Medium-voltage XLPE insulated power cable is suitable for fixed power transmission and distribution lines with AC 50HZ and rated voltage of 3.6/6-26/35kV. The main function is to deliver electric energy. XLPE insulated flame retardant cable is suitable for applications where the cable is required to have flame retardant requirements.
Main technical features of the product
The medium-pressure cross-linked polyethylene insulated cable adopts a full-dry chemical cross-linking method, in which the polyethylene molecules are transformed from a linear molecular structure to a spatial network structure, and the thermoplastic polyethylene is converted into a thermosetting cross-linked polyethylene to make it mechanical. Performance, heat aging performance and environmental stress capability are improved to a large extent and have excellent electrical properties. The utility model has the advantages of high normal operating temperature of the conductor, simple structure, small outer diameter, light weight, convenient use, and the laying is not restricted by the drop. This product has reliable electrical performance, heat resistance, chemical resistance, environmental stress crack resistance, anti-aging performance, and long-term service life.
The product has a simple structure, short manufacturing cycle, easy installation and maintenance, and is not limited by the drop when laying.
Product performance standards
GB/T12706.2-2008: rated voltage 1kV (Um=1.2kV) to 35kV (Um=40.5kV) extruded insulated power cable and accessories
rated voltage 6kV (Um=7.2kV) 30kV (Um=36kV) cable
GB/T12706.3-2008: rated voltage 1kV (Um=1.2kV) to 35kV (Um=40.5kV) extruded insulated power cable and accessories
rated voltage 35kV (Um=40.5kV) cable
IEC60502-2:2005: rated voltage 6kV (Um=1.2kV) to 30kV (Um=36kV) extruded insulated power cable and accessories
rated voltage 6kV (Um=7.2kV) 30kV (Um=36kV) cable
GB/T3956-2008: Conductor of cable
GB/T19666-2005: General rules for fire-retardant and fire-resistant wire and cable
The rated voltage U0/U(Um) of the cable is: 3.6/6(7.2)-6/6(7.2)-6/10(12)-8.7/10(12)-8.7/15(17.5)-12/20( 24) -18/30 (36) kV, 21/35 (40.5) and 26/35 (40.5) kV
U0: rated power frequency voltage between conductor to ground or metal shield for cable design;
U: rated power frequency voltage between conductors for cable design;
Um: The maximum value of the "highest system voltage" that the device can use.
The rated voltage of the cable is suitable for the operating conditions of the system in which the cable is located. In order to facilitate the selection of cables, the system is divided into the following three categories:
——Class A: When any phase conductor is in contact with a ground or ground conductor, it can be separated from the system within 1 min.
——Class B: This type of system can be operated for a short time in the case of single-phase ground fault. The ground fault time should not exceed 1h according to JB/T8996-1999. For the cables included in this section, a longer fault-tolerant run time of no more than 8h is allowed under any circumstances. The total duration of any one-year ground fault should not exceed 125h.
—— Class C: Includes systems that are not Class A and Class B.
Note: When the system ground fault cannot be automatically released immediately, the excessive electric field strength added to the cable insulation during the fault will shorten the electricity to some extent.Cable life. If the system is expected to run frequently in a persistent ground fault condition, the system should be classified as Class C.
For cables used in three-phase systems, the recommended values for U0 are shown in Table 1.
2. Conductor rated working temperature
The maximum rated operating temperature of the cable conductor is 90 °C.The maximum temperature of the cable conductor does not exceed 250 °C in the event of a short circuit (maximum duration not exceeding 5 s).
3. Laying the ambient temperature
The ambient temperature during cable laying should not be lower than 0 °C, otherwise it needs to be preheated beforehand.
4. Install the bending radius
The minimum bending radius of the cable during installation is shown in Table 2.
5. Laying method
The cable is not laid with a drop limit.
Cables are allowed to be placed indoors, outdoors, in the air, and in the soil, allowing localized water to accumulate.
The cable laying method can be tunnels, pipes, cable trenches, bridges, and pipes. The armored cables are allowed to be buried directly underground, and the steel wire armored cables are allowed to be laid vertically.
Single core cables are not allowed to be laid in magnetic metal tubes.
The cable laying environment should have good heat dissipation conditions.
6. The maximum allowable traction of the conductor and the maximum allowable side pressure of the cable when laying the cable
The maximum allowable traction calculation method for conductors:
- copper conductor: F = 70 × S (N / mm2)
——Aluminum conductor: F=40×S(N/mm2)
Side pressure calculation method: P=F÷R(N/m), the maximum allowable side pressure does not exceed 3000N/m.
Where: F-traction, N
S-conductor section, mm2
P-side pressure, N/m
R-cable bending radius, m
7. Cable transportation and storage requirements
The cable reels are not allowed to lay flat.
It is strictly forbidden to drop the cable tray with cables from the height during transportation. It is strictly forbidden to damage the cable mechanically.
If the cable needs to be used in sections, the cable must be sealed with a waterproof cap to prevent water ingress.
The conductor shall comply with the first or second metallized or unplated annealed copper conductor or aluminum conductor of GB/T3956. The second conductor may also be a longitudinal water blocking structure.
The insulation should be tightly packed onto the conductor and should be easily peeled off without damaging the insulator, conductor or plating. The thickness of the insulation shall comply with the requirements of Table 6.
3. Isolation sleeve
(with armored cable) extruded on the core with polyvinyl chloride (PVC) or polyethylene (PE).
The multi-core cable is made of galvanized steel strip or galvanized steel wire, and the single-core cable used for the AC circuit uses a non-magnetic metal strip or wire. The metal strip is wrapped by a double-layer gap, and the wire is twisted by multiple concentrics.
Note: A large number of facts have proved that the single-core cable with a special structure armor (such as the magnetic isolation structure with the addition of copper wire) is used in the AC circuit, and the cable is heated to cause a large drop in the current carrying capacity, so it is not recommended.
5. Outer sheath
It is extruded on armor, insulation or cable core with ST2 type PVC sheath or ST7 type polyethylene (PE) sheathing material.
6. Finished cable logo
The outer sheath surface of the finished cable is printed with a continuous mark of the name, model, rated voltage, number of cores, nominal cross section and number of meters.