a standardized configuration such as D-subminiature, USB, circular DIN, etc.

Circuit board connectors

For board-mounted connectors, termination configurations are traditional post-and-hole, surface mount, and press fit.

Typically, board construction determines the termination technique. For a board of standard thickness, the most common connector choice is the post-and-hole termination.

For a board of standard thickness, the most common connector choice is the post-and-hole termination. Thin, small boards and boards with a bottom heatsink tend toward surface mount, especially if other components are surface mounted. A thick, multilayer board will tend to use press fit connectors because soldering becomes more difficult for such boards.

Connector costs tend to rise as terminations move from post-and-hole to surface mount, to press fit. In general, post-and-hole connectors are the least expensive. The wave solder process for terminating these connectors is the most common and familiar.

Surface-mount connectors tend to have higher performance plastic housings, raising their cost slightly. They also tend to have lower power ratings. The surface-mount connectors simplify the soldering process and lend themselves to automated assembly techniques.

The press fit connectors require specialized compliant contact designs that increase costs again. Press fit connectors eliminate the need for soldering, they are just inserted to the circuit board at the right force.

In the case of wire-to-board connectors, the alternative terminations are crimp, solder, or insulation displacement.

    DIN 41617 Eurocard connectors

    31 pin DIN41617 connector was teken to use when 100x160 mm Eurocard circuit board size became popular. This connector has 31 round pins on two rows. Each pin is 1 mm diameter. The contacts are rated for 5A current.

    DIN 41612 Eurocard Connector

    DIN 41612 Eurocard Connectors are popular connectors used to connect Eurocard size circuit boards with many connection pins. The connectors are available in several sizes and pin confiigurations.

    The models with thin pins tightly packed pins (2.54 mm distance) are available in 64 pin (2 rows) and 96 pin (3 pin rows) versions. The pinc are rated for 1A current. The voltage rating is 125V. There is also a 32 pin version where only even numbered pins are used. In this 32 pin version the pin distance from each other is 5.08 mm and voltage rating of 250V according VDE0110.

    There are also industrial versions with 5.08 mm pin raster and 4 amprere per pin current rating. Industiral connectors are available in 32, 48 and 64 pin versions.

Telecom connectors

Telecom world has their own class of connectors designed for those applications in mind. Telecom connectors are generally designed the cable types used in telecom world epecially in mind. Telecom field uses lots of connectors for twisted pair cabling (for example normal telephone outlets), some coaxial cable connectors (mainly 75 ohms connectors) and a wide variety of fiber optics connectors.

Most commonly used connectors in telecom and datacom wiring are:

  • RJ-45: Short for Registered Jack-45, an eight-wire connector used commonly to connect computers onto a local-area networks (LAN), especially Ethernets. RJ-45 connectors look similar to the ubiquitous RJ-11 connectors used for connecting telephone equipment, but they are somewhat wider.
  • RJ-11: Short for Registered Jack-11, a four- or six-wire connector used primarily to connect telephone equipment in the United States.

Automation connectors

Automation world used lots of cabling and lots of connnectors.

    DIN rail connections

    Typically most small process autiomation system components like wire termination blocks are installed to DIN rails There are few variations of standardized rail types:

    • DIN 15 = EN 50 045 (15 mm wide)
    • DIN 35 = EN 50 022 (35 mm wide)

    The rail types are standardized in Europe and USA. DIN cased devices just snap the cases on to the rail. Please note that there are several variations of rail types. When selecting the rail type, check that the components you plan to instal can plug to that specific rail type. Many components connect only to one rail type, but the ones with "universal mount" mount nicely to more than one rail type.

