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

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

The Short Circuit Ratio (SCR) of a Synchronous MachineThe Short Circuit Ratio (SCR) of a synchronous machine is defined as the ratio of the field current needed to generate rated voltage under open-circuit conditions to the field current required to sustain rated armature current during a short-circuit condition. For a three-phase synchronous machine, the SCR can be derived from its Open-Circuit Characteristic (O.C.C) at rated speed and Short-Circuit Characteristic (S.C.C), as illustrated in the

1. IntroductionIn Vietnam's coastal regions, 20kV reclosers play a critical role in maintaining power supply reliability amid harsh environmental conditions. These devices, compliant with IEC 62271-111 and Vietnam's national standard TCVN, are frequently exposed to salt fog, high humidity, and typhoons, necessitating robust fault management strategies. This article explores typical malfunctions of IP67-rated reclosers in Vietnam and proposes integrated solutions to enhance grid resilience.2. Env

1. IntroductionIn the modern power grid infrastructure, high - voltage reclosers play a pivotal role in enhancing the reliability and efficiency of power supply. This is particularly crucial in regions like Indonesia, which has a vast and complex power distribution network spanning numerous islands, and Vietnam, with its developing coastal power systems. The 20kV voltage level, falling within the medium - high - voltage range, is widely adopted in urban grids, industrial power supply, and certai

Per-Unit System in Electrical Machine AnalysisFor the analysis of electrical machines or their systems, diverse parameter values are often required. The per-unit (pu) system provides standardized representations for voltage, current, power, impedance, and admittance, streamlining calculations by normalizing all values to a common base. This system is particularly advantageous in circuits with fluctuating voltages, where it simplifies cross-referencing and analysis.DefinitionThe per-unit value of

The equivalent circuit diagram of any device can be extremely useful for predicting how the device will behave under different operating conditions. It is essentially a circuit - based depiction of the equations that describe the device's performance.The simplified equivalent circuit of a transformer is constructed by representing all of the transformer's parameters on either the secondary side or the primary side. The equivalent circuit diagram of the transformer is presented below:Let the equi

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

1. IntroductionIn the ever - evolving industrial sector of Vietnam, maintaining a reliable and efficient power supply is of utmost importance. One crucial component in achieving this is the auto recloser, specifically the 630A variant. An auto recloser, or automatic circuit recloser, is a precision automatic switchgear device equipped with smart sensors and electronics. It plays a pivotal role in protecting power lines, grid systems, and electrical equipment in industrial settings.2. Functioning

Transformer Operation Under Load ConditionsWhen a transformer is under load, its secondary winding connects to a load, which can be resistive, inductive, or capacitive. A current I2 flows through the secondary winding, with its magnitude determined by the terminal voltageV2and load impedance. The phase angle between the secondary current and voltage depends on the load characteristics.Explanation of Transformer Load OperationThe operational behavior of a transformer under load is detailed as fol