What’s the Operation Steps for Transformer Start-Up？

What’s the Operation Steps for Transformer Start-Up？ (1) For transformers using forced oil circulation, the cooling system should be activated before commissioning. In the case of forced oil circulation water-cooled transformers, the oil system must be activated first, followed by the water system. After discontinuing the water cooling system in winter, the water should be completely drained. (2) If circuit breakers are present, they must be used for commissioning. In the absence of circuit breakers, isolating switches within the specified capacity range can be used for commissioning. (3) The energization of the transformer should be carried out from the power supply side equipped with protective devices. (4) In systems with a […]

In an interleaved manner, how is the leakage flux of the winding distributed, and what kind of electromagnetic force is generated? In the case of a winding arranged in an interleaved manner, the distribution of leakage flux is different from the concentric arrangement mentioned earlier. The predominant type of leakage flux generated in this arrangement is radial leakage flux, and the resulting force is primarily axial. Due to the closely matched radial dimensions of the high-voltage and low-voltage windings, the distribution of turns is essentially uniform. Therefore, not only can axial leakage flux be ignored, but also under normal operating conditions, radial leakage flux is relatively small, resulting in a

In concentric arrangement, how is the distribution of leakage flux in the windings and the resulting electromagnetic forces explained? For double-winding concentric arrangement, the leakage flux is generally smaller than in a single concentric arrangement, and it is even further reduced in multi-winding concentric arrangements. Let’s take the example of a double-winding single concentric arrangement to illustrate how the leakage flux is distributed. In a double-winding setup, the current directions are opposite. Assuming the low-voltage winding current flows outward (represented by ⊙) and the high-voltage winding current flows inward (represented by ×), according to the right-hand rule, the leakage flux between them (represented by dashed lines) must go upward. For

What is the main magnetic flux? What is the leakage magnetic flux? When a winding in a transformer is connected to a power source, it generates a magnetic flux in the core. The magnetic flux generated in the core due to the excitation voltage is called the main magnetic flux, and its magnitude depends on the excitation voltage. During rated voltage excitation, the generation of the main magnetic flux should not lead to core saturation, meaning the magnetic flux density should not reach a saturation state. The main magnetic flux is a phasor and is usually expressed in peak values. When a load current flows through a transformer, it generates

What are the different winding arrangements for transformers? The winding arrangement of a transformer refers to the placement positions of each phase and each coil within the winding. When selecting the winding arrangement, factors such as impedance voltage, convenient lead-out, and a rational insulation structure are considered. Currently, there are two main winding arrangements: concentric and interleaved. In a concentric arrangement, for a double-winding transformer, the low-voltage winding is typically placed inside because it requires a smaller insulation distance from the core. The high-voltage winding is then wrapped around the outside to facilitate the installation of tap changers, which are usually positioned on the high-voltage winding. In an interleaved arrangement,

What is the winding direction of a winding? The winding direction of a winding is closely related to the direction of the magnetic field generated by the current in the winding and the direction of the induced electromotive force in the winding when the magnetic field changes. The winding direction can be divided into two types: left-handed and right-handed. Left-handed winding refers to the counterclockwise rotation of the coil when the wire turns from the start to the middle of the winding; right-handed winding refers to the clockwise rotation of the coil when the wire turns in the winding direction. When winding, facing the winding machine, if the wire enters

What is the Voltage Ratio? The voltage ratio indicated on the nameplate of a transformer refers to the voltage ratio of the transformer under no-load conditions. It serves as a parameter used by the manufacturing factory to assess whether the number of turns in the winding meets the specified requirements. The actual voltage ratio during operation is influenced by the type of load (capacitive or inductive), the magnitude of the load current, and the parameters of the transformer itself, such as resistance and inductance. It is essential to emphasize that the voltage ratio is a concept related to the no-load voltage ratio, not the voltage ratio during actual operation. When

What is the rearrangement of parallel conductors? After the passage of current through conductors, in addition to resistive losses, there is also eddy current loss. Regarding resistive losses, whether the winding is made with a single conductor or multiple parallel conductors, as long as the cross-sectional area and length are the same, resistive losses remain consistent. However, eddy current losses are related to the thickness of the conductor and are caused by axial leakage flux. When the thickness doubles, the eddy current losses increase fourfold. Therefore, to reduce the thickness of the conductor, it is necessary to use multiple parallel conductors when the current is high. In multiple parallel conductors,

What role does the winding play in a transformer? And how is the winding classified? The winding refers to the constituent part of the transformer circuit, made of copper or aluminum conductors with high electrical conductivity. Its design requires sufficient insulation strength, mechanical strength, and heat resistance. Typically, windings are classified into two types: layer-type (layered) and coil-type (disk-type). Layer-type windings involve winding the turns along the axial direction in a continuous manner. These can further be categorized into double-layer cylindrical (two layers) and multi-layer helical (multiple layers). Coil-type windings involve winding the turns continuously along the radial direction to form a coil (or segment), and then arranging multiple coils

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