    Circuit board terminal blocks

    Combicon (and other similar connectors) from Phoenix Contact have become very popular board termination block in use in industrial automation devices. The most commonly used connectors on this range are:

    • CLASSIC COMBICON: The CLASSIC COMBICON series is rated 10 amps/300 volts. The connectors can typically accept wires up to 2.5 mm2. Pin spacing available are 5.0 and 5.08 mm.
    • MINI COMBICON: The MINI COMBICON series is rated 8 amps/300 volts. The connectors can typically accept wires up to 1.5 mm2. Pin spacing is 3.81 mm or 3.5 mm.
    • MICRO-COMBICON: The NEW series of ultra-high density pluggable printed circuit board terminal blocks with a pin spacing of only 2.5 mm (.098") / 2.54 mm (0.1"). Available from 2-12 positions, MICRO-COMBICON has a current capacity of 4 amps at 125 volts. Plugs and headers are polarized and keyable to assure a proper connection. The plugs generally use a spring-cage termination and accepts a wire range of #28-20 AWG.
    • POWER-COMBICON: A high power connector that can accept wires up to 6 mm2 and current up to 40A. The pin spacing is 7.62 mm or 07.5 mm.
    • COMBICON with wider pin spacing: same as CLASSIC COMBINCON except pin spacing is 7.62 mm.

    Harsh industrial environment connectors

      Typical connector needs in very hard industrial environments:

      • Resistance to corrosion
      • Resistance to high pressure
      • Resistance to fire
      • Hermetic shielding
      • Underwater mateability

      Harsh industrial environments such as railways, petrochemical plants, nuclear facilities and offshore ??production platforms require a specialized approach and experience.

      • EN 175301-803 (ex DIN 43650): Connectors are mainly used for the electrical supply electrovalves as well as for small motors, pumps, level switches, photocells, etc.
      • Round connectors: Round connector with M12 and M8 threads are common in some automation applications.

    • European-Style Terminal Strips: Setscrews secure wires for reliable contact. Recessed-screw design helps prevent accidental contact with terminals.
    • Dual-Row Barrier Strips: Barriers between the positions help prevent accidental contact and short circuits. Popular in USA.

Audio/video connectors

There are many different connectors and wiring practices used in audio word. The most common connectors used are:

