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

Transformer Vector Group DefinitionThe transformer vector group denotes the phase difference between the primary and secondary sides of a transformer, while also defining the arrangement of high-voltage and low-voltage windings in three-phase transformers. Vector groups are determined by the connection configurations of three-phase transformers, which can be categorized into four main groups based on the phase difference between corresponding line voltages of the high-voltage and low-voltage sid

Pure Resistive AC CircuitA circuit containing only a pure resistanceR(in ohms) in an AC system is defined as a Pure Resistive AC Circuit, devoid of inductance and capacitance. Alternating current and voltage in such a circuit oscillate bidirectionally, generating a sine wave (sinusoidal waveform). In this configuration, power is dissipated by the resistor, with voltage and current in perfect phase—both reaching their peak values simultaneously. As a passive component, the resistor neither

Pure Capacitor CircuitA circuit comprising only a pure capacitor with capacitanceC(measured in farads) is termed a Pure Capacitor Circuit. Capacitors store electrical energy within an electric field, a characteristic known ascapacitance(alternatively referred to as a "condenser"). Structurally, a capacitor consists of two conductive plates separated by a dielectric medium—common dielectric materials include glass, paper, mica, and oxide layers. In an ideal AC capacitor circuit, the current

In a series circuit, the resonant frequency condition occurs when the inductive reactance equals the capacitive reactance. Changing the supply frequency alters the values of XL = 2πfL and XC = 1/2πfC.As the frequency increases, XL rises whileXC falls. Conversely, a decrease in frequency causesXL to drop andXCto rise.To achieve series resonance, the frequency is tuned to fr(pointP in the curve below), whereXL = XC.At series resonance, when XL = XCWhere frdenotes the resonant frequency in he