Electric power industry consulting
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
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
Dear colleagues, let me please start a series of “green posts” on electromagnetic transients and protection against them. In general, I have to admit that there are too many experts in this area in the world, and it seems to me sometimes, they are ready to fight brutally for their right to exist under this
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
Lightning processes are statistical processes. It is hardly possible to study such processes by considering a lightning strike to the line with specific parameters (current, front) or by considering a specific lightning wave coming from the line to the switchgear. To calculate the probability, I normally use ATP/EMTP, which has been changed for the convenience
To protect the transformer from lightning surges, the metal-oxide arrester (MOA) is often placed directly at its bushings, at a distance of no more than 2-3 m. This creates an impression that the transformer will be fine. In fact, this is a false impression, and the effect on the windings depends not only on the