What are the differences between YJV3+2 and YJV4+1 cables?

The YJV power cable  is composed of one or several soft wires, and the outer covering is covered with a light soft sheath; the cable is composed of one or several insulated wires, and the outside is covered with a tough outer layer made of metal or rubber.

As we all know, there are single-core cable and multi-core distinctions in wire and cable. Single-core cable means that there is only one conductor in an insulating layer, and multi-core means that there are multiple conductors in an insulating layer. Then there will be doubts from users who don’t know. 3+2 cores and 4+1 cores are both 5 cores. What is the difference between them? YJV3+2 and YJV4+1 cables are wires and cables.  In fact, these two kinds of wires and cables have their own characteristics.

The 3+2 and 4+1 on the YJV power cable indicate the number of cores of a cable. There are 2 or 3, 3+2, 4+1, and 5 wires that are insulated from each other in a cable, respectively Called 2-core or 3-core, 3+2 core, 4+1 core, 5 core wire.

What is the difference between YJV3+2 cable and YJV4+1 cable in the model name?

1.YJV 3+2 core

3 of the 3+2 cable is the three phase wires (L1, L2, L3 phase wires, the diameter of these three wires is large), the diameter of the wires is the same, 2 is the neutral wire and the PE wire, and one wire is used to connect the neutral wire (N in The diameter of this wire is smaller than L1, L2, L3), and one wire is used to connect to the grounding wire (PE grounding protection wire, this diameter is also smaller than L1, L2, L3).

2.YJV 4+1 core

The 4 of the 4+1 cable means that the diameter of the three phase wires is the same as the diameter of the neutral wire, 1 means that the PE ground wire has a single diameter; 4+1 means that a cable consists of 4 wires, one of which is used to connect to the live wire (L1 phase wire). ), one wire is used to connect to the neutral wire (N neutral wire), and one wire is used to connect to the ground wire (PE grounding protection wire).

The above is about the structure difference between YJV3+2 cable and YJV4+1 cable, and the difference in naming. We all know that cables are named based on models, and different models of cables are different in nature, and each model of cable has its own characteristics.

General Rubber Plastic Wire Structural Characteristics

Requirements of General rubber plastic wire:
1. Scope of application: connection and internal installation of power, lighting, electrical equipment, instrumentation and telecommunication equipment with AC rated voltage of 450/750V low voltage cable and below.
2. Laying occasions and methods: indoor open laying and communication channels, along the wall or overhead laying in tunnels; outdoor overhead laying, laying through iron pipes or plastic pipes, electrical equipment, meters and radio installations, all fixed laying; plastic The sheathed wire can be directly buried in the soil.
3. General requirements: economical and durable, simple structure.
4. Special requirements:
1) When laying outdoors, due to the influence of sunlight, rain and freezing conditions, it is required to be resistant to the atmosphere, especially sunlight aging; cold resistance requirements are required in severe cold areas;

2) In use, it is easy to be damaged by external force or flammable, and it should be worn in the occasions where it is in contact with oil. When the pipe is worn, the wire is subject to greater tension and may be scratched, so lubrication measures should be taken;
3) When used internally for electrical equipment, when the installation location is small, it should have a certain degree of flexibility, and require clear color separation of the insulated wire core, and should be matched with the corresponding connector terminals and plugs to make the connection convenient and reliable; for occasions with electromagnetic protection requirements , Shielded wires should be used;

4) For high ambient temperature occasions, sheathed cables should be used; for special high temperature occasions, heat-resistant cables should be used.

Structural features
1. Conductive core: when used for internal installation of power, lighting and electrical equipment, copper core is preferred. For large cross-section wires, it is better to use compact core; bare conductors for fixed installation generally adopt category 1 or category 2 conductor structure .
2. Insulation: Insulation materials generally use natural styrene-butadiene rubber, polyvinyl chloride (PVC) cable, polyethylene, and nitrile polyvinyl chloride compound; heat-resistant wires use polyvinyl chloride with a temperature resistance of 90°C.
3. Sheath: There are generally five types of sheath materials: polyvinyl chloride, cold-resistant polyvinyl chloride, anti-termite polyvinyl chloride, black polyethylene, and neoprene rubber.

Especially cold-resistant and outdoor overhead laying should use black polyethylene and neoprene sheathed wires.
In environments with external forces, corrosion, humidity, etc., rubber or plastic sheathed wires can be used.

Heating reason of power cable in operation

When the power cable passes through a certain load current, it will be heated. With the increase of the load current, the cable surface temperature will be higher. If it is not handled in time, the consequences can be imagined. For example: PVC cable, the core temperature of 70 degrees is considered as the upper limit, and the surface temperature will be 5-10 degrees lower. Therefore, the cable surface temperature below 60 ℃ is basically safe. Considering the power supply maintenance, of course, the lower the temperature, the better.

The heating reasons of power cable in operation are as follows:

1. Cable conductor resistance does not meet the requirements, resulting in cable heating in operation.

2. Improper selection of cable leads to too small conductor cross-section of the cable used and overload phenomenon in operation. After long-term use, the imbalance of heating and heat dissipation of the cable causes heating phenomenon.

3. If it is too close to the cable, it may cause heat dissipation when the cable is too close to the cable.

4. Poor joint manufacturing technology and loose crimping will lead to excessive contact resistance at the joint and also lead to cable heating.


5. The insulation performance of cable phase to phase is not good, resulting in low insulation resistance and heating phenomenon during operation.

6. The partial sheath damage of armored cable will cause slow damage to the insulation performance after water inflow, resulting in the gradual decrease of insulation resistance, and also the heating phenomenon during the operation of the cable.

If the cause is not found out and the fault is eliminated in time, the insulation thermal breakdown will occur after the power cable is continuously energized. This will lead to phase to phase short-circuit tripping of cables, which may cause fire in serious cases.

What is the basic structure of the cable?

One is the conductor structure.The conductor of cable is usually made of high purity copper or aluminum of certain toughness and strength with good electrical conductivity. Conductor sections are commonly used in circles and sectors. A conductor with a smaller section (less than 16 square meters) is made of a single copper wire, while a conductor with a larger section (16 square meters or more) is made of several copper wires twisted in fractional layers. When twisted, the twisted direction of the two adjacent layers is opposite.Cable structure

The second is the insulation layer of the cable.The insulation layer of cable is used to make the multi-core conductor and conductor and sheath mutually isolated, and to ensure a certain electrical compressive strength, it should have a certain heat resistance and stable insulation quality.
The thickness of the insulating layer is related to the working voltage. Generally speaking, the higher the voltage level is, the thicker the insulation layer will be, but not in direct proportion.Cable structure

Third, cable sheath.So that the cable insulation is not damaged, and to meet the requirements of various use conditions and environment, divided into inner sheath and outer sheath.Inner sheath is a protective covering covering the cable insulation to prevent the insulation from being affected by moisture, mechanical damage, light and chemical corrosive media, etc., and can also flow through short-circuit current. Common inner protective layer has non-metallic polyethylene sheath, polyvinyl chloride sheath, metal corrugated aluminum sheath and so on.Outer sheath is the protective covering layer outside the inner sheath of the cable, which mainly plays the role of mechanical strengthening and anti-corrosion. The outer sheath is usually composed of metal tape armor or wire armor plus polyvinyl chloride or polyethylene sheath.Cable structure

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