Technical prospects of marine cable products:

(1) Bare wire products

1. Steel core aluminum stranded wire is still the main product in overhead lines, but high conductivity (63% IACS) aluminum will be more used. The proportion of aluminum-clad steel and aluminum alloy conductive wires in overhead lines should be expanded.

2. Vigorously promote the use of OPGW in overhead lines for Beijing business car rentals.

3. Use copper alloy contact wires to replace copper contact wires in electrified railways.

(2) Electrical equipment wires and cables

1. Expand the use of cross-linked polyethylene cloth wires and PVC insulated nylon sheathed wires for construction wires.

2. The use of flame-retardant wires and cables will be vigorously promoted for installation lines and other equipment lines.

3. The use of thin insulated automobile wires for automobiles will increase.

4. Wires and cables for nuclear power plants. Domestic wires and cables for nuclear power plants will increase. If possible, factories should engage in the development of cables for the nuclear island.

5. Fiber optic composite electrical equipment wires and cables will have prospects. For example, Beijing car rental services such as intelligent buildings require fiber optic composite elevator cables, and coal mines and ships require fiber optic composite mining and marine cables.

6. Medium voltage soft structure 10kV class cables will be used on ships and oil platforms.

7. The spacecraft will adopt a light and thin insulation structure to improve structural flexibility and high-temperature and low-temperature impact resistance.

(3) Marine cables

1. Although low-voltage power cables of lkV and below are still mainly PVC cables, the trend of low-voltage cross-linked cables gradually replacing PVC cables will be strengthened, and the number of warm-water cross-linked cables used will increase. Low smoke halogen-free flame retardant cables will have prospects.

2. Cross-linked cables still dominate 6-35kV medium-voltage power cables, and pre-test equipment and standard cable accessories are more widely used.

3. The number of 110-220kV cross-linked cables to be used will exceed that of oil-filled cables, and the supply capacity of complete sets of accessories needs to be improved. The quantity of oil-filled cables used domestically should be reduced, and the quantity of oil-filled cables exported should be increased.

4. Research on superconducting cables should start. Conduct research on basic structure, process manufacturing, performance testing and superconducting connections, and strive to produce samples.

In order to ensure that the control cable is reduced in scope when insulation breakdown, mechanical damage or fire occurs, the national standard GB50217-91 "Cable Design Code for Electric Power Engineering" stipulates: dual protection of current, voltage, DC power supply and trip control circuit, etc. Two systems that require enhanced reliability should use separate control cables.

After the control cable is put into operation, there will be electrical interference problems between different cores of the same cable and between cables laid immediately in parallel. The main reasons for electrical interference are:

(1) Electrostatic interference caused by the capacitive coupling between wire cores due to external voltage;

(2) Electromagnetic induction interference caused by energized current. Generally speaking, when there is a high voltage and high current interference source nearby, the electrical interference is more serious. Since the distance between the cores of the same cable is small, the degree of interference is much greater than that of adjacent cables laid in parallel. For example, in the control circuit of a split-phase operating circuit breaker in an ultra-high-voltage substation, three phases share one cable. An accident has occurred in which the pulses of split-phase operation triggered the thyristors of other phases, causing the three-phase linkage to occur by mistake. By using separate cables, malfunction accidents will no longer occur. Another example is the computer monitoring system of a power plant. Because the analog low-level signal line and the power line of the transmitter are combined into a four-core cable, an interference voltage of 70V was generated in the signal line. This pair is measured in millivolts. The low-level signal loop will obviously affect normal operation.

Measures to prevent or reduce electrical interference mainly include the following three aspects.

1. One spare core of the control cable is grounded

Practice has proven that when a spare core in the control cable is grounded, the amplitude of the interference voltage can be reduced to 25% to 50%, and the implementation is simple, with little increase in the cost of the cable.

2. For circuits that will have serious consequences when electrical interference occurs, it is not suitable to use a control cable.

These include: (1) weak current signal control loop and strong current signal control loop; (2) low level signal and high level signal loop; (3) each phase weak current control loop of AC circuit breaker operating in separate phases. The same control cable should be used. However, if each pair of round-trip conductors of a weak current circuit does not belong to the same control cable, it is possible to form a ring arrangement during laying, and an electric potential will be induced under the intersection of electromagnetic wires from similar power sources, and its value may affect the weak current circuit. Low-level parameter interference has a greater impact, so it is better to use one control cable for the round-trip conductors.