China Zhenglan Cable Technology Co., Ltd Company News

1. Low resistivity: the resistivity of aluminum core cable is about 1.68 times higher than that of copper core cable.   2. Good ductility: the ductility of copper alloy is 20 ~ 40%, that of electrical copper is more than 30%, and that of aluminum alloy is only 18%.   3. High strength: the allowable stress of copper is 7 ~ 28% higher than that of aluminum at room temperature. Especially the stress at high temperature, the difference between the two is very far.   4. Fatigue resistance: aluminum is easy to break after repeated bending, while copper is not. In terms of elasticity index, copper is also about 1.7 ~ 1.8 times higher than aluminum. (low voltage power cable, medinum voltage power cable)   5. Good stability and corrosion resistance: copper core is resistant to oxidation and corrosion, while aluminum core is vulnerable to oxidation and corrosion.   6. Large current carrying capacity: due to low resistivity, the allowable current carrying capacity (maximum current that can be passed) of copper core cable with the same section is about 30% higher than that of aluminum core cable   7. Low voltage loss: due to the low resistivity of copper core cable, when the same current flows through the same section. The voltage drop of copper core cable is small. The same transmission distance can ensure high voltage quality; Under the condition of allowable voltage drop, the transmission of copper core cable can reach a long distance, that is, the power supply coverage area is large, which is conducive to network planning and reduce the number of power supply points.   8. Low heating temperature: under the same current, the heating capacity of copper core cable with the same section is much smaller than that of aluminum core cable, making the operation safer. (Aluminum conductor steel reinforced, ACSR)   9. Low energy consumption: due to the low resistivity of copper, compared with aluminum cable, the power loss of copper cable is low, which is obvious. This is conducive to improving the utilization rate of power generation and protecting the environment.   10. Oxidation resistance and corrosion resistance: the connector of copper core cable has stable performance and will not cause accidents due to oxidation. The joint of aluminum core cable is unstable, and accidents often occur due to the increase of contact resistance and heating due to oxidation. Therefore, the accident rate is much higher than that of copper core cable.   11. Convenient construction: The copper core has good flexibility and small allowable bending radius, so it is convenient to turn and pass through the pipe; The copper core is anti fatigue and not easy to break after repeated bending, so the wiring is convenient; The copper core has high mechanical strength and can bear large mechanical tension, which not only brings great convenience to the construction and laying, but also creates conditions for mechanized construction. (overhead insulated cable, electrical control cable)

Dear Customer, Happy new year!!!   We will be on traditional Chinese lunar new year Spring Festival Holiday from January 29th to February 6th. Work resume from February 7th(Monday). During holiday, all work maybe affected somehow and we may have limit access to email. So for any delay of response, kindly ask for your understanding.   Hope you all have a happy time with your family.   Zhenglan Cable Technology Co., Ltd 2022-01-27

1. The systems used are different. DC cables are used in rectified DC transmission systems, and AC cables are often used in power frequency (domestic 50Hz) power systems. 2. Compared with the AC cable, the power loss in the transmission process of the DC cable is smaller. The power loss of the DC cable is mainly the DC resistance loss of the conductor, and the insulation loss is small (the size depends on the current fluctuation after rectification); while the AC resistance of the low-voltage AC cable is slightly larger than the DC resistance, and the high-voltage cable is obvious, mainly because Proximity effect and skin effect, the loss of insulation resistance accounts for a large proportion, mainly the impedance generated by capacitance and inductance. 3. High transmission efficiency and small line loss. 4. It is convenient to adjust the current and change the direction of power transmission. 5. Although the price of converter equipment is higher than that of transformers, the cost of using cable lines is much lower than that of AC cables. The DC cable has positive and negative poles, and the structure is simple; the AC cable is three-phase four-wire or five-wire system, which requires high insulation safety and complex structure, and the cable cost is more than three times that of the DC cable. 6. DC cables are safe to use 1) Due to the inherent characteristics of DC transmission, it is difficult to generate induced current and leakage current, and it will not cause electric field interference to other cables laid in the same way. 2) The single-core laying cable will not affect the transmission performance of the cable due to the hysteresis loss of the steel structure bridge. 3) It has higher current interception capability and over-interruption protection capability than DC cables of the same structure. 4) Direct and alternating electric fields of the same voltage are applied to the insulation, and the direct electric field is much safer than the alternating electric field. 7. The installation and maintenance of the DC cable are simple and the cost is low.

