Cable lugs: purpose, types of connectors for crimping and features of cable crimping

Crimping the ends of wires with bare cores that are connected to electrical equipment and devices is a reliable way to connect contacts and ensure a stable current. The crimping process cannot be imagined without the use of special equipment (hand presses, machines) and cable lugs in the form of sleeves or flat, round, hook, fork terminals. All of them differ in shape, size, type of crimping, and purpose.

Purpose of cable end terminals

Every resident of multi-storey buildings at least once had to deal with the problem of incorrect cable connection in the distribution board, which is installed on a block of apartments. This leads to melting of the wires and the appearance of twists.

Cable lugs can prevent such problems, protect residents from overheating and ignition of the wiring caused by poor-quality contact or lack of special terminals.

Crimping the wires with end caps ensures high-quality contact in the connections and stable contact resistance, which minimizes the risk of fire when the current load increases.

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Types of crimping tips

For crimping cables, special conductive elements are used - sleeves and lugs for wires for crimping. Depending on the type, they can be installed on electrical cords with one or more conductors of different cross-sections. A special role in the choice of plugs is played by the purpose of the wire and the material. For copper or aluminum conductors, the corresponding lugs are used.

Among a wide range of conductive elements the following types of products are common:

1. Tinned copper tube lugs, one side of which looks like a flat piece of metal. The reverse side of the terminal is represented by a small hole, which serves as a place for attaching the connecting plug by means of a screw. In addition, there are models without a protective tin coating obtained by tinning. Similar products are marked as ТМ-Х-У or ТМЛ-Х-У.
2. Lugs for crimped wires with a control window, serving as an end element for connecting the cores of cables of various cross-sections. The peculiarity of such products is that the crimper is able to control the process through a special hole. The marking of this type of end caps looks like MTL (o). Installation of tips with a control window can be carried out with clamps, soldering or soldering, which allows you to reduce the value of the contact resistance to a minimum.
3. Aluminum-copper lugs designed to connect wires with copper and aluminum conductors to each other (they are a type of products with a window).
4. Cable lugs of the NShP type (pin), distinguished by their miniature dimensions. Such elements are often used in electrical equipment and automatic circuit breakers of protective devices.
5. Pin bushings with and without insulation (NSHVI) made of electrolytic copper. Such products are used in everyday life and industry for crimping wires with a cross section of up to 35 mm. Crimping is performed using special crocodile clips.

The main types of tips are subdivided into tinned, end, pin, insulated, fork, hook. In shape, they can be circular, flat, round, cylindrical, etc.

Crimp sleeves

Crimp sleeves are another type of end connector. These products are often used to change the parameters of the electrical network in various devices and appliances. Devices are selected according to the type of connecting wires (copper or aluminum conductors).

Products for cables with copper are designated as GML, where:

• G - the name of the conductive element (sleeve);
• M - material from which the end cap is made;
• L - an indication of the presence of a protective coating (tinning).

Connectors for wires with aluminum conductors are designated as GAO (closed sleeve). If it is necessary to connect cables with the transition of copper to aluminum, then you should opt for a combined alloy product.

Crimping tool

In special productions, electricians perform crimping of wires using special machines, which are equipped with dies for crimping certain connectors. For home use, hand pliers and clamps are more suitable.

The principle of their operation resembles a machine press, but all work is done manually. To do this, it is enough to put the lug for the cable in a special hole in the tool, direct the wire strands into the connector and apply maximum effort when pressing the handle.

The choice of special equipment directly depends on the cable section. Most often the following tools are used:

1. Presses in the form of pincers, type PK2 and PK2M for manual crimping of ferrules. Such devices are used for crimping multicore cables with a cross-section of up to 10 mm².
2. Clamps-pincers of the PK1 and PK1M brands, differing from the previous models by a reinforced tool with extended handles for terminating wires with a cross-section of up to 50 mm².
3. Hydraulic hand crocodiles for effortless crimping of conductors up to 10 mm².
4. Industrial crimping tools for large wire cross-sections (up to 240 mm²).
5. Presses with hydraulics, electric drive or foot pedal for crimping cables up to 300 mm².

For convenience, manual hydraulic pliers can be installed and fixed at the corner or edge of the table, then the crimping process will be simplified, because you do not need to squeeze both handles of the tool. It is enough to push the top handle with full force. However, if you overdo it with the force of pressing, the crimping device may fail.

Wire preparation and termination process

Before proceeding with the crimping of the cores with a tip, you should prepare and strip the wire from insulation. The preparatory steps are quite simple: to do this, you need to manually clean the required length at the end of the cable (pliers) or using a special stripper, which visually resembles a pistol with small holes. After that, the fluffed veins must be smoothed and slightly tightened, this will avoid cutting them during the crimping process.

The next step is to insert the wire into the cable lug from the “skirt” side. It is important that the connector matches the wire size (it should not fit too tightly or loosely). After that, you can start crimping. If the clamp is fixed on the table, then the end cap is installed in the desired slot of the matrix, after which the conductors are inserted and crimped.

If this is the first time the termination is carried out, then you should first practice on short lengths of cables. To make the connection reliable, strong and of high quality, you must adhere to simple crimping rules:

1. A cable inserted into a lug or sleeve must be held in the socket by hand.
2. Before crimping, it is recommended to make sure that the matrix is ​​selected correctly.
3. It is necessary to squeeze the handle of the press until a characteristic click, emitted by the ratchet mechanism, appears.
4. In case of unsuccessful crimping, the clamp handle is blocked, the mechanism must be unclenched manually.
5. When using a dual-loop crocodile, it is recommended to make sure that no insulation is trapped in the slot for the metal tip.

Never use pliers, chisels, hammers, or any other non-specialized tool to crimp wires and cables. Such an impromptu crimping will not be able to provide high-quality contact at the joints and stable contact resistance.

Modern technology and electrical appliances, a well-equipped shield cannot be imagined without cable lugs. Their smooth operation and high-quality contact directly depends on the correct selection of tools, connectors, wires with the desired section. Careful attention to such details will help to avoid overheating, short circuit and fire.