Electric power industry consulting
Counters of the impulse number were used for the previous generation of MOA – it was gapped valve-type arresters. That generation had a concept of “resource” for them because of a small thermal resource of nonlinear elements connected in series with gap. It was only 20-30 discharges of the gap, after which it was necessary
1️⃣ As you can see from the photo, the cable screens are grounded directly to the support structure, without the use of link-boxes (I marked screens with yellow lines). This kind of screens connection is not a good solution, because it creates problems for personnel during periodic tests of the cable outer sheath. Let me
The photo shows a 220 kV cable line laid in one of the Central Asian countries. During the construction of the line, cables and couplings (joints and terminations) were used of one of the world famous Asian manufacturers. After several years of operation, the cable joints gave faults one by one, and in total more
When using single-core 6-500 kV cables, various grounding schemes of screens are known. However, regardless of the scheme, it is recommended to connect cable screens to the ground at the ends of the line using special boxes. They are useful for personnel safety and convenience of testing the outer sheath of single-core cables. There are
Under the 50 Hz AC operating voltage there is a AC current inside the MOA. For a serviceable MOA, it is about 0.5 mA (some models can have up to 1 mA). If the current increases, then this is the basis for checking the MOA – this is the reasoning of those who lobby for
This is a line of voltage class 1150 kV, which was built about 35 years ago in Kazakhstan. It was a unique project for the whole world to transfer electric power of several thousand megawatts from the Ekibastuz coal basin (Kazakhstan) to the center of the USSR. However, after the collapse of the Soviet Union,
In addition to cable and overhead lines, there are mixed lines when, for various reasons, part of the line route is made as an overhead line, and part as a cable one. At the junctions of cable and air sections, special “transition points” have to be equipped. There are a huge number of transitional point
Let me pay attention to one very common mistake that can be very expensive. In the construction of a single-core cables, the main elements are the core and XLPE-insulation. The metal screen (Cu, Al) and the outer sheath of the cable are usually perceived as auxiliary elements of the cable. As a result, people carry
The photo shows the ordinary cable termination of 10 kV, which was overheated due to high currents induced in the screens. We can see traces of excessive heating at the junction of the screen with its grounding wire, caused by significant currents passing there. The quality of the screen and wire connections is a separate
The photo shows a monitor (meter) for metal-oxide surge arrester (MOA). The device combines two functions: 1️⃣ To measure the «conduction current» passing through MOA under the influence of the AC operating voltage of the 50 Hz frequency. 2️⃣ To count the «number of impulses» through MOA. Both functions are absolutely useless! I will explain