Electric power industry consulting
Sometimes I envy overhead line (OHL) specialists because it’s always easy for them to show what they are doing. They walk down the street with family and friends and say – look, there is a tower (pylon, pole), there are wires hanging, and shield wires above them, and birds that have built nests. But what
Single-core cables with XLPE insulation are massively used in 110-500 kV networks. Solid (two-sided) grounding of the screens of such cables leads to negative consequences, and therefore, as a rule, for screens should be used:✅Single-point grounding (see diagram)✅Cross-bonding. In both schemes, voltages may occur on screens relative to the ground caused by interference from the
The electrical capacitance of cables directly affects the arrangement of medium-voltage 6-35 kV networks with an isolated neutral, as well as issues of reactive power compensation of 110-500 kV networks. Let’s talk about what kind of capacitance the modern cables have. THE FIRST.When cables with cross-linked polyethylene (XLPE) insulation appeared, we were told that these
In 6-500 kV networks, single-core cables with XLPE insulation are widely used. Such cables have conductive screens. In such screens, if they are grounded at both ends, AC 50 Hz currents are induced in normal mode and active power losses occur. This leads to additional heating of the XLPE, a decrease in the long-term permissible
The reliability of cable lines is catastrophically dependent on the quality of installation work. Therefore, we can only be glad that there are a large number of experts all over the world who do their job accurately and precisely. Certainly, some of them may even be called as perfectionists. However, in my opinion, there is
At the ends of the cable line, there are cable terminations. Metallic screens of cables are removed from terminations to the outside, where they are connected in accordance with selected bonding/ grounding scheme. For example, the figure shows the high voltage cable line with one-sided grounding of screens. To have this scheme, metallic screens, with
Designing a cable line is an interesting process that resembles moving in a circle. The fact is that in order to select cables, we need the correct values of the short-circuit current (1.1) and the steady-state current (1.2). Such currents can only be calculated using information about the impedances of the cable line (R1, X1,
Let me please start a new series of posts about cable lines, scheduled for 2024, with a comic comparison of the cable pulling process with the fishing. This is the real story that happened a couple years ago with 110 kV cable when it was pulled in a hilly city. For that 110 kV cable,
High-voltage cables must have a conductive metal screen (sheath). The selection of the screen cross-section is very important. Without selecting the screen cross-section (and bonding/grounding scheme), it is impossible:✅ To ensure the resistance of the cable screen to fault (short-circuit) currents.✅ To perform a thermal calculation of the cable line and select the core cross-section.
High voltage cable terminations are usually installed vertically. This allows you:✅ To ensure the absence of mechanical influences bending the termination under its own weight and the weight of the cable.✅ To ensure high-quality filling of the termination with dielectric oil (not relevant for terminations of dry-type or gas-type). However, sometimes, for various reasons, the