Electric power industry
The method of symmetrical components is used to calculate the normal and emergency modes of the electric network. The method represents an any mode (even asymmetric) as a composition of three separate symmetrical ones:✅ Positive sequence “1”.✅ Negative sequence “2”.✅ Zero sequence “0”. To use the method, it is important that the longitudinal impedances Z1,
The vast majority of cable lines (CL) are double-circuit. Two circuits are needed not only to increase the transmitted power, but also for reliability reasons. If one circuit turns out to be disconnected (for testing, damage locating, repair, replacement), then the second circuit can provide power supply to consumers (to load). Two modes are possible
Sometimes we have to lay our cable line (CL) along some other 6-750 kV existing lines (cable or overhead). In such cases, we have to think about the magnitude of the induced voltages on the core and screens of our CL. Such interference is caused by the magnetic field of currents passing in adjacent cable
When designing 6-500 kV cable lines, one of the important tasks is to carry out thermal calculations and select the cable core cross-section (taking into account all influencing factors). The customer gives us the current that the cable line should pass, and we tell him which combination of cable core cross-section and screen bonding type
Usually, AC cable lines are up to 10 km long. However, in some cases the length can reach 50 km or even 100 km. In such cases, the cable line has a significant capacitance, which must be charged and discharged following the sine wave of the alternating voltage of the AC network. This alternating current
Usually a cable line has one cable (one core) for each of the three phases A,B,C. However, there are cases where the number of cables per phase increases up to 6 (see photo) or even more. This may be necessary, for example, so that the line can pass the entire operating current of the supply
We hear a lot that “green transition” is impossible without cable lines. But do we know and understand cable lines that well? Unfortunately, I have to say that we do not know them very well, and so far, the cable standards and catalogues require improvement. Let me show this using the example of the longitudinal
In 6-35 kV networks, many methods of neutral grounding are known. They differ in the magnitude of the ground fault current, the magnitude of the voltage increase on two intact phases, the ability to quickly search and selectively disconnect a damaged line, and so on. Let’s discuss a different question – how does the neutral
Screen cross-bonding is an important element of many 6-500 kV cable lines built with single-core XLPE-insulated cables. Therefore, special attention should be paid to the design of the cross-bonding nodes, the specifics of their installation and operation. The screens of the main 6-500 kV high-voltage cable are removed from the cable joint using special 3-6
The distribution of the book “High Voltage Cable Lines” (dated 2024) has begun: This electronic book, dated 2024, explores the design, construction and operation of alternating current cable lines rated from 6 to 500 kV, consisting of single-core or three-core cables with XLPE insulation. It is intended for employees of design organizations and power grid companies,