Terminals for wires are an integral part of any electrical network. After all, it is poor contact that is the main cause of breakdowns and malfunctioning of any electrical devices.
And some electricians even joke that electrical engineering is the science of contacts. Therefore, the high-quality connection of wires and cables should be given the utmost attention.
Terminal strip types
At the moment, terminal blocks can be rather conditionally divided into several main types. First of all, these are special lugs for wires, which ensure the subsequent possibility of commutation. In addition, there are terminals by themselves that provide contact between multiple conductors.
Lugs for wires
First of all, let's look at a variety of wire lugs. Usually they have a crimp type of fastening, but there are models equipped with screw terminals. The range of their application is truly huge. They are used both in low-current networks and for switching power cables, for which they are mandatory.
So:
- First of all, let's look at the terminals for the knife wire. They are widely used in the automotive industry and in general in low-voltage networks. The design of these terminals assumes the presence of two types of fastening - dad and mom. Some tips look like a knife, which is where the name comes from, and the second terminals have a design that ensures reliable fastening of this "knife".
- Blade terminals can be made straight and rotatable, which significantly expands their scope and simplifies installation. To isolate the connections, special insulating covers are used. If there is no sense in the insulation of the direct contact connection, then it is possible to use terminals with insulation of the crimping point.
- Typically, these terminals are available with the ability to crimp wires up to 2.5 mm 2. Although you can find models with the ability to use wires with a cross section of up to 6 mm 2.
- Fork-type terminals are designed for switching power and secondary circuits. These lugs are designed for subsequent screw attachment directly to equipment or to rails. The instruction advises to use them as a temporary contact or a contact requiring frequent reconnection.
- The design of the fork lugs is a two-pronged fork, which is where the name comes from. This design allows for a fairly simple switching without completely unscrewing the screw clamp. At the same time, in the connected state, it provides a sufficiently tight contact.
- Fork lugs are available for wires with a cross section of up to 6 mm 2. The wires are attached to the terminals by crimping. This location may or may not have an insulating cover in various variations.
- More reliable contact is provided by the so-called ring terminals. Like their forked cousins, they are designed to be fastened with a screw clamp. But thanks to the round shape of the contact part, they provide a large contact area and reduce the risk of tips "jumping out".
- Ring terminals for wires are such a good solution that they are used not only in low-current networks, but are also a mandatory attribute of power cables of any cross-section. In this case, the method of attaching a wire or cable to this type of lugs can vary from welding and soldering to crimping.
- Ring terminals are available in copper, aluminum, brass and copper-aluminum. Their cross-section can vary greatly, ranging from small terminals for a C-grade screw and ending with bolts of 27 or more. However, terminals for low-current networks can be supplied with crimp insulation.
Note! In addition to the above, there are other types of terminals. So you can find terminals for acoustic wires, a variety of needle, plug and connection terminals. They are not often found and for the most part use a crimp type of attachment to the wire.
Clamping terminals
To connect power grids with a rated current of up to 25A, sometimes up to 50A, screw and clamp terminals are used. This type of connection does not require additional lugs for the wires and allows you to simply mount a high-quality connection.
So:
- First of all, consider the clamping terminals for screw-type wires. Usually they are made of dielectric (plastic, carbolite, etc.) inside which there are brass terminals with screw terminals.
- The advantages of such terminals include high-quality contact, ease of installation and a wide range of wire cross-sections with which such terminal blocks can be used.
- Disadvantages include poor combination with aluminum wires and stranded copper wires. The fact is that when clamped, the screw can either completely transfer the soft aluminum wire, or significantly reduce its cross section. The same thing happens with stranded copper wire.
- A partial way out of this situation may be the additional use of needle tips or brass tubes, due to which the price of such an installation increases slightly, as does its time. A wire is first inserted into such tubes, and only then clamped with a screw. Due to this, the rotational movement of the screw does not cause significant damage to the conductor.
- The so-called quick-release terminals are even easier to install. The body of such a terminal block is made of a dielectric, inside which there is a spring. When the wire is inserted into the terminal block, this spring ensures proper pressure on the wire and reliable contact.
- The advantages of such terminals include ease of installation and reliability of clamping aluminum and copper wires. Possibility to use needle lugs for mounting stranded wires.
- But there are many disadvantages of such terminals. First of all, this is the impossibility of using stranded wires, in addition, under the influence of temperature changes, the reliability of the clamp decreases sharply as a result of the weakening of the spring.
Note! If the terminal for the wires is to crimp exactly the multicore cable, then special spring terminals are used. They have a special lock that allows the wire to get into the attachment point. After installing the wire, the lock is closed and the spring clamps the wire. These terminal blocks are almost ideal for stranded wires.
- Connection terminals can become a separate topic for discussion. Mostly they have crimp connections, but it is also possible to connect by soldering. Such terminals are used mainly in cases where there is no supply of wire for connection with conventional terminals.
- Such terminals are often referred to as connecting sleeves. They are usually made of brass tube. Sometimes it has an additional insulating coating.
- Thanks to this design, you can insert the wire from both ends of the sleeve and use the crimp method to connect it yourself. In this case, the proper level of contact will be ensured, and you do not have to resort to soldering the wire.
Output
Not all types of terminals currently on the market have been included in our brief overview. Indeed, now there are a huge variety of them for a wide variety of compounds.
Many of them are intended only for certain types of connections or wires, so it is simply impossible to describe them all. To facilitate the issue of choosing terminals specifically for your tasks, you can watch the video on the pages of our website.