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Surya Normally, most of the utilities use double star ungrounded neutral capacitor banks. They connect series and parallel capacitor units to form that double star design. They normally use it in 33KV systems of electrical power substations. Before going to the detail protection scheme of double star ungrounded 3-phase capacitor bank, we may recall the connection … Read more
Formation of Arc in Medium Before discussing the vacuum arc, let us recall the concept of arc formation in a medium like air, gas, or any other similar medium. Arc during closing contacts Let us switch on a circuit breaker online. Closing of this circuit breaker connects a load to a source. During closing, the … Read more
Introduction to M2 Class Circuit Breakers The M2 class of circuit breaker belongs to a special class defined by IEC 62271-100. This means these circuit breakers require minimal maintenance and can operate mechanically for an extended lifespan. If a breaker performs at least 10,000 mechanical operations without any even minor damage, it comes under M2 … Read more
The C2 Duty Cycle Test confirms a circuit breaker capable of capacitive switching operations. Even a few tens or hundreds of amperes of capacitive current may cause unexpectedly high transient recovery voltage. That is not a healthy condition for the insulation of the system. A circuit breaker interrupts capacitive current when it cuts unloaded transmission … Read more
Introduction In modern medium-voltage power systems, vacuum circuit breakers play a dominant role in safe and efficient current interruption. Engineers prefer these breakers for their robustness, low maintenance requirements, and high dielectric recovery strength. A vacuum circuit breaker, also known as VCB, uses the unique properties of a vacuum to quench electrical arcs. Unlike SF6 … Read more
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