2026 - Cable lines / 14.01.2026

Automatic reclosure of the cable line

If a short circuit occurs on the line, the line is switched off. However, what to do next depends on the type of the line:1️⃣ overhead line;2️⃣ cable line;3️⃣ mixed line, having both overhead and cable sections. 1️⃣ OVERHEAD LINEFor an overhead line, up to 60-90% of faults are associated with short-term overlaps of air

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2026 - Cable lines / 01.01.2026

Sealing cap for cable

For modern cables of 6-500 kV voltage classes, cross-linked polyethylene (XLPE) insulation is the most common. The properties of XLPE are such that if water molecules penetrate the insulation, they become a source of electric field distortion there, which contributes to the development of insulation defects called “water trees”. The appearance of water inside the

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Cable lines - ducts / 17.12.2025

Cable protection in pipes

It is quite common to lay cables underground in pipes (let me please not use the word duct or conduit). There are probably three main ways to place pipes in the ground:➡️ at the bottom of a trench;➡️ in the borehole prepared by horizontal-directional drilling (HDD);➡️ in the channel prepared by puncturing the ground. The

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Cable lines - screen selection / 27.11.2025

Material of cable screen

Copper (CU) and aluminium (AL) are the two main materials for the current-carrying parts of the cable, that is, for the core and the screen. The features of AL are as follows:1️⃣ AL is up to 3-4 times cheaper than CU.2️⃣ AL is 3 times lighter in weight than CU.3️⃣ AL resistivity is 1.6 times

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Cable lines - screen bonding / 20.11.2025

Where screen currents come from

Three-phase AC 50/60 Hz cable lines have magnetic fields (H) of core currents A,B,C. In normal operation, the currents A,B,C are equal to each other and have a 120° shift, so it seems that the magnetic fields A,B,C should compensate each other. However, this is not happening well, and as a result, the line has

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Cable lines - joints and terminations / 15.11.2025

Damage to cable termination

An interesting case occurred at one of the medium-voltage facilities. The 10 kV busbars were fed by a powerful 110/10 kV step-down transformer. To reduce short-circuit currents on 10 kV side, reactors were installed there between the transformer and 10 kV busbars. The transformer and reactor were connected using single-core cables (about 50 m length,

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