Electric power industry consulting
If the cable insulation is damaged, the current in the cable core (Ic) and the current in the cable screen (Is) can reach the value of the network short-circuit current. One of the important steps in selecting a cable core and screen is to check their resistance to short-circuit (fault) currents, taking into account the
AC 50/60 Hz power cables can be divided into two main groups:✅ single-core cables;✅ three-core cables. 1️⃣ Single-core cables, when bonding screens on both sides, have closed circuits of screens. The core currents (Ic) by their magnetic field induce AC 50/60 Hz currents in the screens (Is) – they are called circulating. Currents pass through
The cable industry does not stand still and is constantly developing. New materials, new types of cables and cable products, new methods of design and calculation are emerging. However, some things in the cable industry remain unchanged from year to year – we are talking about cable drums (reels). All over the world, in the
The calculation of cable pulling forces is one of important section of the design documentation. It assumes at least the following calculations:✅ cable pulling forces (should be no more than 30 N/mm2 for a cable with an aluminium core and no more than 50 N/mm2 for a cable with a copper core);✅ pressure on the
In 6-35 kV network, suppose we have busbars ABC, with two lines, and a ground fault has occurred in phase A of a line (1). In case of isolated neutral, the ground fault current (Igf) is determined by the EMF (Ea) and the capacitances of all network to the ground, and therefore it is a
HVDC projects can be very roughly divided into two types:1 – subsea;2 – underground.The former ones are practically hidden from us, and all we see is a cable laying vessel on the surface of the water. The second ones are more open, have many photos, which I propose to discuss today (only for the purpose
It is believed that “we cannot have a closed contour of magnetic material around an AC single-core cable”. However, in practice, there are issues with the application of such a rule. For example, would the following contours be dangerous?➡️ it does not tightly cover the cable, but has large transverse dimensions;➡️ it has a side
When applying insulation, it is necessary to keep the high voltage cable in an upright position for a certain time to avoid ovalization and other negative effects. If we know the recommended time, then we understand that the required height of the extrusion tower will be proportional to the desired cable production speed. Hence the
Cable couplings are one of the places where cable line damage often occurs. There are many different types of couplings, but most of them can be classified into one of two categories:✅ Cable terminations;✅ Cable joints. Cable terminations are placed above the ground and can be subjected to periodic inspection, which is a good thing.
Today we will not talk about alcohol (“bar”), but about a conductive element called:✅ equipotential bar (bar, bus);✅ earth continuity conductor (ECC). Questions arise:1️⃣ why do we need such a bar;2️⃣ how to provide equal distances from the bar to all phases A,B,C;3️⃣ how to calculate the optimal bar material and cross section (Fb). Unfortunately,