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How to Reduce Transformer Core Losses? Transformer core losses primarily include eddy current losses and hysteresis losses. Here is an elaboration on methods to decrease core losses: (1) Optimize core material: To minimize losses, selecting core materials with low losses and high saturation magnetic induction is crucial. Silicon steel is currently one of the most widely used materials for transformer cores, and its silicon content effectively reduces eddy current losses. (2) Employ laminating techniques: Transforming silicon steel into laminated sheets can effectively slow down the formation and propagation of eddy currents, thereby reducing loss levels. This laminating technique contributes to enhancing the performance of the core and reducing energy losses.

What Causes Winding Breakage? There are several reasons that can lead to winding breakage in transformers: (1) Unstable Line Connections: When the winding connections in a transformer are problematic, such as poor welding, inadequate contact, or loosening, it may result in concentrated currents or localized overheating at the connection points. Prolonged overheating can accelerate the aging of internal insulation materials, ultimately causing the winding to break. (2) Various Overvoltages: Overvoltage occurs when the voltage surpasses the normal operating range of the equipment. Elevated voltages can increase electric field intensity, damaging the insulation materials of the winding and potentially causing partial or complete winding breakage. Various forms of overvoltage induce overcurrent

What Causes Overheating of Transformer Core? The overheating of a transformer core can be attributed to several factors: (1) Overload: When a transformer operates under excessive load, the current passing through the core increases, generating additional Joule heating. This can result in an elevated temperature of the core, surpassing the design temperature. (2) Iron Loss: The iron loss of the core is related to the magnetic flux density and frequency during transformer operation. If the operating point deviates from the design point, causing an increase in iron loss, it can lead to overheating of the core. (3) Harmonics: During transformer operation, harmonics in the system can induce overheating of the

How is the understanding of withstand voltage and test voltage? In practical operation, transformers and choke coils are exposed to transient overvoltages due to various reasons. Content 1. Illustrate For instance, when a transformer’s power supply is closed, it may generate a transient overvoltage twice the normal operating voltage. Similarly, when the power supply is disconnected, it can produce a transient overvoltage 8 to 10 times the normal operating voltage. Sudden open or short circuits in the load can result in extremely high transient overvoltages, and lightning can induce transient overvoltages of up to 3000 volts. The connection and disconnection of thousands of electrical devices on the same power grid

Why does excitation inrush current occur when a transformer is energized with no load? When a transformer is energized with no load, the excitation current immediately undergoes a transient phase, and its peak value may exceed several times the rated load current. Compared to the normal excitation current, the steady-state no-load current of the transformer is several tens of times larger. This transient current is referred to as excitation inrush current. Excessive inrush current can lead to relay misoperation, preventing the smooth energization of the transformer into the circuit. The magnitude of the inrush current depends on the phase of the line voltage at the moment of transformer energization and

What are the inspection tasks for dry-type transformers? Check for abnormal sounds and vibrations. Look for signs of local overheating, such as insulation surface tracking and discoloration caused by harmful gas corrosion and carbonization. Verify if the transformer’s air-cooling system is operating correctly. Ensure that there is no overheating at high and low voltage connections and no leakage or tracking at cable heads. Monitor the temperature rise of windings, ensuring it does not exceed specified limits based on the insulation material grade used in the transformer. Inspect support insulators for cracks or signs of discharge. Check for any loose winding clamps. Ensure indoor ventilation and core air ducts are free

Why is it necessary to ground the transformer core? And why is it not advisable to use a multi-point grounding approach? The core and its metal components generate different potentials due to their positions in the electric field. When the potential difference between two points reaches a level sufficient to break down the insulation between them, intermittent spark discharges occur. This discharge is intermittent, with the potential between the two points becoming equal after each discharge, causing the discharge to cease. Once a potential difference is reestablished, the discharge occurs again. This intermittent discharge can lead to the decomposition of transformer oil and potential damage to solid insulation, resulting in

How to analyze and dissectthree-phasetransformers? A transformer is a device that transforms AC voltage, current, and impedance. When an AC current flows through the primary coil, an alternating magnetic flux is generated in the core (or magnetic core), inducing voltage (or current) in the secondary coil. With the continuous development of the transformer industry, more and more industries and enterprises are using transformers, and more and more enterprises are entering the transformer industry. Transformers are composed of cores (or magnetic cores) and coils, with two or more windings. The winding that is connected to the power source is called the primary winding, and the remaining windings are called secondary windings.

What protective devices does a three-phase transformer have? Microcomputer Protection Device: The microcomputer protection device for three-phase transformers consists of highly integrated components, chip-on-bus single-chip micro-controllers, high-precision current-voltage transformers, high-insulation-strength output intermediate relays, high-reliability switch power modules, etc. The microcomputer protection device is mainly used for power plants, substations, distribution stations with voltage levels of 110KV and below, and can also be used for the protection and measurement and control of voltage and current systems between some voltage levels between 70V and 220V. Differential Protection Device: The differential protection device for three-phase transformers is mainly used to protect transformer equipment. The differential protection device for transformers should have differential quick-break

How to choose the cooling method for oil-immersed and dry-type forced air-cooled transformers? Oil-immersed forced air-cooled transformers offer two selectable cooling methods: oil-immersed forced air cooling (ONAF) and oil-immersed self-cooling (ONAN). Generally, ONAF cooling is chosen when the transformer operates at 100% rated capacity, while ONAN cooling can be selected when operating at 67% (or other percentages specified by the manufacturer) of the rated capacity. This selection is based on the principle of keeping the winding average temperature rise and the top oil temperature rise within the allowable limits. Without forced air cooling, the heat dissipation efficiency is lower, resulting in a corresponding reduction in output capacity. On the other