Cable lines - parameters / 13.06.2025

Equivalent depth of the current

There is one important concept in the calculations of power transmission lines – this is the equivalent depth of current in the ground (Dg). In symmetrical operating modes (normal mode and three-phase short circuit), there is no electric current in the ground, and this depth is not interesting to us. However, in any unbalanced modes

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Cable lines - safety / 09.06.2025

Cable line transition tower damages

One of the weak points of cable lines is cable joints and terminations. Despite all the efforts of specialists who develop and install the joints/terminations, there are still many damages. The consequences of damage will vary depending on the location features. There are at least the following typical locations:1️⃣ Joints in the ground.2️⃣ Joints in

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Cable lines - ducts / 05.06.2025

Cable duct fire

The materials of the outer sheath of cables usually differ depending on whether the cable is laid in the ground or above the ground (in places where oxygen is available). To avoid cable fires (for example, due to a short circuit), cables for open laying are provided with a non-flammable outer sheath. However, when laying

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Cable lines - screen bonding / 29.05.2025

Cable outer sheath strength

To design the cable line, we need to pass the following stages:✅ Evaluate the electrical strength of the cable outer sheath (jacket) and agree on what is the permissible voltage on the screen.✅ Select the grounding/bonding scheme of the screens (number of sections, cycles, etc.)✅ Perform the thermal calculation of the cable line and select

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Cable lines - not serious / 26.05.2025

Mistakes with cable lines

The reliability of cable lines depends on a number of factors:1️⃣ Design (including calculations);2️⃣ Production and delivery;3️⃣ Cable laying and termination/joint installation;4️⃣ Cable operation (testing, monitoring, diagnostic etc);5️⃣ Unpredictable actions of third parties. Mistakes at any of these stages can lead to serious financial losses: damage to the cable, the need to repair the damaged

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Cable lines - screen bonding / 19.05.2025

Bad cable line length

We have to design the cable length that the customer wants. However, let’s discuss which line length would be particularly inconvenient for us and why. The answer to this question depends on the voltage class and the method of neutral grounding. Today, let’s only discuss 110-500 kV networks with a grounded neutral. For such networks,

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Overvoltages and protection / 13.05.2025

Surge arresters and IEC 60099

All the experience allows the author to state that the global metal-oxide surge arrester (MOA) industry is in dire need of simple MOA application methods, but, instead it, is developing endless editions of IEC 60099, adding details to an already complex document that contains dozens of MOA characteristics. At the same time, IEC 60099 does not divide

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