Substance of Second - harmonic Restraint in Overcurrent ProtectionThe substance of second - harmonic restraint in overcurrent protection is to use the second - harmonic component to judge whether the current is a fault current or an excitation inrush current. When the percentage of the second - harmonic component to the fundamental - wave component is greater than a certain value, it is judged to be caused by the excitation inrush current, and the overcurrent protection is blocked.Therefore, the

Open - Circuit Fault on the Secondary SideOpen - circuit in the secondary side is a typical fault of low - voltage voltage transformers, showing abnormal voltmeter readings (zero/fluctuation), faulty power meters, buzzing noises, and core overheating. When open - circuited, the secondary voltage spikes (no secondary current to balance the primary EMF), causing core saturation, flux distortion, and potential overheating/damage.Causes include loose terminals, poor contact, or human error. In low

Typical Wiring Diagram of 35kV Line Radial π ConnectionWhen a 35kV line adopts a radial power grid structure, a single - side power supply or a double - side power supply radial type can be used according to the situation of the power supply points, and a loop - out interval is reserved at the end of the line.Typical Wiring Diagram of 35kV Line Radial T - ConnectionFor double - radial lines, it is advisable to select a double - side power supply. When the power supply points do not meet the r

Fault Transfer VoltageIn low - voltage distribution systems, there is a type of personal electric shock accident where the accident occurrence point and the system fault point are not at the same location. This kind of accident occurs because after a ground fault happens elsewhere, the generated fault voltage is conducted to the metal casings of other equipment through the PE wire or PEN wire. When the fault voltage on the metal casing of the equipment is higher than the human - body safe voltag

The safe and economical operation of power transformers is related to the safety, economy, stability, and reliability of the operations of various industries. The limitations of conditions such as the investment economic indicators for its selection, the economic benefits of maintenance and operation, and the adaptability in the new environment (access of distributed power sources, configuration of energy storage, etc.) make it impossible to include comprehensive factors in other aspects.The cap

1 IntroductionLow - voltage current transformers for metering, with a through - core type epoxy resin structure, are widely used in distribution transformer areas and for small - to - medium - sized industrial and commercial electricity consumption. As a range expander for electric energy metering, their performance directly relates to electricity consumption safety and the accuracy of users' trade calculations. Studying long - term immersion's impact on these transformers is practically signifi