Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

Long-Distance Power Line Distribution: Low Voltage and Large Voltage FluctuationsAccording to the "Technical Guidelines for Distribution Network Planning and Design" (Q/GDW 1738–2012), the supply radius of a 10 kV distribution line must meet the voltage quality requirements at the line’s end. In principle, the supply radius in rural areas should not exceed 15 km. However, in some rural regions, the actual supply radius may extend beyond 50 km due to low load density, small and widely dispersed e

Recently, a ±550 kV DC GIS (Gas-Insulated Switchgear), jointly developed by a Chinese GIS manufacturer and multiple companies, successfully completed a 180-day outdoor long-term energized reliability test at the Xi’an High Voltage Apparatus Research Institute. This marks the first time in the industry that a next-generation ±550 kV DC GIS has passed such a long-term energized evaluation.The ±550 kV DC GIS had already undergone comprehensive performance verification tests at the Xi’an High Voltag

Voltage is an important criterion in power quality testing. The quality of voltage determines whether the power system can operate safely and has a significant impact on the stability of the entire power grid system. Currently, voltage regulators are relatively common electrical equipment in power systems, capable of reasonably and scientifically controlling the entire process of high-voltage tests on electrical equipment, thereby continuously improving the feasibility of such tests.1. Requireme

Power voltage regulators are a major electrical equipment in distribution substations. Since the power supply capacity of most distribution substations is relatively small, the capacity of voltage regulators is generally below 1000 kV·A. Therefore, voltage regulators are transported to the site as complete units, with all accessories assembled at the factory before shipment. Hence, the installation work of power voltage regulators in distribution substations mainly includes transportation, visua

With the implementation of the EU’s new F-Gas Regulation (Regulation (EU) 2024/573), the power equipment industry is entering a countdown toward environmental transformation. The regulation explicitly prohibits, starting in 2026, the use of fluorinated greenhouse gases in medium-voltage switchgear rated at 24 kV and below. This restriction will be extended to equipment up to 52 kV from 2030 onward, accelerating the industry’s shift away from sulfur hexafluoride (SF₆)—a gas with a high global war

1. IntroductionA transformer operates based on the principle of electromagnetic induction. The main components of a transformer are the windings and the core. During operation, the windings serve as the path for electric current, while the core serves as the path for magnetic flux. When electrical energy is input to the primary winding, the alternating current creates an alternating magnetic field in the core (i.e., electrical energy is converted into magnetic field energy). Due to magnetic link

Cooling and Insulation of Dry-Type TransformersA dry-type transformer is a special type of power transformer characterized by the fact that its core and windings are not immersed in insulating oil.This raises a question: oil-immersed transformers rely on insulating oil for both cooling and insulation, so how do dry-type transformers achieve cooling and insulation without oil?First, let’s discuss cooling .Dry-type transformerstypically use two cooling methods: Natural air cooling (AN): When opera

Dry-type transformers refer to power transformers in which the core and windings are not immersed in oil. Instead, the coils and core are cast together (typically with epoxy resin) and cooled by either natural air convection or forced-air cooling. As a relatively newer type of power distribution equipment, dry-type transformers have been widely used in power transmission and distribution systems in factory workshops, high-rise buildings, commercial centers, airports, ports, subways, and offshore

1. Fundamentals of Transformer Testing1.1 OverviewTransformers are among the most critical pieces of equipment for electric power transmission. Their quality and reliability directly affect the safe and dependable delivery of electricity. Damage to generator transformersor key substation transformers can disrupt power transmission, and repairing or transporting such large units often takes several months.During this downtime, power supply is compromised, adversely impacting industrial and agricu

1. Function of Transformer Temperature ControllersToday, power transformers are primarily categorized into two types: oil-immersed and dry-type transformers. Dry-type transformers are widely used in power plants, substations, airports, railways, intelligent buildings, and smart residential communities due to their numerous advantages—such as inherent safety, flame resistance, zero pollution, maintenance-free operation, low losses, minimal partial discharge, and long service life.A key advantage