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In the early days, less 1910 or the early 20th century, most utilities used a bulk oil circuit breaker (BOCB) for high-voltage switching during that time. Earlier air circuit breakers served the purpose of switching high voltage and very high voltage current. But after the 19th century, engineers realized that mineral oil, or specially treated … Read more
Definition of Making Current The rated short circuit making current of a circuit breaker is the maximum peak current that the circuit breaker can close without any damage. It is the maximum peak current that a circuit breaker can make safely. Definition of Breaking Current The rated short circuit breaking current, on the other hand, … 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
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
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
What is LBB Protection? Local Breaker Backup (LBB) Protection is a special protection scheme. This protection isolates a fault from the electrical power system when a circuit breaker fails to do so. When a fault occurs at a particular point in a power system, the primary protection relay associated with that part of the system detects … Read more
An ammeter is connected in the secondary circuit of a current transformer. The ammeter measures the current through the primary of the current transformer. Impact of Fault Current on Secondary Current Now, suppose a fault occurs in the system. Consequently, a large fault current starts flowing through the primary of the current transformer. If the fault current … Read more
The current transformer is a kind of transformer that steps down currents. From the name “current transformer,” we can understand that it deals with current. The available instruments for measuring and protection purposes in the market are of a few amperes range. The ammeters, energy meters, wattmeters, and various protection relays are rated for only … 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