  • XLR: An XLR is a quite larger (about 5cm long, and 2.5 cm diameter) with (generally) 3 conductor pins (or recepticles) in a triangular pattern shrouded by the cover. As used on almost all pro audio equipment to carry balanced audio signals. XLRs are most typically used in microphone circuits, and PA system cabling. XLR connectors are commonly used in professional audio systems microphones and equipment interconnections. The audio signals are transported as electrical signal between pins 2 and 3. Pin 1 is used for shield ground. The origin of the XLR connector was the Cannon X Series connector. It was fitting the demands of the audio community except the missing latch. Cannon rearranged the pins and added a latch.
  • RCA: The RCA type is the regular consumer type used for unballanced audio. RCA is a lightweight small coaxial connector, with a centre pole that sticks out a little further that the shield flangy ring thing, and is quite small. The signal goes between a center conductor, and the shield or return side, which is usualy referenced to the case or outer sleeve section. The signal carried in this connector is usually consumer line level or sometimes low level signals from LP player. Practically all RCA connectors that are prone to noise problems, this is probably the number one source of bad connections. Typical consumer AV equipment (like VCRs), may have an audio source impedance of up to 5-20 Kohms, which cna cause problems with long cables (high frequency rolloff and easy pickup of noise). NOTE: RCA connector was originally intended for use at RF *inside* equipment and racks. Never was intended for audio with that long signal pin which mates before the shield!
  • 6.3 mm PHONO: This is a connector type original used for manual telephone patch panels. In audio world this connector is used for patch panels, equipment interconnections, some microphone connections and headphone connections. The stereo version of 6.3 mm (1/4 inch) PHONO plug is used to carry, depending on aplication, stereo headphone signals or balanced line level signals in equipment interconnections. Mono 6.3 mm PHONO plug is generally used to carry unbalanced line level audio signals in audio equipment interconnections. In some applications the same connector is also used for microphone level signals generated by microphones or instrument pickups (for example in electric guitars). In some applications 6.3 mm phono connector is used to carry speaker signals (not very recommended practice).The common ?? inch stereo phone plug was originally designed by the Bell Telephone Company around 1880, for use on telephone switch boards. That is why it is called a phone plug.
  • 3.5 mm PHONO: This is a miniature version of PHONO connector. 3.5 mm (1/8 inch) stereo PHONO plug/jack is commonly used in portable CD players, small radios and PC soundcards to carry stereo headphone signals or line level audio signals. In PC soundcards this connector is also used for mono electret microphone connections where that connector carries micrphone signal and microphone bias voltage.
  • 2.5 mm PHONO: This is a very tiny version of PHONO plug. It is used in some applications to connect microphones to wireless transmitters or video cameras. The most commonly used version is mono version, but also a stereo version of this connector. The wiring of the connector can vary from equipment to equipment but is on same general line as other PHONO connectors.
  • BATAM: This connector looks somewhat like a stereo PHONO jack which has a size between 6.3 mm and 3.5 mm PHONO jacks. This connector is used in some professional audio patch panel applications to carry balanced audio signals.
  • TT: This connector looks somewhat like a stereo PHONO jack which has a size between 6.3 mm and 3.5 mm PHONO jacks. This connector is used in some professional audio patch panel applications to carry balanced audio signals.
  • Banana plugs: 4mm banana plugs are very traditional speaker connectors. Banana plug is good connector for speaker signals, both mechanically and electrically. You can see those connectors on many audio amplifiers and speakers. Banana plug has it't problems. First you need two separate connectors to connect one speaker cable. Secondly the electrical safety is a problem, because exposed banana connector connected to powerful amplifier output can have dangerous voltages on it (speaker signal can be easily tens of volts in amplitude) and on some countried the banana plug is too similar to pins on mains power plug (especially in European countries). Those safety problems have caused compliance problems in European countries (CE marking). Nowadays there are also CE compliant innovative banana plugs that are approved worldwide as a loudspeaker connector, but the audio industry seems to be moving away from banana connectors (mostly to use Speakon connector for speaker connections).
  • Spade: High current spade lugs are sometimes used to terminate speaker cable. A spade lug can be easily connected to screw type terminals on speakers (those same terminals can also take bare wire).
  • SPEAKON: Neutrik NL4FC 4-Pole Speakon Connector is nowadays propably the most commonly used speaker connector type used in professional audio world. This is very reliable connector to terminate speaker signals. All Speakon Connector contacts on both connectors are touch proof, so the the connectors meet strict safety requirements. Speakons are designed for high-power use, they can handle 250V voltage and 20A continuous current, os they are more than adequate for even highest power audio systems. Speakon connectors are "non-shorting".
  • Other connectors: There must be 50 different random audio connectors on the market. They are designed for special market. Those special connectors are most often used with multi-pair cables (there is no single standard for those) and for some application where "standard" connectors are suitable (for example miniature connector versions in very small equipment).

The most commonly used connector in video wiring is BNC connector. Because the cable used it 75 ohms cable, the right connector type for this cable is 75 ohm BNC connector. The traditional usage of 50 Ohm BNC connectors on 75 Ohm cable with analog equipment (video & telco) has little distortion effect on the signal at frequencies below 300 MHz. However, digital signals in video and telephony applications have necessitated the usage of 75 Ohm connectors.

Video world uses also uses many other connector types:

  • F connector: For antenna connections
  • IEC antenna connector: For TV antenna connections
  • Firewire connector: Used on DV cameras
  • HD15: VGA display connections
  • Multipin connectors: control and camera cables
  • DIN: On old TVs for combined video/audio connections
  • SCART: 21-pin connector used in European consumer video equipment and TVs for audio and video interconnections
  • Triax connectors: Triaxial cables are used in TV broadcast industry for TV camera interconnections (connecting camera to CCU and supplying power to camera). There are several different triax connector types in use in TV industry.

Test equipment connectors

Banana connectors

4mm banana plugs are very traditional connector that are used to do connections on electronics laboratories. This kind of connectors are found on most multimeters and laboratory power supplies. Banana plug is good connector for this kind of applications, both mechanically and electrically.

With banana plugs the electrical safety can a problem, because exposed banana connector connected to high voltage source can have dangerous voltages on it. On some countried the banana plug is too similar to pins on mains power plug (especially in European countries). Those safety problems have cause potential safaty problems with use of banana plugs in electronics laboratories.

