RU191168U1 - Electric cable for control and monitoring circuits - Google Patents

Abstract

The utility model relates to conductive equipment. The cable contains a core 3, on the outside of which a belt insulation 4, a screen 5 and a sheath 6 of thermoplastic material are sequentially arranged. The core 3 is made in the form of a four-pair beam. The bunch is formed by twisted in pairs and equipped with insulation 2 conductive cores 1. Technical result: increased reliability.

Description

The technical field to which the utility model relates.

The utility model relates to electrical engineering, in particular to the design of electric cables mainly for control circuits, control and data transmission in industrial, transport and energy facilities, in particular, in nuclear power facilities.

State of the art

A large number of electrical cable designs are known in the art.

As the closest analogue, a known electric cable containing a core is selected, the outer core of which is sequentially insulated, the screen and the sheath are made of thermoplastic material, said core is made in the form of twisted bundles, each of which is formed into twisted pairs twisted and insulated with conductive conductors (RU 83875, published on 02/03/2009). The disadvantage of this known cable is the lack of stability of the functional and mechanical parameters in conditions of high seismic activity.

Utility Model Disclosure

The technical problem solved by this utility model is to create a low-current electric cable with high operational reliability in conditions of intense dynamic loads.

The technical result achieved is to improve the operability of the cable by increasing the stability of electromechanical parameters, in particular transient attenuation, and fire safety of the cable under conditions of prolonged high-intensity dynamic loads caused, for example, by seismic activity.

The specified technical result is achieved in that the electric cable for control and monitoring circuits contains eight conductive cores provided with insulation of thermoplastic material, said conductive conductors are twisted in pairs to form four pairs, the aforementioned pairs of conductive conductors are twisted together to form a four-pair bundle over which is sequentially there is a belt insulation made of a polymeric material, a shield and a sheath of thermoplastic material, while the ratio of the diameter of the cable to the twisting step of the aforementioned conductive cores in a pair is from 0.04 to 0.3.

The specified technical result is also achieved by the fact that the four-pair bundle is wrapped in a spiral fastening element made of synthetic material with a pitch of not more than 300 mm.

The specified technical result is also achieved by the fact that the insulation of each conductive core has its own color.

The specified technical result is also achieved by the fact that on top of each conductive core there is a thermal barrier made of mica tape or fiberglass.

The specified technical result is also achieved by the fact that the screen is made of metal or metal-polymer.

A distinctive feature of the design of the electric cable in accordance with this utility model is the optimal selection of the pitch of the twisting of pairs of conductive wires.

Brief Description of the Drawings

In FIG. 1 shows a cross section of a cable.

Utility Model Implementation

In modern conditions, computerized control, monitoring and data transmission tools are widely used in automation systems, telemechanics, measuring and testing complexes and control systems in various fields. The reliability and safety of such systems is determined by the reliability and safety of electrically conductive equipment. One of the most responsible in terms of safety requirements is the field of nuclear energy. Products intended for operation at nuclear power plants must maintain their high functional and operational reliability under any external influences.

Recent incidents related to nuclear power facilities show that one of the most dangerous external influences is seismic activity. Equipment requirements under seismic conditions are established by various regulations, norms and rules in the field of atomic energy use (for example, Design Standards for Earthquake-Resistant Nuclear Power Plants NP-031-01).

The main reason for the loss of operability or fire safety properties of electrically conductive equipment is the destruction of protective coatings, shells, insulation, etc. The mechanics of the destruction of coatings made of polymer materials has its own laws. Destruction begins in places of the highest concentration of mechanical stresses (in places of maximum friction of surfaces) and then local fractures cover neighboring areas, causing destruction of conductive materials, cable failure or fire.

Mechanical stresses and deformations appear primarily in the contact points of the conductors, which in turn is determined by the twisting parameters and their relationship with other geometric parameters of the cable. This utility model is based on a combination of optimal twisting parameters and cable diameter.

As shown in FIG. 1, the electric cable comprises a core 3, on top of which a belt insulation 4, a shield 5 and a sheath 6 of thermoplastic material are arranged sequentially. The core 4 is made in the form of a four-pair beam formed by conductive cores 1.

The four-pair bundle is formed by twisted in pairs and equipped with insulation 2 of a polymer material conductive conductors 1.

Conducting cores 1 can be made single-wire or multi-wire. The insulation 2 and the shell 6, it is advisable to perform a halogen-free polymer composition. The screen 5 is expediently made from a metal or metal-polymer tape (for example, from an aluminum-polymer tape) with a thickness of at least 0.05 mm. Under the screen 5, it is advisable to lay a tinned copper contact wire (wire cross section is shown at 7) with a diameter of 0.3 mm to 0.6 mm.

The ratio of the cable diameter to the twisting step of the aforementioned conductive cores in a pair is from 0.04 to 0.3. It was experimentally established that the stability of the electromechanical properties of the cable under dynamic loads, especially transient attenuation, depends on the location and size of the centers of concentration of mechanical stresses. With this ratio, transient attenuation is achieved under dynamic loads on the cable and optimal mass and mechanical characteristics. When the value of the specified ratio is less than 0.04, the diameter of the core becomes unstable. In this case, the screen 5 and the sheath 6 exert uneven pressure on different sections of the conductive conductors 1, which leads to the formation of stress concentrators. At values greater than 0.3, the transient attenuation increases due to the large number of turns of conductive wires and a high degree of compression. In addition, the claimed range provides the optimal ratio of the linear mass of the cable and its tensile strength, as well as the optimal value of the flexibility of the cable.

It is advisable to perform insulation 2 of each conductive core 1 in a different color to facilitate installation and integrity testing.

Outside of each conductive core 1, a thermal barrier can be located made of mica tape or fiberglass, from 0.1 mm to 0.2 mm thick. This ensures the stability of the electromechanical parameters of the cable at high temperatures.

The belt insulation 4 may be made of a polymer material.

The cable in accordance with this utility model can be manufactured on known industrial equipment using known technologies.

The utility model works as follows.

Carry out the laying of the cable and its connection to electrical devices. The color scheme of conductive conductors and fastening elements allows you to quickly connect on long lines.

The indicated ratio of the steps of twisting the conductive conductors into pairs and the cable diameter allows us to ensure stability, primarily transient attenuation, as well as other structural, electrical, mechanical, physical and mechanical parameters of the cable and maintain its operability under the influence of earthquakes, vibrations and dynamic loads of any other origin.

Claims (5)

1. An electric cable for control and monitoring circuits, comprising eight conductive cores provided with insulation of thermoplastic material, said conductive cores twisted in pairs to form four pairs, the aforementioned pairs of conductive cores twisted together to form a four-pair bundle, on top of which a belt insulation of a polymeric material, a shield and a sheath of thermoplastic material, while the ratio of the diameter of the cable to the pitch of the twisting of the conductive wires in pairs amounts of 0.04 to 0.3. 2. The cable according to claim 1, characterized in that said four-pair bundle is wrapped in a spiral by a fastening element of synthetic material with a pitch of not more than 300 mm. 3. The cable according to claim 1, characterized in that the insulation of each conductive core has its own color. 4. The cable according to claim 1, characterized in that the outside of each conductive core is a thermal barrier made of mica tape or fiberglass. 5. The cable according to claim 1, characterized in that the screen is made of metal or metal polymer.

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