China Zhenglan Cable Technology Co., Ltd Company News

1.1 The selection of cable insulation type shall comply with the following provisions: 1 Under the operating voltage, working current and its characteristics and environmental conditions, the cable insulation characteristics shall not be less than the normal expected service life. 2 It shall be selected based on factors such as operational reliability, ease of construction and maintenance, and the comprehensive economy of the maximum allowable operating temperature and cost. 3 It shall meet the requirements of fire-proof places and shall be conducive to safety. 4 When it is clear that it needs to be coordinated with environmental protection, environmentally friendly cable insulation types shall be selected. 1.2 The selection of insulation types for commonly used cables shall comply with the following provisions: 1 The selection of insulation types for medium and low voltage cables shall comply with the provisions of Articles 1.3 to 1.7 of this Code. Low voltage cables shall use polyvinyl chloride or cross-linked polyethylene extruded insulation types, and medium voltage cables shall use cross-linked polyethylene insulation types. When it is clear that it needs to be coordinated with environmental protection, polyvinyl chloride insulated cables shall not be used. 2 Cable lines in high-voltage AC systems shall use cross-linked polyethylene insulation types. In areas with more operating experience, self-contained oil-filled cables can be used. 3 For high-voltage direct current transmission cables, non-drip-impregnated paper insulation and self-contained oil-filled types can be selected. When it is necessary to increase the transmission capacity, it is advisable to select a type constructed with semi-synthetic paper materials. Ordinary cross-linked polyethylene cables should not be used for direct current transmission systems. 1.3 For mobile electrical equipment and other circuits that are often bent or have high flexibility requirements, rubber insulation and other cables should be used. 1.4 In places where radiation is applied, cables with radiation irradiation strength such as cross-linked polyethylene or EPDM insulation should be selected according to the requirements of the insulation type. 1.5 In places with high temperatures above 60°C, heat-resistant cables such as heat-resistant polyvinyl chloride, cross-linked polyethylene or EPDM insulation should be selected according to the requirements of the high temperature, its duration and the insulation type; in high-temperature environments above 100°C, mineral insulated cables should be selected. Ordinary polyvinyl chloride insulated cables should not be used in high-temperature places. 1.6 In low-temperature environments below -15°C, cross-linked polyethylene, polyethylene insulation, and cold-resistant rubber insulation cables should be selected according to the low-temperature conditions and insulation type requirements. Polyvinyl chloride insulated cables should not be used in low-temperature environments. 1.7 In crowded public facilities and places with low-toxic flame retardancy and fire protection requirements, cross-linked polyethylene or ethylene-propylene rubber and other halogen-free insulated cables can be used. When low toxicity is required for fire protection, polyvinyl chloride cables should not be used. 1.8 Except for the cases required by Articles 1.5 to 1.7 of this Code, polyvinyl chloride insulated cables can be used for circuits below 6kV. 1.9 For 6kV important circuits or cross-linked polyethylene cables above 6kV, the type with the characteristics of inner and outer semi-conductive and insulating layers co-extrusion process should be selected.   The difference between polyethylene, polyvinyl chloride, cross-linked polyethylene, and ethylene-propylene rubber materials： The difference between the four materials 1. Polyethylene. English abbreviation PE, it is a polymer of ethylene, non-toxic. Easy to color, good chemical stability, cold resistance, radiation resistance, and good electrical insulation. 2. Polyvinyl chloride. English abbreviation PVC, it is a polymer of vinyl chloride. It has good chemical stability and is resistant to acids, alkalis, and some chemicals. It is resistant to moisture, aging, and flame retardant. The temperature when it is used cannot exceed 60°C (polyvinyl chloride will release toxic HCl smoke when burning), and it will harden at low temperatures. Polyvinyl chloride is divided into soft plastics and hard plastics. 3. Cross-linked polyethylene. XLPE in English is an important technology to improve the performance of PE. PE modified by cross-linking can greatly improve its performance, not only significantly improving the mechanical properties, environmental stress cracking resistance, chemical corrosion resistance, creep resistance, and electrical properties of PE, but also significantly improving the temperature resistance level, which can increase the heat resistance temperature of PE from 70°C to above 90°C, thereby greatly broadening the application range of PE. At present, cross-linked polyethylene (XLPE) has been widely used in pipes, films, wire and cable materials, and foam products. 4. Ethylene propylene rubber (EPR). The full name is cross-linked ethylene-propylene rubber, which has oxygen resistance, ozone resistance and partial discharge stability; the dielectric loss factor is large, so it is only used in power cable lines with voltage levels below 138kV. Due to the good water resistance of EPDM, EPDM cables are suitable for submarine cables, and because EPDM has good softness, it is more suitable for laying in mines and ships.

The shielding layer in the control cable has the following main functions: ‌ Electromagnetic interference suppression‌: The shielding layer can shield the electromagnetic field generated when the cable is powered on in the insulated core, reduce the electromagnetic interference to the outside world, and limit the impact of the external electromagnetic field on the inside‌.   ‌Grounding protection‌: If the cable core is damaged, the leaked current can flow into the grounding grid through the shielding layer, which plays a role in safety protection and prevents safety hazards caused by current leakage‌.   ‌Reduced signal leakage‌: The shielding layer can prevent the leakage of internal signals in the cable and prevent the signal from interfering with other nearby cables or equipment‌.   ‌Improved durability‌: The metal shielding layer can prevent the cable from physical damage, such as extrusion, stretching or bending, thereby extending the service life of the cable‌.   Zhenglan Cable can supply you with 450/750V, 0.6/1KV various equipment control cable, welcome your inquiry.  