While the accidentally plugging the banana plug to main outlet is not such a problem in laboratory as it could be in home, there are still real dangers. When the wires with banaa plugs are used to carry dangerous voltages, a loose or free banana plug end can expose dangerous voltages (for example when wire gets pulled out from multimeter terminal). For those dafety reasons it is nowadays recommended that normal banana plugs are not used for higher voltage than several tens of volts in laboratory system.

In case of higher voltages are handled, safer connectors should be used. Safety shroud banana connectors are the connectors suitable for higher voltages operation safely (voltages up to 1000 volts). Safety shroud banana plugs are just banana plugs are covered for extra protection. The voltage on them cannot be touched with finger even when they are not connected to the device. Safety shroud banana plugs can ganerally be plugged to banana jacks that are designed to take shrouded banana plugs. Most modern multimeters have this kind of jacks so they can accept cables with both normal and safety shrouded banana plugs.

In addition to 4 mm banana plugs, some test systems use 2 mm banana plugs. Please note that there are two variations of 2 mm banana plugs in use: one uses spring on plug (like 4 mm banana plugs) and other type has jacks with springs.

RF connectors

RF coax(ial) connectors are a vital link in the system which uses coaxial cables and high frequency signals. Coax connectors are often used to interface two units such as the antenna to a transmission line, a receiver or a transmitter. The proper choice of a coax connector will facilitate this interface.

Coax connectors come in many impedances, sizes, shapes and finishings. There are also female and male versions of each. As a consequence, there are thousands of models and variations, each with its advantages and disadvantages. Coax connectors are usually referred to by series designations. Fortunately there are only about a dozen or so groupings or series designations. Each has its own important characteristics, The most popular RF coax connector series not in any particular order are UHF, N, BNC, TNC , SMA, 7-16 DIN and F. Here is quicl introduction to those connector types:

  • "UHF" connector: The "UHF" connector is the old industry standby for frequencies above 50 MHz (during World War II, 100 MHz was considered UHF). The UHF connector is primarily an inexpensive all purpose screw on type that is not truly 50 Ohms. Therefore, it's primarily used below 300 MHz. Power handling of this connector is 500 Watts through 300 MHz. The frequency range is 0-300 MHz.
  • "N" connectors: "N" connectors were developed at Bell Labs soon after World War II so it is one of the oldest high performance coax connectors. It has good VSWR and low loss through 11 GHz. Power handling of this connector is 300 Watts through 1 GHz. The frequency range is 0-11 GHz.
  • "BNC" connctor: "BNC" connectors have a bayonet-lock interface which is suitable for uses where where numerous quick connect/disconnect insertions are required. BNC connector are for exampel used in various laboratory instruments and radio equipment. BNC connector has much lower cutoff frequency and higher loss than the N connector. BNC connectors are commonly available at 50 ohms and 75 ohms versions. Power handling of this connector is 80 Watts at 1 GHz. The frequency range is 0-4 GHz.
  • "TNC" connectors are an improved version of the BNC with a threaded interface. Power handling of this connector is 100 Watts at 1 GHz. The frequency range is 0-11 GHz.
  • "SMA" connector: "SMA" or miniature connectors became available in the mid 1960's. They are primarily designed for semi-rigid small diameter (0.141" OD and less) metal jacketed cable. Power handling of this connector is 100 Watts at 1 GHz. The frequency range is 0-18 GHz.
  • "7-16 DIN" connector: "7-16 DIN" connectors are recently developed in Europe. The part number represents the size in metric millimeters and DIN specifications. This quite expensive connector series was primarily designed for high power applications where many devices are co-located (like cellular poles). Power handling of this connector is 2500 Watts at 1 GHz. The frequency range is 0-7.5 GHz.
  • "F" connector: "F" connectors were primarily designed for very low cost high volume 75 Ohm applications much as TV and CATV. In this connector the center wire of the coax becomes the center conductor.
  • "IEC antenna connector": This is a very low-cost high volume 75 ohm connector used for TV and radio antenna connections around Europe.
There are also some special connectors and special variations of connectors used for some special applications. For example FCC has required that suppliers of RF LANs (local area networks) have an RF interface that cannot be matched by the present available RF connector series (idea is to prevent connecting higher gain antennas to those devices). As a result, several so called "reverse polarity connectors" have been designed. The reverse polarity TNC is one of the most popular where the threads are left-hand instead of the conventional right-hand type.

