Electric power industry consulting
The previous post was about the reasons why switching lines with shunt reactors (SR) can cause damage of the line breaker B1. Theoretically, several options can be proposed to solve the problem. Let’s start with controlled switching devices (CS, see scheme). CS can be used only in cases when each phase of the breaker has
Let me please start a new series of posts about cable lines, scheduled for 2024, with a comic comparison of the cable pulling process with the fishing. This is the real story that happened a couple years ago with 110 kV cable when it was pulled in a hilly city. For that 110 kV cable,
The photo shows a 500 kV SF6 circuit breaker (B1), which was damaged during the energizing of the 500 kV overhead line. The cause of the accident was the presence of a 500 kV shunt reactor (SR) on the line, which compensated about 100% of the capacitive reactive power of the line. Let’s look at exactly
For relay protection and grid automatization, adjacent switchgears must exchange the necessary information with each other. Previously, communication was organized primarily through phase wires of an overhead line due to the high-frequency signals superimposed on currents and voltages of industrial frequency 50 Hz. In recent years, the situation has changed, and fiber-optic connections have become
The photos show the exit point of the high voltage single-core cable from the ground near the cable ternination. Please note that the cable is placed in a black single-layer corrugated pipe. What’s wrong here? 1️⃣ Corrugated pipe is not a reliable mechanical protection for high-voltage cable. For example, pay attention to the deep cuts
High-voltage cables must have a conductive metal screen (sheath). The selection of the screen cross-section is very important. Without selecting the screen cross-section (and bonding/grounding scheme), it is impossible:✅ To ensure the resistance of the cable screen to fault (short-circuit) currents.✅ To perform a thermal calculation of the cable line and select the core cross-section.
When we were little boys and girls, many of us liked:1️⃣ Sit in the sandbox and dig the sand with a shovel.2️⃣ Shoot from an imaginary space weapon.3️⃣ Play hide-and-seek with each other. In the attached video, the team of cable specialists, despite their advanced age, was quite able to return to their childhood. Why
For surge arresters (SA) of 110 kV and above, special grading rings are usually used, which, in normal operation mode, make it possible to equalize the distribution of AC 50 Hz voltage along the SA height. This distribution is important because it guarantees the absence of overheating of the SA elements (varistors), eliminates the risk
High voltage cable terminations are usually installed vertically. This allows you:✅ To ensure the absence of mechanical influences bending the termination under its own weight and the weight of the cable.✅ To ensure high-quality filling of the termination with dielectric oil (not relevant for terminations of dry-type or gas-type). However, sometimes, for various reasons, the
The photo shows the grading ring (“screen”) that remained from the damaged 110 kV metal-oxide surge arrester (SA or MOA). I’m not going to discuss now why and where the damaged SA went (flew away or just fell down on some equipment and people’s heads). Now I would like to discuss the SA screen only.