What are the types of power transformers, and what are their main components?Power transformers are available in various types to meet the evolving demands of power systems. They can be classified as single-phase or three-phase based on phase configuration; core-type or shell-type according to the relative arrangement of windings and core; and dry-type, air-cooled, forced oil circulation air-cooled, or water-cooled based on cooling methods. In terms of neutral point insulation, transformers are

Surge Arresters: Principles and ApplicationsA surge arrester is a critical device used to protect structures and electrical equipment from lightning strikes. It rapidly diverts and dissipates lightning current, thereby safeguarding equipment and personnel. The following provides a detailed explanation of its working principles.1. Basic Construction of Surge ArrestersA surge arrester typically consists of two main components: a gas discharge tube and a metal oxide varistor (MOV).Gas Discharge Tub

The use of kVA (kilovolt-amperes) instead of kW (kilowatts) to rate transformers stems from the fundamental distinction between real power (kW) and apparent power (kVA) in electrical systems. Transformers transfer electrical energy between circuits via electromagnetic induction, and their kVA rating accounts for both real and reactive power.Real Power (kW): This is the actual power that performs useful work—such as producing mechanical energy, heat, or light—and reflects the transfor

Surge Arresters and Their EvolutionA surge arrester is always connected in parallel with the electrical equipment it protects. It does not interfere with the equipment's normal operation at system voltage. However, when a dangerous overvoltage appears on the equipment, the arrester conducts first, diverting the overvoltage safely into the ground.The earliest and simplest form of surge arrester consisted of two metal rods separated by a gap and connected in parallel across electrical equipment. W

Mechanical Endurance TestingThe mechanical endurance of circuit breakers is tested according to IEC 62271-100, requiring 10,000 operations (M2 class). During testing at an overseas laboratory, the first prototype failed at 6,527 operations due to a trip spring fracture. The lab accepted this isolated failure, attributing it to spring installation issues. A second prototype was tested but similarly failed after over 6,000 operations due to another trip spring breakage. Consequently, the test lab

Most power transformers are oil-immersed, as the use of oil as both a cooling and insulating medium has proven highly effective in the electrical industry. Below are the primary reasons for using oil in power transformers:Cooling: Oil possesses excellent cooling properties. It absorbs heat generated during transformer operation—particularly from the windings and core due to electrical losses—and transfers it away, effectively dissipating thermal energy and preventing overheating.Insu

The efficiency of a power transformer is influenced by a variety of factors, including its design, size, and operating conditions. In general, power transformers are highly efficient, with typical efficiencies exceeding 95%, and often reaching 98% or higher. However, actual efficiency can vary depending on load levels, voltage ratings, and specific design characteristics.Transformer efficiency (η) is defined as the ratio of output power to input power, expressed as a percentage:η = (Outp

The switchgear comprises a fixed cabinet and removable components (i.e., the draw-out unit or "handcart"). The cabinet enclosure and partition plates of each functional unit are constructed from aluminum-zinc-coated steel sheets, precision-formed using CNC machinery and assembled with bolts. This ensures dimensional consistency, high mechanical strength, and excellent resistance to corrosion and oxidation. The overall protection level of the switchgear enclosure is IP4X; when the circuit breaker

Transformer Main ProtectionThe main protection for transformers consists of gas protection and differential protection.Gas ProtectionGas protection is a protective mechanism that responds to internal faults within the transformer tank and to a drop in oil level. When an internal fault occurs in the transformer tank, gases generated from the decomposition of transformer oil and insulation materials due to fault currents and arcing flow from the tank toward the upper part of the oil conservator. T

Main Transformer Backup ProtectionThe purpose of main transformer backup protection is to prevent overcurrent in transformer windings caused by external faults, serve as backup protection for adjacent components (busbars or lines), and, where possible, act as backup for the transformer's primary protection in the event of internal faults. Backup protection is used to isolate faults when primary protection or circuit breakers fail.Main transformer zero-sequence protection is a backup protection f