Maybe the most commonly seen RF connector is the BNC connector. Designed originally as a tightly specified co-axial connector for low power RF applications,the BNC has become the connector of preference for many communications,video and,until recently,computer network installations.Its use over the years for increasingly varied applications has seen numerous variants,in terms of adapting to various cable types and sizes,of assembly (mainly compression gland or crimp styles)and,maybe most controversially,of characteristic impedance.

Car connectors

Connectors are critical to today's cars. Without them, it would be nearly impossible to build or service a car. Whenever a bundle of wires passes through or attaches to a component of the car that might have to be removed, there must be a connector there to allow for that removal.

Modern cards have lots of connector in them. Car environment has some special demands on connector and are used in large numbers. Many car manufacturers use connectors that are pretty much custom designed for them or customized for their uses.

In the past, unreliable connectors have been the source of many electrical problems. Connectors have to be waterproof (modern connectors have several seals to keep out moisture), corrosion proof and provide good electrical contact for the life of the vehicle.

Typical features of car connectors:

  • Quick coupling and uncoupling (for fast repairs and card building)
  • High shock and vibration resistance
  • Can withstand contamination
  • Waterproof connection needed on some special places

Transportation industry employs a quick-release coupling mechanism connectors for various applications.

Solderless crimp connectors provide a poor protection against corrosion and require a special crimp tool. Crimp and seal splice sleeves should be used in car installations. The isulation of the Crimp and Seal splice sleeve is made of shrink tubing that will shink to the wire, and epoxy inside the tube will melt and glue itself to the insulation material. Crimp and seal splice sleeve provides a superior protection against the elements and provides a water proof repair.

Power connectors

Power connectors are designed to carry lots of power. Special considerations are used in power connectors for the to carry high currents (and sometimes high voltages also) nicely. The general purpose data connectors have asually limited use in power applications, because they have limited power handling capacity per pin, which usually leads to use of parallel contacts to spread the power load. In such cases, the number of positions must be on the high side to improve reliability. Another problem with using signal connectors for power applications is that the catalogs rarely offer derating tables and data regarding power performance.

Choosing the right power connector for your application may be one of the most important interconnection choices to make in a product's design. The appropriate connector can provide a reliable means to modularize, downsize, or improve manufacturability and field maintenance.

There are several criteria to consider in selecting the power interconnection system. These include:

  • Current rating (current density)
  • Connector size (circuit density)
  • Engagement force (force or effort required (stated in pounds/ circuit) to connect, mate, or engage the two populated connector halves)
  • Wire size;
  • Configuration and circuit size
  • Operating voltage
  • Agency approvals (listings)
  • Price per circuit
Each of these criteria must be considered in selecting the best power interconnection system. The most important of these criteria, however, is current rating.

Current rating or current density is the most important criterion in the selection of a power interconnection system. It is stated in amperes per circuit and is a measure of the amount of current that can be passed through a mated terminal that will give no more than a 30 degrees C (85 F) temperature rise over ambient 22 degrees C (72 F). This current level is then derated or adjusted for the number of circuits in a given housing (2 to 15 circuits per housing typically) due to the heat (temperature rise) of the adjacent terminals. For example, a typical power connector can carry up to 12 amperes/ circuit on a 2- or 3-circuit housing, but only 7.5 amperes/ circuit on a 12- or 15-circuit housing.

Published current ratings in catalogs are often for a single contact pair isolated in ambient air. This is an ideal and artificial situation. The presence of a housing around a contact pair will inhibit the convective and radiation cooling mechanisms to such an extent that conduction cooling predominates. For this reason often the size of the wire terminated to the contact significantly affects current carrying capacity. Larger wires allow a higher current for the same temperature rise. The contact aging an number of mating cycles a contact mated pair undergoes also affects its power rating over time

. If the connector is to be mated or unmated while the circuits are live, other power considerations come into play. For example, the application may require a connector with ground pins. Thus, the designer should consider connectors that incorporate a set of longer pins designated as ground pins. This means that during mating and unmating, the ground contacts will make first and break last within the connector, aiding the electrical stability of the circuit. In mains connectors this is usually a safety requirement for the mains connector.

