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

Due to the long service life and severe aging of the equipment, the switches in the 6kV working section of Unit 6 of a certain power plant have potential safety hazards such as deformed locating pins, abnormal closing positions of the earthing switches, and malfunctions of the protection devices. These hazards have threatened the stable operation of the unit, making the transformation extremely urgent. Meanwhile, considering the recent cases of electric shock casualties involving medium-voltage

I. Overvoltage PreventionVacuum circuit breakers excel in interrupting performance, but high overvoltage may occur across inductors during the switching of inductive loads due to abrupt changes in loop current, which requires special attention. When switching small-capacity motors, starting currents are large, so measures like step-down starting should be adopted to limit the current.Transformers with different structures show distinct characteristics: oil-immersed transformers have high impulse

In the first half of 2007, as project participants from the Electromechanical Equipment Company of Huaibei Mining Group, we carried out a technical transformation of the 10kV substation in the East Factory Area. Our primary task was to replace the original 10kV disconnector - oil - immersed circuit breaker units with ZN20 indoor high - voltage vacuum circuit breakers.Previously, the SN10 - 10 oil - immersed circuit breakers had been in operation for an extended period, leading to severe oil leak

I. Equipment Dilemmas in Freezing WintersThe 35kV switch room of the 110kV substation in Luliang Oilfield, commissioned in 2002, has always been a key area for my maintenance team. The original ZN23-40.5/1600 vacuum circuit breakers, equipped with spring operating mechanisms, posed recurring challenges during subzero winters. With over 200 components and a 12-stage mechanical linkage, the spring mechanisms suffered severe wear on sliding friction surfaces. In temperatures as low as -40°C

1. Introduction to Overhead Lines and Reclosers in VietnamVietnam's power distribution landscape is dominated by overhead lines, especially at the 20kV voltage level, which serves both urban centers and rural regions. As of 2024, approximately 65% of Vietnam's 20kV distribution network relies on overhead infrastructure, making it susceptible to environmental factors like lightning, typhoons, and vegetation interference. In this context, reclosers have emerged as critical components to maintain g

1. IntroductionIn power distribution infrastructure, reclosers play a pivotal role in ensuring reliable electricity supply—particularly in countries like Vietnam, where the demand for stable power has grown exponentially with economic development. As of 2024, Vietnam's power grid has formed a complex network, with a significant portion operating at the 20kV voltage level. In this context, reclosers serve as critical components to maintain grid integrity and enhance service quality.2. F

Coordination of Reclosers and Sectionalizers in Distribution NetworksAutomatic reclosers and automatic sectionalizers (reclosers and sectionalizers for short) are relatively complete and highly reliable automated devices. They can not only reliably and promptly eliminate transient faults but also minimize the power outage range caused by permanent faults. Since reclosers and sectionalizers are used in distribution networks, they can selectively and effectively eliminate transient faults to preve

AC High - Voltage Automatic Recloser (Recloser for Short in This Article)The AC high - voltage automatic recloser (referred to as the recloser for short in this article) is a high - voltage switchgear with self - control (it has the functions of fault current detection, operation sequence control and execution by itself, without the need for additional relay protection and operation devices) and protection functions. It can automatically detect the current and voltage passing through the main ci

According to statistics, the vast majority of overhead line faults are "transient", with permanent faults generally accounting for less than 10%. Currently, for 10kV distribution network lines, the combined use of automatic reclosers and sectionalizers can quickly restore power supply after a transient fault and isolate the faulty line section in case of a permanent fault. It is necessary to monitor the operating status of the automatic reclosing controller to enhance its operational reliability

1. Selection of Reclosers and SectionalizersThe selection of reclosers and sectionalizers is crucial for achieving distribution network automation. Sectionalizers cooperate with the upstream circuit breakers on the power supply side. They automatically trip when three conditions are simultaneously met: the fault current exceeds its set - value, the line undervoltage current is less than 300 mA, and the set number of counts is reached. Reclosers are applied in indoor substations or on outdoor pol