Power connectors
(1 988)Power connectors available from TME have been divided into these categories:
- AC connectors,
- DC connectors,
- solar connectors,
- terminal blocks,
- LED connectors,
- rail-mounted connectors.
AC power connectors
The possibility of connecting electronic devices to electrical networks in buildings is provided by AC sockets and plugs. Usually, the difference between them is the voltage and current value, shape, size, and connector type – there are about 20 types of sockets and plugs in common use around the world.
If we travel often, we can get a so-called multi-type socket, which is an adapter that will match different types of sockets and will allow us to plug in a device bought in another country. We should remember that adapters must be of good quality, because incompatible ones may be dangerous and fail to provide an adequate performance for the given network.
A plug is a moveable connector attached to an electrically powered device, while a socket is attached to a live electrical circuit, usually located in a building. Plugs are most often male connectors (with pins) that match contacts (holes) in the female socket. Sometimes, sockets also have a fuse providing additional protection against incidents that may threaten users or rooms in a given network.
Sockets have safeguards, too. The single-phase ones have two connections to the power circuit, but also a third contact used for connection with the ground. Sockets can also be equipped with a protective cover, but as they are an element of interior design, their outer casing usually ensures proper protection anyway. They are usually made of plastic.
Protection against accidental contact
Sockets and plugs are usually designed to prevent fingers from contacting live parts. This reduces the risk of fire and electric shock. Pins are generally covered with insulation along part of their length, which ensures higher safety while putting in and taking out the socket. There may also be shutters to stop foreign bodies from getting into the socket. Some types of sockets are equipped with switches and fuses.
Ground connection
Currently, nearly every socket has a third contact used for ground connection. Ground connection secures the insulation of the connected device from damage. Plugs are generally designed in such a way as to have the ground contact connected before connecting the live circuit contacts.
All devices are IEC certified, for classes which require compliance with the guidelines related to grounding. Class I are devices requiring grounding in the socket and plug, while Class II elements protect the user with a double insulation, where grounding is not required.
DC plug, i.e., DC power connector
To simplify the process of choosing DC power connectors, we need to have a look at the types of these devices, key specifications, and widely accepted nomenclature. It is also worth having a look at audio and USB connectors in power applications.
A proper choice of a DC power connector is often overlooked in the engineer’s final design. Even though these are relatively easy and uncomplicated components, DC power connectors still require basic knowledge to ensure that we have made the right choice.
The role of DC power connectors
Also known as barrel connectors, DC power connectors will have current and voltage ratings specified by the manufacturer to ensure reliability in power applications. The socket and plug of a standard DC power connector usually has 2 wires. One wire is exposed, and the other one is recessed to prevent an accidental short-circuit between them. As barrel connectors are nearly always used to power an end application, there is practically no risk of damaging other components by plugging a DC connector to an incorrect port.
DC plug a – dimensions
When choosing a barrel connector, we need to decide carefully on the inner pin and outer sleeve diameters.
Although play between the components of a DC plug has not been normalised yet, the inner sleeve diameter (which touches the inner pin) should be slightly bigger than the diameter of the mating pin. However, in the outer sleeve and its corresponding connector, the play is not critical for the correct functioning of the connector, because the connection with the outer sleeve is made using a flat metal plate spring.
Except for the inner diameters of the contacts and the outer sleeve, the depth to which it is to be inserted is another important specification of the DC power plug to which we should pay attention. In this case, too, there are many parameters that we should take into account when choosing the size.
DC power connector cables
A standard DC power socket or plug has two wires with a center pin (usually for powering) and an outer sleeve (usually for grounding). However, reversing this configuration is acceptable. The third wire, which makes up a switch together with the external sleeve conduit, is also available in certain models of power sockets. The switch may be used to detect or indicate the plug insertion or to choose between power sources, depending on when the plug is or is not inserted.
Mounting options
Like in the case of many other components, there are a few options for mounting the DC power socket depending on its final application.
The panel-mounted DC power socket ensures convenient installation in any place on the product casing, with no need to connect cables to the electronic circuits. In the case of PCB-mounted DC power sockets, SMT mounting is most common with a through-hole, both horizontally and vertically.
A range of DC power sockets with SMT signal connections will also offer pins or hooks with through-holes to further secure the socket on the printed circuit board. They could be connected electrically, but they will be through-soldered to the printed circuit board.
Audio connectors used to supply power
Even with the possibility to send electricity and voltage, standard audio connectors are not recommended for powering electronic applications. This is because not all manufacturers determine voltage and current parameters for audio connectors. Secondly, if an audio plug was connected to the power supply, its exposed wires could easily cause an accidental short-circuit between two or more wires. Finally, if the audio plug supplied energy, it would be easy to connect it to other audio sockets, which are not designed to receive power, and lead to damage of inner elements.
USB power plugs
Unlike audio connectors, USB connectors are widely known for their capacity to supply power and send data. However, their maximum rated powers were significantly limited until the USB C standard was invented.
A USB C connector with four power contacts and four grounding contacts has a rated current of up to 5A, maximum rated voltage of 20V and rated power up to 100W. This ability to supply energy made it an attractive solution for powering. However, in applications in which its only function is charging or powering, fast data transfer can create unnecessary costs. As a result, USB C connectors without pins to transfer data have become a more cost-effective option for projects which need only power supply.
Solar connectors
In any photovoltaic installation, the type of a solar connector used in the module is important. Pre-attached cables for solar modules, with their size, type of insulation and length, are generally mentioned in each technical specification. The diameter of a cable is usually 4mm², its length is 1200mm and the material from which it is made is copper with XLPE insulation. IP67/68 rated MC4 lockable sockets are connected to the cables, MC4 being the actual current standard for such sockets.
Terminal blocks
Terminal connectors, also known as connection terminals or terminal blocks, are modular blocks with an insulated frame which secures two or more wires together. It consists of a clamping element and a conductive tape. The insulated terminal block strip body contains an element which conducts current (a metal strip or a terminal strip). It is also the basis to mount the element. The body is equipped with a mounting system, thanks to which we can easily mount or unmount the blocks on a printed circuit board or a mounting rail. Most terminal strips are modular and intended for mounting on a DIN rail. This creates the possibility to extend the terminals as required. Thanks to terminal blocks, a much safer connection is ensured, and the wires are organized in a better way.
LED connectors
One of the reasons why strip lighting has become popular is because we can connect them, create eye-catching highlights, and get the effect which convectional lighting cannot offer. We can do this in two ways. The first one is by soldering. However, this method requires adequate tools and skills.
The easier and more convenient alternative is using connectors. These small but useful accessories can revive every space using a simple clip. When creating your own LED strip using connectors, we need to remember to have the power supply big enough to handle all the connected strips. Additionally, depending on the number of connected strips, you may also need amplifiers to obtain constant brightness.
Rail connectors
A DIN rail is a standard metal rail, widely used for mounting circuit breakers and industrial controlling devices in cabinets. These products are usually made from cold-rolled carbon steel sheet, with a light-coloured galvanised or chrome-plated surface. Even though they are metal, they are intended only for mechanical support and not used as a busbar for electric current conduction, but they can ensure a ground connection of the device casing.
The task of rail connectors is to connect wires and cables in control cabinets in such a way that they are arranged in a clear and ordered way, which can be achieved mostly by using connectors in different colours. The connectors are adapted for DIN-rail mounting.
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