The availability of strain reliefs or backshells for the power connector can be a major criteria in the extra degree of safety that the non-conductive strain relief housing provides. Should a terminal or wire become dislodged from its seated position in the connector housing due to being mechanically over-stressed (that's a technical term for "pulling on the wire too hard"), the strain relief can prevent the "live" wire from contacting other components or "neutral" conductive members.

The housing and terminal materials and terminated platings chosen are the last major decisions to be made. Most power connectors are made from a nylon plastic. The standard terminal plating options available for most power connectors are tin, tin/lead and overall or select gold. Tin or tin/lead platings are appropriate for most applications where per circuit currents are above 0.5 A. Gold plating should generally be specified in signal or low current applications where high mating cycles (more than 30 cycles) are likely or within harsh environments. Terminal base materials are either brass or phosphor bronze.

The price of the connector system should be calculated on the basis of total applied cost, i.e., the cost of the housing (both plug and receptacle), the cost of the terminals, plus the cost of the labor to attach the wire to the terminal and to insert the terminal into the housing.

    Mains power connectors

    Different countries and different environments use differnt mains connectors. In USA NEMA Plug & Receptacle configuarations are common. In Europe the normal single phase domestical power plugs are mainly at least somewhat country specific, and for higher current & three phase power CeeForm (CEE 17 / IEC 309) connectors are used.

    Most commonly used mains connector models:

    • The CEE 7/7 ("Schuko") grounded plug is used as a standard in Germany, Austria, Norway, Sweden, Finland, the Netherlands, Belgium and France; it is also used in Portugal and Spain. "Schuko" is rated for 10-16A 250V. variation of the CEE 7/4 plug with 4mm contacts is used in Eastern European countries and in some Soviet republics. Variations of the CEE 7 plug are also used in Northern Africa, the Middle East and Brazil.
    • Many small electronics appliances in Europe use small flat "Europlug" connector. The Europlug originated as CEE 7 and has been around for almost 30 years. It is a clever design that fits all the historic national sockets in all European countries, except for the UK. IEC 884 is one spec for the "Europlug" (BS EN 50075). Europlug is used in small electrical and electronic devices that need no protective ground and consume less than 2.5 A.
    • CeeForm (CEE 17 / IEC 309) is the European standard for highish-current connectors, available in 16, 32, 63 and 125A single and three-phase varients. The CeeForm connectors are widely used in Europe for connection of three phase power. Ceeform is water protected, so it will happily sit in the rain without tripping the mains out. Ceeforms are available in splashproof (IP44) and watertight (IP67) versions. The size of the device is determined by the amperage rating. It is virtually impossible to couple a plug and receptacle of different voltage and/or amperage ratings. CeeForm plug are available for maximum operating voltage of 600V RMS. CeeForm plugs are widely used in industrial applications.
    • In USA NEMA Configurations for general-purpose nonlocking Plugs and Receptacles are generally used. Those configuarations and plugs are available for single phase, twoo phase and three phase power applications. The most commonly used being 15A plig wiring for single phase power (125V). The most common NEMA configurations are US Nema1-15P (2 pins non-grounded) and US Nema5-15P (3 pins grounded).

    There are also many other connector types in use in different countries and special applications.

    Some most commonly used mains connectors used in equipment end are based on IEC 320 standard. A system to power accessories (such as monitors, disk drives, printers etc.) almost anywhere in the world can be designed by the use of an accessory power system based on the international IEC 320 connector pattern. The most commonly used IEC 320 connectors are the following:

