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Before discussing the actual comparison, let’s look at the different media used in circuit breakers. These are air, oil, and SF6 gas. Nowadays, engineers have also developed some other gaseous media like compressed air, C4-FN mixtures (C4-FN/CO2 or C4-FN/N2), C5-FK mixtures (C4-FK/air or C4-FK/CO2), and pure N2 or N2/CO2 mixtures as insulating mediums. Certainly, some … Read more
We shall cover the constructional details of a vacuum interrupter along with its function, how it facilitates arc quenching, etc. Introduction to Vacuum Circuit Breakers Before entering into the detailed discussion about the vacuum interrupter, let us have a look at the basic concept of vacuum circuit breakers. A vacuum interrupter, which we also call … Read more
A lightning arrester is a protective device used in electrical power systems, buildings, communication systems, and other infrastructure to safely divert high-voltage surges caused by lightning strikes or switching events to the ground for preventing damage to equipment. Actually, a lightning arrester is a device connected between the line and ground. It remains non-conductive under … Read more
In this article, we shall explore the lightning arrester ratings. The article includes rated voltage, MCOV, discharge current, residual voltage, energy absorption, and many more. Lightning Arrester Ratings based on Voltage How to Select the Lightning Arrester Ratings based on Voltage? For that, we have to consider two conditions. These are the effectively earthed condition … Read more
Why was the gapless ZnO lightning arrester developed over the valve-type lightning arrester? In a valve-type lightning arrester, we connect spark gaps in series with non-linear resistors. This is necessary because silicon carbide (SiC) has a relatively low non-linearity coefficient (α ≈ 5–7). As a result, the knee point in the V–I characteristic of an … Read more
Zinc oxide has a semiconducting nature. Zinc oxide (ZnO) is an n-type semiconductor. An n-type semiconductor is a material in which loosely bound electrons are available. However, zinc oxide (ZnO) is not like conventional semiconductors such as germanium or silicon. In germanium or silicon semiconductors, these extra electrons come from dopants. But in ZnO, no … Read more
We also refer to a Gas Insulated Switchgear (GIS) as a Gas Insulated Substation. Why is GIS the Future of High-Voltage Power Systems? There are several reasons for preferring a Gas-Insulated System (GIS) over an Air Insulated System (AIS). Constructional Details of Gas Insulated Substation (GIS) A GIS consists of several key modules, each performing … Read more
Insulators Used in Overhead Transmission Lines In overhead transmission lines, insulators support the conductor on metallic tower structures. At the same time, they electrically isolate the high-voltage conductor from the metallic body of the supporting towers. In high-voltage overhead transmission lines, engineers typically install insulator strings at the tip of the cross arms of towers. … Read more
Before we discuss the use of disc insulators in high-voltage transmission lines, let’s understand the need for such insulators. Transmission lines operate at very high voltages such as 66 kV, 132 kV, 220kV, 400 kV, even 765 kV and more. So, the conductors used in these systems are also very heavy. To maintain proper ground clearance, we suspend these … Read more
Engineers prefer to use silicone rubber composite insulators for transmission lines in areas with high pollution levels. In other words, these areas are among the most heavily polluted. These insulators normally have a creepage distance of 31 mm/ kV. The disc insulators used in heavily polluted areas also have a creepage distance of 31 mm/kV. … Read more
Power stations generate electric power. Electrical power transmission lines transmit the generated power to far places. The resistance and reactance of the line cause a voltage drop in the power. The Voltage Regulation of Transmission Line is the change in voltage between the sending and receiving ends. What is Voltage Regulation? We express the Voltage … Read more
A valve-type lightning arrester is an effective type of lightning arrester for high voltage surges. Here, we shall explore how valve-type lightning arresters work and why they were revolutionary in their time. What Is a Valve-Type Lightning Arrester? As stated, a valve-type lightning arrester is a high-voltage surge protection device. It was widely used in … Read more
Skin effect is a phenomenon that occurs in conductors. It mainly occurs while a conductor carries alternating current. Actually, when an alternating current tries to flow through the outer layer of the conductor. The inner portion of the conductor carries much lower current than the outer surface. As a result, the current distribution across the … Read more
The tests are performed as per IS-3181 Type Tests on Earthing Transformer Routine Tests on Earthing Transformer Acceptance Tests on Earthing Transformer
Type Tests on New Transformer Oil or Insulating Oil
Type Tests of SF6 Circuit Breakers as per IS-13118: Routine Tests on SF6 Circuit Breaker as per IS-12729. Acceptance Tests on SF6 Circuit Breaker
Type Tests of Gas Insulated Switchgear Routine Tests on Gas Insulated Switchgear (GIS) The below mentioned tests are performed on complete GIS assembly Below mentioned tests are performed on the individual equivalent like Circuit Breaker: Current Transformer: Potential Transformer: Disconnectors/Isolators: Acceptance Tests of Gas Insulated Switchgear The acceptance tests are the same as factory routine … Read more
The article will focus on the contact design of vacuum interrupters. Before discussing the subject, let us consider why a specific design of contacts is required. The simplest form of contact is the butt-type contact, which has a plain and flat surface. This type of contact is suitable for vacuum circuit breakers with a rated … Read more
Type Tests for a 36kV Class Vacuum Circuit Breaker (VCB) As per IS: 13118, these type tests include: These tests are intended to ensure that the circuit breakers perform reliably, safely, and efficiently under various operating conditions. Routine Tests for a 36kV Vacuum Circuit Breaker (VCB) As per IS: 13118, the routine tests include the … Read more
Before entering the topic of line differential protection, or simply differential protection of a transmission line, we shall first recall our concept of differential protection. Actually, the differential protection used for a transmission line is called line differential protection. We have already heard about the differential protection of transformers, busbars, etc. The same principle is … Read more