The Christmas holiday is coming near . We would like to extend our warm wishes for the upcoming holiday season and would like to wish you and your family a Merry Christmas and a prosperity in the year ahead   Zhenglan Cable Technology Co., Ltd will continue to give you our best products and excellent service. Thank you for your support and help along the way. Hope the next year is a prosperous and harvest year for both of us!  Regards

1. The principle of wire selection The conductor and ground wires of power transmission lines operate in the wilderness, mountainous areas or the edge of lakes and seas for a long time, and need to withstand the effects of external loads such as wind and ice, drastic changes in temperature and attack by chemical gases, etc., and are also subject to national resources and line costs And other factors. Therefore, in the design, especially for large spans, the material and structure of the wires must be carefully selected. Generally, the following principles should be considered when selecting the material and structure of the wire: ⑴ The conductor material should have high conductivity. However, considering national resources, copper wires should not be used in general. ⑵The conductor and ground wire should have high mechanical strength and vibration resistance. ⑶ The conductor and ground wire should have certain chemical resistance and oxidation resistance. ⑷ When choosing the wire material and structure, in addition to meeting the transmission capacity, the cost of the line should be economical and technically reasonable. 2. Selection of wire cross section The cross section of the overhead transmission line conductor is generally selected according to the economic current density, and should be checked according to the heating conditions, voltage loss, mechanical strength and corona in the event of an accident. When necessary, it is determined through technical and economic comparison; but for lines of 110KV and below, corona is often not the decisive factor in selecting the conductor cross section. 1) Choose the wire section according to the economic current density According to the economic current density to select the transmission capacity used for the conductor cross-section, the development plan of the power system should be considered for 5-10 years after the line is put into operation. In the calculation, the maximum load that frequently recurs under the normal operation mode must be adopted. But when the system is not clear, care should be taken not to make the wire cross section too small. 2) Check the cross-section of the wire according to the corona condition With the continuous increase of operating voltage in my country, the probability of corona and discharge of wires, insulators and fittings has increased. For the cross-section of wires of 220KV and above voltage lines, corona conditions often play a major role. The corona generated by the wire will bring about two undesirable consequences: ① It increases the power loss of the power transmission line; ② It interferes with radio communication and carrier communication. Regarding the corona loss, if the corona loss of the transmission line is directly calculated, the advantage is that the concept of quantity is very clear, but the disadvantage is that the calculation is cumbersome. This method is rarely used at present. It tends to be measured by the ratio of the maximum working electric field strength Em (unit: KV/cm) of the wire to the critical electric field strength E0 of the overall corona. The ratio of Em/E0 should not be greater than 80%-85%.

Elastic coefficient is also called elastic modulus. Elastic modulus is not only an important factor affecting cable stiffness, but also an important physical quantity affecting the operating tension of overhead wire and cable. The elastic modulus of overhead conductor is not only related to the material, but also closely related to the structure of conductor, such as the number of strands of conductor and the process parameters of strand.  The exact elastic modulus of conductor should be determined by tensile test, so it is often said that there are initial and final values, while the test report often only gives "measured values".   The coefficient of expansion is sometimes called linear elasticity, which refers to the percentage of the change in the length of the material for every 1 ℃ change in temperature, also known as the coefficient of linear expansion. When the temperature of a solid substance changes by 1 ℃, the ratio of the change of its length to its length at 0 ℃ is called "coefficient of linear expansion". Due to different substances, the linear expansion coefficient is also different, and its value is also related to the actual temperature and the reference temperature selected when determining length 1. However, because the linear expansion coefficient of solid changes little, it can be ignored, and a is regarded as a constant independent of temperature.