Cable lines / 02.04.2025

Cable screen temperature calculation

The screen (and core) must withstand the short-circuit (fault) current (If), taking into account its time (tf). For XLPE- and EPR-insulated cables, the temperature during a short-circuit should not exceed 250°C. In the lack of information, this temperature is applicable for both the core and the screen. However, according to IEC 61443, if the screen

Read More
Cable lines / 27.03.2025

Cable thermal stability

Modern MV-HV cable has conductive screen. Such screen, after grounding, make it possible to equalize the electric field in the cable insulation and eliminate this field outside the cable. In practice, the question arises – how to choose the screen cross-section? Cable factories have their own opinion. Let’s assume that a screen is made out

Read More
Cable lines / 20.03.2025

Cable block optimisation

Numerous cable lines running next to each other are usually assembled together into so-called pipe blocks. For example, this happens in areas near the switchgear, where up to several dozen parallel lines can be located in one place. Usually, the number of pipes exceeds the number of cables that need to be laid. Such a

Read More
Cable lines / 17.03.2025

Cable screen currents

If I hadn’t paid only 100 euros in taxes, I would be a criminal. If AC 6-35 kV networks are being massively built all over the world (for example, to connect windfarms to the grid), where each cable line has tens and thousands of euros of useless power losses in screens, then this is called

Read More
Cable lines / 12.03.2025

Cable installation errors

Cable is like a child – it’s not enough to give birth to him at the “factory”, but he must also be given to the right “school” with good “teachers”. Let’s take a closer look at the “graduation” of our cable. The photo shows the set of 110 kV cables and their terminations, and I’m

Read More
Cable lines / 06.03.2025

Induced currents of zero sequence

Single-core cables of 6-35 kV usually have a two-side grounding of the screens (“solid bonding”). This leads to the fact that in normal operation, the magnetic field of the core induces 50 Hz currents in the screens. At a given current in the core, the induced currents in the screens depend on:✅the cross-section of the

Read More
Cable lines / 03.03.2025

Cable preheating

Last week in LinkedIn, I came across a post where the cable was “preheated” with an open fire before laying. Workers “heated up” beautiful cable with open fire and at the same time cheerfully said, “How good that we have a cable with a non-flammable outer sheath”. I couldn’t get past such a terrible attitude

Read More
Overhead lines and reactors / 21.02.2025

Multifaceted transition pole

There are cable lines, there are overhead lines. However, there are also mixed lines consisting of both cable and overhead sections. On such mixed lines, the question arises as to how best to equip a transition point. There are a lot of issues there:➡️ where to place the set of cable terminations and of which

Read More
Cable lines / 12.02.2025

Bonding cable length

Let us discuss the length of the bonding cable and also such a thing as the steepness of current/voltage impulses that creates voltage drop. Industry documents suppose that the voltage in the joint can be determined as a sum of residual voltage of SVL (sheath voltage limiter) and the voltage drop across the bonding cable,

Read More
Cable lines / 06.02.2025

Bonding cable type

For high-voltage cable lines, the cross-bonding of screens is quite common. It is used not only for 110-500 kV lines, but also for 6-35 kV. The cross-bonding assumes that the six cable screens (1,2,3,4,5,6) must be removed from the three joints (A,B,C) and then connected to each other in a cross manner using a system

Read More