Electric power industry consulting
In medium voltage networks of 6-35 kV, at least the following methods of laying single-core cables in the ground are known:1️⃣ Directly in the ground;2️⃣ In the ground in a common pipe;3️⃣ In three different pipes arranged in a bundle. In 110-500 kV high voltage networks, option 2️⃣ is missing, and only options 1️⃣ and
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
Let us continue with a series of green posts on transients and surge arresters. Today let us assume that, in three-phase network, a single-phase-to-ground fault occurs, in phase A. In this case, the 50 Hz voltage on the two undamaged phases B and C will increase compared to its normal value. Compared to normal operation,
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
The main characteristics of the three-phase AC network are its voltage class, frequency, and method of neutral grounding. Speaking of voltage, there are two different voltages (the designations may depend on the country):✅ Rated voltage (let it be Ur);✅ Maximum continuous operating voltage (let it be Umcov). Both voltages are the effective value of the
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
Let us continue the series of green posts. There is such a thing as “temporary overvoltages” (TOV), and one example of such processes is ferroresonance. Ferroresonance, like ordinary resonance, occurs in circuits containing capacitances and inductances. However, unlike resonance, with ferroresonance, it is important that the inductance does not remain constant, but changes depending on
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