Electric power industry consulting
Before putting the cable line into operation (and then periodically during operation), the integrity of the outer sheath of cables should be checked. The procedure consists of the following steps:1️⃣ Disconnect the line from the network (if it was in operation).2️⃣ Disconnect the SVLs from the link boxes.3️⃣ Unground cable screens at both sides of
Some companies like to talk about successful projects, and we know that there are really a lot of such projects, and this is very important for our industry. However, successful projects do not teach us much, and, in fact, it is much more interesting to study the mistakes that were made during the realization of
For medium voltage (MV) line, usually, screens of single-core cables are grounded at both sides. Let us assume that we have two separate MV lines, differing in the mutual arrangement of three single-core cables:Line 1️⃣ – trefoil;Line 2️⃣ – in row. In the conditions of the example, according to the book, we get the following
One of the ways to reduce lightning outages of overhead lines (OHL) is to place surge arresters (SA) on problematic sections of the line. However, there is always a risk of damage to the SA itself which creates a new problem. For example, damage can happen for one of the following reasons:✅ Lightning can transfer
Electrical parameters of cables are an important topic. For each line, it is necessary to determine the longitudinal resistance (R) and inductance (L), as well as the transverse capacitance (C), and all these parameters (R,L,C) should be found not only in a positive sequence, but also in a zero sequence. For overhead lines, these parameters
It has always been obvious to me that in terms of thickness, there are two types of outer sheath of high voltage (HV) and extra-high voltage (EHV) cables:✅ Ordinary sheath – it has a thickness of about 5 mm.✅ Reinforced sheath – it has a thickness of about 6-7 mm.However, when I started trying to
We know that the screen’s cross-bonding is an effective way to deal with induced currents and losses in the screens of 6-500 kV cable lines (CL). The use of cross-bonding allows not only to save on losses (dozens of thousands of euros annually), but also to increase the permissible core current of the cable line,
It is not enough to have money to buy a good cable. It is also important to find the time and knowledge to make the necessary calculations and select the best way to lay a cable line, taking into account the screen bonding type. Today, let’s look at a simple calculation example of a double-circuit
For lines with single-core cables, there is a problem of selecting the optimal screens’ bonding type. It is especially relevant for 110-500 kV lines, where grounding of screens on both sides is almost prohibited, and 99% of lines have either grounding of screens on one side or cross-bonding of screens. In both cases, it is
In cable catalogues, in addition to the main types of cables, there are simplified recommendations on cable selection. They are given as a table with capacity currents for basic laying conditions (Ib), as well as a series of 5-8 additional tables with various correction factors (K). It is important to note that the system of