Recommendations for BTLY cable cross-section selection

1. Select the cross section according to the temperature rise of the core
When the load current is passed, the core temperature does not exceed the long-term working temperature allowed by the cable insulation. That is to say, select according to the allowable current-carrying capacity.
Suggestion: The cable passes through different heat dissipation conditions. The corresponding core operating temperature will be different, and the section should be selected according to the area with severe heat dissipation conditions (usually no more than 1 meter).


2. Select the cross section according to the allowable range of voltage loss
When the terminal voltage of the electrical equipment actually deviates from the rated value, its performance will be affected, and the extent of the impact will be determined by the magnitude and duration of the voltage deviation.
Suggestion: The voltage loss increases due to the sharp rise of the core temperature during fire. The voltage loss should be calculated according to the fire conditions to ensure the continuous operation of important equipment. Due to the excellent heat insulation and heat dissipation characteristics of BTLY products, it is only necessary to enlarge the cable selected according to the normal situation by one to two. Usually, it can meet the condition that the voltage deviation under fire conditions is not more than -10%.
Three, select the cross section according to the economic current
The total cost during the economic life is small. That is, the initial investment and the cost of line loss during the economic life are small.
The so-called economic current is the working cable (range) corresponding to the applicable cross-section (range) during the life of the cable, the sum of investment and conductor loss costs. For details, please refer to “Low Voltage Cable Economic Current Density Range Table”.


Suggestion: BTLY products should have good heat dissipation characteristics. If the cross section is selected according to the temperature rise of the core, the selection can be reduced by one level. But taking into account the economic current factor. Therefore, it is not recommended. If selected in accordance with the routine, the line loss will be reduced by 4-7%, which is of great economic significance.
Fourth, the selection of the cross section of the neutral power cable and the ground wire
(1) In a single-phase two-wire circuit, regardless of the size of the phase wire cross section, the neutral wire and ground wire should be the same cross section as the phase wire.
(2) In the three-phase five-wire power distribution system, the allowable current carrying capacity of the neutral wire and ground wire should not be less than the sum of the large unbalanced load current and harmonic current in the line. When the phase wire core is not larger than 16mm2, the neutral wire and ground wire should have the same cross-section as the phase wire. When the phase wire core is larger than 16mm2, if the neutral wire current is small, the cross section of the phase wire can be selected, but it should not be less than 50% of the phase wire cross section and not less than 16mm2.
Suggestion: Use the aluminum metal sheath in the BTLY cable as the grounding core. The aluminum pipe grounding wire is connected by a dedicated connector, and the connection is firm and reliable. The equivalent resistance of the aluminum tube section of the BTLY cable meets the grounding needs of the corresponding copper core

Advantages of BTTZ rigid mineral insulated cable

Due to the special structure of BTTZ rigid mineral insulated cables, it has some characteristics different from traditional cables; it is also the most superior fire resistance characteristic of mineral insulated cables.
Advantages of BTTZ rigid mineral insulated cable
1) Completely fireproof BTTZ cable itself does not burn at all, and it will not cause a fire source at the same time. Even in the case of flame barbecue, as long as the flame temperature is lower than the melting point of copper, the cable can be used without replacement after the flame is eliminated. In the case of being grilled by flames, no toxic smoke and gas will be produced.


2) Strong overload protection capability When the line is overloaded, the cable will not be damaged as long as the heat does not reach the melting point of copper. Even if the breakdown occurs instantaneously, the magnesium oxide crystal at the breakdown will not form carbides. After the overload is eliminated, the cable performance will not change, and normal use can still be continued.
3) High working temperature Since the melting point of the insulating layer of magnesium oxide crystal is much higher than the melting point of copper, the maximum normal working temperature of the cable can reach 250°C, and it can continue to operate at a temperature close to the melting point of copper of 1083°C in the short term.
4) Good anti-corrosion and explosion-proof performance. As the seamless copper tube is used as the sheath, the BTTZ cable has the performance of waterproof, moisture, oil and some chemical substances. The copper tube has considerable mechanical strength, so it has better explosion-proof performance.


5) Long service life BTTZ cables are all made of inorganic materials, so there is no insulation aging, and the service life can reach more than 3 times that of ordinary cables.
6) Greater flexibility in laying BTTZ cables can be laid on the bridge with ordinary cables, and can also be laid with special brackets, which is more flexible than ordinary cable laying. It also saves the investment in cable bridges and reduces the overall cost of the project.

What are the functions of ACSR cables?

There are too many types and specifications of cables, and if you explain them carefully, it will be very cumbersome. Therefore, today we mainly understand one of them: “flexible fireproof cable”. If you are not a professional, this may sound strange. But it is obvious from the name that this is a flexible cable. This kind of cable has the function of fire prevention; also known as mineral insulated cable, it has the advantages of good flexibility, excellent shielding performance, corrosion resistance, strong practicability, and long service life. It is widely used in demanding occasions.
Flexible fireproof cable function
1. Good flexibility: the cable can be coiled on the cable tray with a bending radius ≤ 20D (D is the outer diameter of ACSR  cable).
2. Large cross-section: the cross-section of single-core cable can reach 1000mm, and the cross-section of multi-core cable can reach 240mm.
3. Long continuous length: Whether it is a single-core cable or a multi-core cable, its length can meet the requirements of the power supply length, and each continuous length can reach 1000m.
4. Corrosion resistance: Organic insulated fire-resistant cables sometimes need to wear plastic pipes or iron pipes, plastic pipes are easy to become brittle, iron pipes are easy to rust, fire-resistant cables with copper sleeves do not need to wear pipes, and copper sleeves have good corrosion resistance此图像的alt属性为空;文件名为abc-cable-full-form.jpg
5. Good shielding performance: Put the fireproof cable on the same shaft as the information cable and control cable. Under the shield of the copper sheath, it will not interfere with the information transmitted by the signal cable and control cable.
6. Excellent fire resistance: its fire resistance not only meets the requirements of the national standard GB12666.6 A 950℃ and 90min, but also meets the test requirements of A grade 650℃ 3h, B grade 750℃ 3h and C grade 950℃ British bs6387-1994 3 hours specified in At the same time, it can withstand the water spray and mechanical shock during the combustion process.
7. Safe and reliable: fireproof cables can usually supply power in flames, reducing fire losses, especially for personal safety, which is particularly reliable. Its copper sheath is an excellent conductor and is the best grounding PE wire. Continuous use within the range improves the sensitivity and reliability of grounding protection.
8. Long service life: Inorganic insulating materials are resistant to high temperatures and not easy to age. Its service life is many times that of organic insulated cables.
Each side of the flexible fireproof cable has a relatively large advantage, and it will also have a higher utilization rate for different environments. If you need to use cables and wires in your life, you can look at one of the advantages of flexible fire-resistant cables and see if they can be used and needed. Of course, we must also grasp the comprehensive consideration of psychological choices when buying, the most appropriate is the best.

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

If there are related problems, we can communicate with each other.