    • The connector which is by far the most standard throughout the world is defined in IEC publication 320, standard sheets C13-14. IEC 320 standard C13-14 (also sometimes referred as sheet E) connector is a three pin gounded connector used for attaching the power cord to the equipment (you will see this kind of connector in the back of a typical desktop PC power supply). IEC 320 plugs may be earthed or not. An earthed IEC 320 plug will mate with a non-grounded male receptacle. In contrast, a non-earthed (2 pin) IEC 320 plug will not mate with an earthed version (3 pin) due to the pin configuration. The devices which use IEC 320 are limited to take 10 amperes or less mains current. . The 10 amperes corresponds to the current rating of the connector itself and to two current carrying conductors of an the minimum size flexible cord that can be generally purchased to mate with the IEC 320 connector. IEC 320 plug is not used as power connector in the wall. It is only used in equipment and some special extension cords. It is possible when using cord sets that incorporate this connector to connect power to a product with any of nine different cord sets so that the product can be easily modified to operate anywhere in the world.
    • IEC publication 320 standard sheets C15-16, is also used fairly frequently. This three pin connector is intended for service in higher temperature applications with service to 120 C and a current rating of 10 amps. This connector system incorporates a keyway which prevents entry of cable terminated connectors described in IEC 320 standard sheets C13-14. The C15-16 connector is generally specified as a rewireable device.
    • IEC 320 standard sheets 19 & 20 describe a connector rated at 16A/250 (20A in North America) It is rated at 65oC and permits detachable power connections for higher power products.
    • IEC320 C6 connector is a miniature version of IEC 320 E type connecvtor. The maximum current handling capacity of this connector is 2.5 amperes. You can see this kind of connector in many modern laptop computer power supplies.
    • IEC320 C8 is a two pin small connector used in many small equipment (for example many radios). The current carrying capacity of this connector is 2 ampreres.
    Other equipment power connectors:
    • PowerCon is a latching power connector, used to supply mains power (single phase) to equipment. It is similar to Neutrik's Speakon connector series (but does not mate to them for safety reasons). This kind of connectors are likely to be found only on equipment destined exclusively for the professional market (some countries prohibit use of them in domestic equipment). For example some professional power amplifiers and active speakers use this mains connector.
    • CeeForm connectors (male), both single phase and three phase, are also used in some very high power equipments as power inlets.

    Here are some links on mains connector information:

Military connectors

The connector of U.S military standard MIL-C-5015 (MS connectors) has been developed for the electrical and electronic connections of the aero equipment, but recently it is applied to the industry and used in general areas with high quality , various grade and reasonable cost. Those same connectors are also used in communication equipment, transport vehicle, ship, railroad, aeroplane related equipment, industry and machinery devices, measurement and medical equipment, computer etc.

MS connectors need no tools for coupling and assembling of the connectors when attaching cables to equipment. It is simple to couple the connector by inserting the coupling nut of barrel into the receptacle and turning to the screw direction.

MS-connectors are available in various version with pin number from 1 to 100 per connector. There are different version with differenct current ratings from 13A nominal current to 150A nominal current. The voltage rating is 200V to 1750V depending on connector version. Contact arrangements are specified in MIL-STD-1651A.

The MIL-C-26482 Series I connector is widely used for the military communication system since it is small sized and the electrical, mechanical, and environment properties are excellent. Communication equipment, transport vehicles, medical and measurement instruments, industrial machines, electrical and electronic devise.

Underwater connectors

Making connectors

There is a lot of connectors in the world, so it is very rate when you need to make your own connectors. But in some rare occasions you need to do that. For example if you need to use ageing equipment with obsolete connectors that are not available anymore, the techniques for making your own connectors may come handy.

    How to make non standard connectors with pins

    One way of making non standard connectors with odd format is the following:

    • 1. Find a connector with pins that will fit into the socket your trying to mate to. You can try pins taken from different commercial connectors.
    • 2. Solder wires to your pins
    • 3. Put bit of cling film or polythene over target socket
    • 4. Push soldered pins into socket through film
    • 5. Cover pins and wires with epoxy putty and leave to set.
    This has produced you a solid homemade connector. This method can be used for example to make odd format DIN plugs by using normal DIN plug pins as the pins.

    In some cases where you do not need a solid proof mechanical strangth (for example on some quick experimenting in laboratory) you can also consider using the method above but use a hot glue instead of epoxy.

Connector measuring

  • Measuring connectors - would like to replace one connector type with a different, less expensive model. How do I prove the two connectors have the same electrical characteristics? Also, how will the power and ground-pin assignments within the connector affect its performance?    Rate this link

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