What are the characteristics of the three commonly used winding configurations in transformers?

a. Y-shaped winding characteristics: The Y-shaped winding has a winding current equal to the line current, with a larger wire cross-section, providing excellent mechanical strength. The winding voltage is equal to 1/√3 times the line voltage, resulting in fewer turns and insulation requirements. The filling factor of the conductor is large, enabling graded insulation. Due to the high filling factor, the inter-turn capacitance is higher, resulting in a uniform distribution of impulse voltage. Additionally, the neutral point can be grounded and used to achieve a four-wire system. The main drawback of this configuration is the absence of a circulating loop for the third harmonic current.

b. D-shaped winding characteristics: The D-shaped winding has characteristics opposite to those of the Y-shaped winding.

c. Z-shaped winding characteristics: The Z-shaped winding shares the advantages of the Y-shaped winding but has 15.5% more turns. Although the Z-shaped winding lacks a circulating loop for the third harmonic, even in the presence of third harmonic flux in the core, the voltages of the third harmonic in the two half-windings are equal in magnitude and opposite in direction. Therefore, there are no third harmonic voltages across the line terminals to the neutral point.

The advantages of the Z-shaped winding include equal and opposite magnetic potentials in the two half-windings when subjected to impulse currents. Consequently, when one side of the winding experiences impulse overvoltage, the other side does not induce overvoltage on itself. However, due to a 30° phase shift between the voltage vectors of the two half-windings, the effective material usage for the winding increases by 15.5%, resulting in larger iron cores and increased costs. Therefore, Z-shaped windings are typically used only on the low-voltage side.

LuShan, est. 1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 49 years. Leading products are single-phase transformer, three-phase transformers, DC inductors, AC reactors, filtering reactor, expoxy resin high-voltage transformer and intermediate, high-frequency products. Our transformers and reactors are widely used in 10 application areas: rapid transit, construction machinery, renewable energy, intelligent manufacturing, medical equipment, coal mine explosion prevention , excitation system, vacuum sintering, central air conditioning.

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