What are the rated voltage levels of power cables, and how to determine them according to different places? 1. The rated voltage levels of power cables are mainly divided into the following categories: 1-1. Low-voltage cables: suitable for fixed laying on AC 50Hz, rated voltage 3kV, and below transmission and distribution lines for transmitting electric energy. 1-2. Medium and low voltage cables: generally refer to cables of 35kV and below, including polyvinyl chloride insulated cables, polyethylene insulated cables, and cross-linked polyethylene insulated cables. 1-3. High-voltage cables: generally 110kV and above, using polyethylene cables and cross-linked polyethylene insulated cables. 1-4. Ultra-high voltage cables: voltage levels between 275 and 800 kV. 1-5. UHV cables: voltage levels of 1000 kV and above. 2. When determining the rated voltage level of cables according to different places, the following factors need to be considered: 2-1. System nominal voltage: the rated voltage of the cable must be greater than or equal to the rated voltage of the network in which it operates. For example, if the nominal voltage of the system is 220/380V, the rated voltage of the cable should meet this requirement. 2-2. Maximum operating voltage: The maximum operating voltage of the cable shall not exceed 15% of its rated voltage. 2-3. Technical requirements: When selecting a cable model, the development of the cable industry and technical policies of various countries should be taken into account while meeting the technical requirements of the cable laying occasion.

Dear Customer Thanks for visiting our website. Due to China's National Day Holiday is coming, we will be on holiday from 1st(Tuesday) to 7th(Monday). Work resume from 8th(Tuesday). During holiday, we will have limited access to email and may reply you late. Kindly ask for your understanding. Zhenglan Cable Technology Co., Ltd September 30th, 2024

Dear Customers   Here comes Chinese traditional Mid Autumn Day festival. Kindly note we will be on a 3-day Mid-Autumn Day holiday from September 15th(Sunday) to September 17th(Tuesday). Work resume from Wednesday.    During holiday, work will stop temporarily. For all the messages you left, we wonnot be cable to reply untill after holiday. Thanks for your kind understanding. Once come back, we will contact you at our first time.   Hope everyone will have a good time.    Zhenglan Cable Technology Co., Ltd  

Shielded cable has the word "shielded" in it. As the name implies, it is a cable with the ability to resist external electromagnetic interference formed by adding a shielding layer to the transmission cable. The so-called "shielding" in the cable structure is also a measure to improve the distribution of the electric field. The cable conductor is made of multiple strands of wires twisted together. It is easy to form an air gap between it and the insulation layer. The surface of the conductor is not smooth, which will cause electric field concentration. 1. Cable shielding layer 1). Add a shielding layer of semi-conductive material on the surface of the conductor. It has the same potential as the shielded conductor and has good contact with the insulation layer, thereby avoiding local discharge between the conductor and the insulation layer. This layer of shielding is also called the inner shielding layer. There may also be gaps at the contact between the insulation surface and the sheath. When the cable is bent, the insulation surface of the oil-paper cable is prone to cracks. These are factors that cause local discharge. 2). Add a shielding layer of semi-conductive material on the surface of the insulation layer. It has good contact with the shielded insulation layer and has the same potential as the metal sheath, thereby avoiding local discharge between the insulation layer and the sheath. To make the conductive core and the insulating electric field uniform, medium and high voltage power cables of 6kV and above generally have conductor shielding layers and insulating shielding layers, and some low voltage cables do not have shielding layers. There are two types of shielding layers: semi-conductive shielding and metal shielding. 2. Shielded cable The shielding layer of this type of cable is mostly made of metal wires woven into a mesh or metal film, and there are many different ways of single shielding and multi-shielding. Single shielding refers to a single shielding net or shielding film, which can wrap one or more wires. Multi-shielding means multiple shielding nets and shielding films are in one cable. Some are used to isolate electromagnetic interference between wires, and some are double-layer shielding to enhance the shielding effect. The mechanism of shielding is to ground the shielding layer to isolate the induced interference voltage of the external connection to the wire. 1). Semi-conductive shielding The semi-conductive shielding layer is usually set on the outer surface of the conductive core and the outer surface of the insulating layer, respectively called the inner semi-conductive shielding layer and the outer semi-conductive shielding layer. The semi-conductive shielding layer is composed of a semi-conductive material with very low resistivity and thin thickness. The inner semi-conductive shielding layer is to even out the electric field on the outer surface of the core, and avoid partial discharge between the conductor and the insulation due to the uneven surface of the conductor and the air gap caused by the twisting of the core. The outer semi-conductive shielding layer is in good contact with the outer surface of the insulation layer, and is at the same potential as the metal sheath, avoiding partial discharge with the metal sheath due to defects such as cracks on the cable insulation surface. 2). Metal shielding For medium and low voltage power cables without metal sheaths, in addition to the semi-conductive shielding layer, a metal shielding layer must be added. The metal shielding layer is usually wrapped with copper tape or copper wire and mainly plays the role of shielding the electric field. Because the current passing through the power cable is relatively large, a magnetic field will be generated around the current. In order not to affect other components, the shielding layer can be added to shield this electromagnetic field in the cable. Moreover, the cable shielding layer can play a certain role in grounding protection. If the cable core is damaged, the leaked current can flow along the shielding layer like the grounding grid, playing a role in safety protection. It can be seen that the role of the cable shielding layer is still very large.